Biomass Expansion Factors for Scots pine (Pinus sylvestris), comparison between Catalonia and Finland

Aleksi Lehtonen, Jordi Vayreda 


During this decade countries will report change of carbon stocks in forests according Kyoto protocol. In order to be able to provide this information there is urgent need to improve precision of biomass estimation methods. Most of the uncertainty of carbon accounting of forests lies in biomass and wood density estimations (Laitat et al., 2000). Which results more emphasis for developing more accurate methods that take advantage of available forest inventory data (Fang et al., 1998) and (Fang and Wang, 2001). One tempting approach is to use available biomass expansion factors (BEFs) for other areas as well. This means that biomass expansion information would be extrapolated for areas that don't have information for developing BEFs available.













Impacts of intensive forestry on early rotation trends in site carbon pools in the southeastern US

Raija Laiho

Department of Forest Ecology, University of Helsinki, P.O. Box 27, FIN-00014, Helsinki, Finland

Felipe Sanchez

Forestry Sciences Laboratory, USDA Forest Service, Southern Research Station, P.O. Box 12254, Research Triangle Park, NC 27709, USA

Allan Tiarks

USDA Forest Service, Southern Research Station, Alexandria Forestry Center, Pineville, LA 71360, USA

Phillip M. Dougherty

Mead Westvaco Co., P.O. Box 1950, Summerville, SC 29484, USA

Carl C. Trettin

USDA Forest Service, Southern Research Station, Center for Forested Wetlands Research, Charleston, SC 29414, USA


The effects of different silvicultural practices on site, especially soil, carbon (C) pools are still poorly known. We studied changes in site C pools during the first 5 years following harvesting and conversion of two extensively managed pine-hardwood stands to intensively managed loblolly pine plantations. One study site was located on the lower Atlantic Coastal Plain in North Carolina (NC) and another on the Gulf Coastal Plain in Louisiana (La). Four different harvesting-disturbance regimes were applied: stem only harvest (SO), whole tree harvest (WT), whole tree harvest with forest floor removal (WTFF), and full amelioration, i.e. whole tree harvest, disking, bedding and fertilization (FA; only in NC). Each harvesting-disturbance regime plot was split and one-half received annual herbicide treatments while the other half received no herbicide treatments.  In NC, soil C decreased slightly with WT, and increased with FA, otherwise no significant changes were detected. In La, there was a consistent decrease in soil C content from the pre-harvest value in all cases where herbicides were applied. All treatments caused a reduction in the forest floor C pool in NC. In La, the most intensive treatments also resulted in a decrease in the forest floor C, but to a smaller extent. In contrast, there was no net change in forest floor C with the SO and WT treatments, even though significant amounts of logging slash were added to the forest floor at harvest in the SO plots and not in the WT. Herbicide treatment clearly decreased the C pool of hardwoods and understory, and more than doubled that of planted pines. Carbon accumulation in the planted pines was similar for trees growing in the SO, WT, and WTFF treatments on both the LA and NC sites. The full amelioration treatment (only applied at the NC site) led to a significant increase in C sequestration by the planted pine component. Due to a large amount of voluntary pines, total 5-year pine C pool was highest on the non-herbicided intensive management plots on the NC site, however. The differing response patterns of soil and forest floor C pools between the two sites may be due to their differing drainage-summer rainfall regimes. Our results suggest that while poor drainage-wet summer conditions may be impeding carbon loss from the soil component it may be accelerating the rate of decomposition of the forest floor and slash on the soil surface. Laiho and Sanchez et al. 2003. For. Ecol.  Manage.  174: 177-189.

Author Keywords

Biomass; Carbon; Harvesting; Herbicides; Loblolly pine; Pinus taeda; Soil
















The early impact of adjacent clearcutting and forest fire on riparian zone vegetation in northwestern Ontario

Eric G. Lamb, Azim U. Mallik

Department of Biology, Lakehead University, Thunder Bay, Ont., Canada, P7B 5E1

Robert W. Mackereth
Centre for Northern Forest Ecosystem Research, Ontario Ministry of Natural Resources, Thunder Bay, Ont., Canada, P7B 5E1


The distribution and abundance of vascular plant species in riparian communities was compared between three levels of disturbance in the adjacent upland vegetation. Comparisons were made between riparian zone sites that were undisturbed, sites where clearcuts were separated from the riparian zone by a buffer of upland forest, and sites where a forest fire had burned to the riparian zone-upland ecotone. No significant differences in the overall abundance and distribution of species in the riparian vegetation were found between the three disturbance classes, though a small number of species appeared to increase in abundance at burn sites. These results demonstrate that disturbances in the upland forest do not seriously impact the riparian zone plant community, likely because the riparian species are adapted to a high-light environment and flooding disturbance. The environmental factors that change in the riparian zone following removal of the adjacent forest canopy, including light levels, temperature, and wind penetration, do not appear to have a significant influence on the riparian zone vegetation. These results suggest that aspects of the current riparian management guidelines in northwestern Ontario may need to be re-evaluated. Lanb and Mallik et al. 2003. For. Ecol. Manage. 177: 529-538.


Author Keywords

Riparian management; Vegetation response; Buffer zone
















A method for quantifying vertical forest structure

Penelope A. Latham, Hans R. Zuuring, Dean W. Coble
School of Forestry, University of Montana, Missoula, MT 59812, USA


Vertical forest structure is an attribute of forests that is of interest to many disciplines and is consistently discussed in the context of ecosystem management. The vertical stratification of tree crowns is a forest attribute that influences both tree growth and understory community structure. Therefore, it should be considered when making management decisions that affect the structure of stands. However, current methods of quantifying vertical structure are either arbitrarily-defined and do not represent natural stratification patterns of stands or forests, or are too time consuming for landscape analyses. The program, TSTRAT, was developed to place trees into vertical strata in a structural classification of forest vegetation developed for the Inland Northwest (USA). The primary classification criteria were cover types and classes of stand development described by structural criteria. The TSTRAT algorithm defines strata on the basis of an assumption related to a competition cut-off point among tree crowns in a given area. The predicted strata assignments of trees closely approximated vertical strata that were visually identified, in addition to those identified through cluster analysis. TSTRAT assigns each tree to a stratum, produces various descriptive statistics by vertical stratum, and quantifies overstory tree species diversity and inequality of tree heights. Because TSTRAT simulates the natural vertical arrangement of tree crowns, it is potentially useful in identifying strata that are biologically-related to processes that determine natural vertical stratification patterns. Latham and Zurring et al. 1998. For. Ecol. Manage. 104: 157-170.


Author Keywords

Vertical stratification; Forest structure; Ecosystem management; Competition; Overstory diversity; Size inequality; Gini coefficient; Shannon–Wiener diversity index













Precision of Density Estimates from Fixed-Radius Plots Compared to N-Tree Distance Sampling


Veronica C. Lessard

USDA Natural Resources Conservation Service, Natural Resources Inventory and Analysis Institute, co-located at

USDA Forest Service North Central Research Station, St. Paul, MN 55108

Thomas D. Drummer

Department of Mathematical Sciences, Michigan Technological University, Houghton, MI 49931

David D. Reed

School of Forestry and Wood Products, Michigan Technological University, Houghton, MI 49931



We computed and compared the statistical properties of the estimators for the number of trees/ha (density) for fixed-radius plot and n-tree distance sampling. In forests with random spatial patterns, n-tree distance sampling density estimators are at least as precise as those of plot sampling if the fixed-radius plot size is less than the ratio of ( n – 2) and the expected density, where n is the number of trees included at an n-tree location. A similar result holds for the clustered forest, where the ratio is multiplied by a factor involving a constant of heterogeneity. If the expected number of trees per plot and the plot sizes are the same for both the random and clustered spatial patterns, the variance of the plot sampling density estimator for the clustered pattern will always be greater than for that of the random spatial pattern. Lessard and Drummer et al. 2002. For. Sci. 48: 1–6.


Key Words

Density-adapted sampling, spatial pattern















A Finite Mixture Model for Characterizing the Diameter Distributions of Mixed-Species Forest Stands


Chuangmin Liu, Lianjun Zhang, Craig J. Davis

Faculty of Forestry, State University of New York, College of Environmental Science and Forestry, One Forestry Drive, Syracuse, NY 13210.

Dale S. Solomon, Jeffrey H. Gove

USDA Forest Service Northeastern Research Station, Durham, NH 03824




A finite mixture model is used to describe the diameter distributions of mixed-species forest stands. A three-parameter Weibull function is assumed as the component probability density function in the finite mixture model. Four example plots, each with two species, are selected to demonstrate model fitting and comparison. It appears that the finite mixture model is flexible enough to fit irregular, multimodal, or highly skewed diameter distributions. Compared with traditional methods in which a single Weibull function is fit to either the whole plot or each species component separately, the finite mixture model produces much smaller root mean square error and bias, and fits the entire distribution of the plots with extreme peaks, bimodality, or heavy-tails well. In some cases, a single Weibull function fitted to individual species separately may produce more accurate estimations for the component distributions of the two species than the finite mixture model. The summation of the two independent species results, however, may not produce a better prediction for the entire plot. This study shows that the finite mixture model is a promising alternative method for modeling the diameter distribution of multispecies mixed forest stands. Liu and Zhang et al. 2002. For. Sci. 48: 653–661.















An Individual-Tree Growth and Yield Prediction System for Even-Aged Natural Shortleaf Pine Forests


Thomas B. Lynch

Department of Forestry, Oklahoma State University, Agricultural Hall Room 008C, Stillwater, OK 74078

Kenneth L. Hitch, Michael M. Huehschmann

Department of Forestry, Oklahoma State University, Agricultural Hall Room 008C, Stillwater, OK 74078

Paul A. Murphy

Southern Research Station, University of Arkansas at Monticello, P.O. Box 3.516, UAM Monticello, AR 716.56-3516


The development of a system of equations that model the growth and development of even-aged natural shortleaf (Pinus echinata Mill.) pine forests is described. The growth prediction system is a distance-independent individual-tree simulator containing equations that predict basal-area growth, survival, total and merchantable heights, and total and merchantable volumes for shortleaf pine trees. These equations were combined into a computer simulation program that predicts future states of shortleaf pine stands from initial stand descriptions. Comparisons of observed and predicted ending stand conditions in shortleaf pine research plots indicate the simulator makes acceptable forecasts of final stand attributes. Lynch and Hitch. et al. 1999. South. J. Appl. For. 23: 203-211.
















Random-Effects Models for Longitudinal Data


Nan M. Laird

Department of Biostatistics, Harvard School of Public Health, 677 Huntington Avenue, Boston, Massachusetts 021 15, U.S.A. and Department of Statistics, Harvard University, Science Center 603, 1 Oxford Street, Cambridge, Massachusetts 02138, U.S.A.

James H. Ware

Department of Biostatistics, Harvard School of Public Health, 677 Huntington Avenue, Boston, Massachusetts 021 15, U.S.A.



Models for the analysis of longitudinal data must recognize the relationship between serial observations on the same unit. Multivariate models with general covariance structure are often difficult to apply to highly unbalanced data, whereas two-stage random-effects models can be used easily. In two-stage models, the probability distributions for the response vectors of different individuals belong to a single family, but some random-effects parameters vary across individuals, with a distribution specified at the second stage. A general family of models is discussed, which includes both growth models and repeated-measures models as special cases. A unified approach to fitting these models, based on a combination of empirical Bayes and maximum likelihood estimation of model parameters and using the EM algorithm, is discussed. Two examples are taken from a current epidemiological study of the health effects of air pollution. Laird and Ware 1982. Biometrics 38: 963-974.















A generalised model of forest productivity using simplified concepts of radiation-use efficiency, carbon balance and partitioning


J. J. Landsberg

CSIRO Centre for Environmental Mechanics, P.O. Box 821 Canberra, A.C.T. 2614 Australia
and R. H. Waring
Oregon State University, College of Forestry Corvallis, OR 7331 USA


This paper describes a stand growth model, based on physiological processes, which incorporates a number of steps and procedures that have allowed considerable simplification relative to extant process-based models. The model, called 3-PG (use of Physiological Principles in Predicting Growth), calculates total carbon fixed (gross primary production; PG) from utilizable, absorbed photosynthetically active radiation ( small phi, Greekp.a.u.), obtained by correcting the photosynthetically active radiation absorbed by the forest canopy ( small phi, Greekp.a.) for the effects of soil drought, atmospheric vapour pressure deficits and stand age. PG is obtained from small phi, Greekp.a.u. and the canopy quantum efficiency, values of which are becoming available. The ratio of net (PN) to gross primary production is emerging as relatively constant for trees. This eliminates the need to calculate respiration and is used to estimate PN--the net amount of carbon converted to biomass. 3-PG uses a simple relationship to estimate the amount of carbon allocated below ground and a procedure based on allometric ratios--widely available for many species and situations--to determine the allocation of carbon to foliage and stems and constrain tree growth patterns. The effects of nutrition are incorporated through the carbon allocation procedure; the amount of carbon allocated below ground will increase with decreasing soil fertility. Recently acquired knowledge about the physiological factors causing decline in forest growth rates with age is used to model that decline. Changes in stem populations (self-thinning) are derived from a procedure based on the Imagepower law, combined with stem growth rates.

The model requires weather data as input, works on monthly time steps and has been run for periods up to 120 years, producing realistic patterns of stem growth and stem diameter increments. The time course of leaf area index is realistic for a range of soil conditions and atmospheric constraints. 3-PG can be run from remotely-sensed estimates of leaf area index coupled to weather data and basic, readily available information about soils and stand characteristics. It is being tested as a practical tool against forestry data from New South Wales, Tasmania, Victoria and New Zealand. Test results show excellent correspondence between stand growth measurements and simulated stem growth over 30 years. Landsberg and Waring 1997. For. Ecol. Manage. 95: 209-228.

Author Keywords

Forest model; Carbon balance; Partitioning; Physiological processes; Weather















Science and the Management of Boreal Forest Biodiversity


Stig Larsson

Department of Entomology, Swedish University of Agricultural Sciences, P.O. Box 7044, SE-750 07 Uppsala, Sweden

Kjell Danell

Department of Animal Ecology, Swedish University of Agricultural Sciences, SE-901 83 Umea, Sweden



The two most important consequences of modern large-scale forestry for biodiversity are the loss of habitats and the transformation of remaining habitats into homogenous and production intensive systems. In order to counteract these negative effects Fennoscandian forestry has introduced a number of biodiversity-oriented management practices, e.g., creation of artificial snags, green tree retention, prescribed burning, creation of corridors and buffer strips. Most, if not all, of the new silvicultural methods were introduced based only on scanty scientific evidence. In this paper background to the present situation in Fennoscandian boreal forestry is given in order to introduce papers presented at a Swedish: Finnish workshop on ‘‘Science and the Management of Boreal Forest Biodiversity’’ at Olofsfors, Sweden in September 1999. The fact that Fennoscandian forestry has practiced large-scale biodiversity management for more than a decade provides us with a unique opportunity to scientifically evaluate the accuracy of these methods. As we progress in scientific understanding modifications in management practices can be made and their outcomes evaluated both in term of biodiversity and timber production. Larsson and Danell 2001. Scand. J. For. Res. Suppl 3: 5–9.















Modeling the Joint Distribution of Tree Diameters and Heights by Bivariate

Generalized Beta Distribution


Fasheng Li, Lianjun Zhang, Craig J. Davis

Faculty of Forestry, State University of New York, College of Environmental Science and Forestry, One Forestry Drive, Syracuse, NY 13210



A bivariate generalized beta distribution (GBD-2) is fit to the joint frequency distribution of tree diameters and heights of 43 Douglas-fir ( Pseudotsuga menziesii var. glauca [Beissn.] Franco) plots in Idaho. The model fitting and performance are compared with the Johnson’s SBB distribution using goodness-of-fit c2 tests for the marginal distributions of diameters and heights, a bivariate goodness-of-fit test for the joint distribution of the two variables, and model predictions of tree heights and volumes. We found that the GBD-2 is more flexible and successful than the Johnson’s SBB in describing both marginal and joint distributions of tree diameters and heights. On average, the relative bias (%) from the GBD-2 is three times smaller than that from the Johnson’s SBB across the 43 plots when the models are used in tree volume prediction. Li and Zhang et al. 2002. For. Sci. 48(1):47-58.


Key Words

Generalized beta distribution, bivariate generalized beta distribution, Johnson’s SBB distribution, goodness-of-fit test.














Newton-Raphson and EM Algorithms for Linear Mixed-Effects Models for Repeated-Measures Data


Mary J. Lindstrom

Biostatistics Center, University of Wisconsin-Madison, Madison, Wisconsin 53706, U.S.A.

Douglas M. Bates

Department of Statistics, University of Wisconsin-Madison, Madison, Wisconsin 53706, U.S.A.



We develop an efficient and effective implementation of the Newton-Raphson (NR) algorithm for estimating the parameters in mixed-effects models for repeated-measures data. We formulate the derivatives for both maximum likelihood and restricted maximum likelihood estimation and propose improvements to the algorithm discussed by Jennrich and Schluchter (1986) to speed convergence and ensure a positive-definite covariance matrix for the random effects at each iteration. We use matrix decompositions to develop efficient and computationally stable implementations of both the NR algorithm and an EM algorithm (Laird and Ware 1982) for this model. We compare the two methods (EM vs. NR) in terms of computational order and performance on two sample data sets and conclude that in most situations a well-implemented NR algorithm is preferable to the EM algorithm or EM algorithm with Aitken's acceleration. The term repeated measures refers to experimental designs where there are several individuals and several measurements taken on each individual. In the mixed-effects model each individual's vector of responses is modeled as a parametric function, where some of the parameters or "effects" are random variables with a multivariate normal distribution. This model has been successful because it can handle unbalanced data (different designs for different individuals), missing data (observations on all individuals are taken at the same design points, but some individuals have missing data), and jointly dependent random effects. The price for this flexibility is that the parameter estimates may be difficult to compute. We propose some new methods for implementing the EM and NR algorithms and draw conclusions about their performance. We also discuss extensions of the mixed-effects model to incorporate nonindependent conditional error structure and nested-type designs. Lindstrom and Bates 1988. J.  Am.  Stat. Assoc., 83: 1014-1022.















Increasing carbon stocks in the forest soils of western Europe

Jari Liski
European Forest Institute, Torikatu 34, FIN-80100, Joensuu, Finland and Department of Forest Ecology, University of Helsinki, P.O. Box 27, FIN-00014, Helsinki, Finland
Daniel Perruchoud

Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), National Forest Inventory, CH-8903, Birmensdorf, Switzerland
Timo Karjalainen
European Forest Institute, Torikatu 34, FIN-80100, Joensuu, Finland


The soils of western European forests may be accumulating carbon, because tree biomass has been expanding in these forests already for decades, and the more numerous and larger trees can produce more litter. We calculated the carbon budget of soils and trees in the forests of 14 EU countries plus Norway and Switzerland from 1950 to 2040 by integrating forest resource information (inventory data from 1950 to 1990 and a forest resource forecast from 2000 to 2040), biomass allocation and turnover information, and a dynamic soil carbon model.


The carbon stock of the soils increased throughout the studied period. In 1990, the soil carbon sink was 26 Tg per year. This is 32 or 48% compared with our two estimates of the tree carbon sink for that year. Until 2040, the soil carbon sink was estimated to increase to 43 Tg per year. This would already be 61 or 69% compared with the tree carbon sink that year. In 1990, the soils contributed most to the total forest carbon sink in central Europe, where the soil carbon sink was almost as large as the tree carbon sink. The soils were least important in southern Europe, where the soil carbon sink was less than 25% compared with the tree carbon sink. In the future, the contribution of the soils to the total forest carbon sink was estimated to increase everywhere except in southern Europe.


The soil carbon stocks increased mainly because litter fall from living trees increased while the other sources of soil carbon, i.e. the residues of harvests and natural disturbances, varied less. This litter fall was also the largest source of soil carbon accounting for 70–80% of the total. The soil carbon stocks in these forests could thus be most effectively controlled by forest management actions, such as the choices of harvest regimes or tree species, which especially affect the litter production of living trees. According to an uncertainty analysis, we may have overestimated the soil carbon sink by 35% or underestimated it by 50% throughout the studied period. The largest uncertainties were related to calculating the litter production of living trees and decomposition in soil. Liski and Perruchoud 2002. For. Ecol.  Manage. 169: 159-175.


Author Keywords

Carbon flux; Carbon sink; Carbon stock; Forest inventory; Kyoto protocol; Soil carbon; Tree biomass














Growth and Yield in Managed Natural Stands of Loblolly and Shortleaf Pine in the West Gulf Coastal Plain


Burton, J.D.

Alexandria Forestry Center, Southern Forest Experiment Station, Forest Service-USDA, Pineville, Louisiana



Second-growth even-aged loblolly-shortleaf pine stands on good and medium sites were thinned from above or below to a basal area of 70 ft2, 85 ft2, and 100 ft2/acre, to an increasing basal area, or according to the judgment of a committee. Treatments began at age 20 for original plots and at age 25 for supplementary plots (on good sites only), which were thinned to a basal area of 55ft2, 115 ft2, or 130 ft2/acre.Stands were thinned every 5 years. At age 45, most trees in good-site original plots and supplementary plots thinned from below were in the l0-inch d.b.h. class and larger. In the 70-ft2, 85-ftk,and "increasing" treatments, most stems were in the 15-inchclass and larger. On good-site original plots thinned from below, at 45 years standing sawtimber volume for trees (>=)9.6 inches d.b.h. containing (>,=) one 16-ft log to an 8-inchtop was greatest in "increasing" treatment plots and least in 85-ft2and 100-ft2/acre plots. In supplementary plots, standing board-foot volume was greatest in 130-ft2 and least in 55-ft2/acreplots. On medium sites, standing volume was greatest in "judgment" and l00ft and least in 70 ft2/acreplots. Sawtimber m.a.i. was still increasing rapidly at age 45 in all treatments. Cubic-foot m.a.i. was increasing slowly on medium sites but declining in supplementary plots and in all good-site original plots except the 70-ft" and "increasing" treatments. On good sites, p.a.g. in board feet culminated between ages 30 and 35 in the 70-ft2/ and 85.ft2 treatments and between ages 40 and 45 in "increasing" plots. On medium sites, p.a.g. apparently was still increasing at 45 years. On both sites, sawtimber ingrowthwas much less complete at age 45 in thin-from-above stands than in those thinned from below. On good sites, sawtimber yield to age 45 in plots thinned from below was greatest in "increasing" treatment plots and least in l00- ft2/acre stands. In supplementary plots, sawtimber yield was greatest in 55-ft2 and least in 115-ft2/acre treatments. On medium sites, sawtimber yield was greatest in "judgment" and l00ft and least in 70-ft2/acre stands. On good sites, cubic-foot yield to age 45, in peeled stemwoodto a 3-inch d.i.b., trees (>,=) 3.6 inches d.b.h., in plots thinned from elow,was greatest for "increasing" treatment plots and least for 70-ft2 stands. In supplementary plots, cubic-foot yield was greatest for 130-ft2 and least for 55-ft2 /acre plots. On medium sites, cubic-foot yield was greatest for 100.ft2and least for 70-ft2/acre stands. Burton 1980. U.S. Department of Agriculture Forest Service Research Paper SO-159.















Forest site classification and evaluation: a South African perspective

J. H. Louw
 Department of Forestry, Port Elizabeth Technikon, P/B X6531, George 6530, South Africa

M. Scholes
 Department of Animal, Plant and Environmental Sciences, University of Witwatersrand, P/B 3, Wits 2050, South Africa


The current South African forest resource is managed through intensive silviculture of fast-growing exotic species. Increased intensity in managed practices in a forestry environment that is characterized by diversity in growing conditions, will require reliable decision support tools that facilitate informed decision making. This paper highlights the conceptual approach of forest site classification, the development of site evaluation models, and the formulation of management systems and policies. The multi-factor, hierarchical approach to site classification used in South Africa is discussed against an international perspective, and possible future directions are highlighted. A review is provided on the outcome of site-growth studies undertaken in South Africa, and the importance of development towards process-based models is indicated. The highly variable, site-specific response found with fertilizer trials is outlined, and the importance of site-classification systems in formulating nutrient management policies is also highlighted. The status of growth and yield modeling in South Africa is briefly discussed, including the crucial role of site-classification systems in developing site-specific growth models. The development of a policy regarding sustainable forest management is a priority, and the importance of spatial site information in this venture is discussed. The integration of the three different concepts; site classification, site evaluation and management systems, into a common platform for decision making, is proposed. Together with geographic information technology, these integrated components can form the essential elements to a forest management decision support system. Louw and Scholes 2002. For. Ecol. Manage. 171: 153-168.


Author Keywords

Site classification; Site evaluation; Site index prediction modeling; Nutrient management; Growth and yield modeling; Plantation decision support system; Sustainability













A review of the effects of silviculture on timber quality of Sitka spruce

Elspeth MacDonald, Jason Hubert

Forest Research, Northern Research Station, Roslin, Midlothian EH25 9SY, Scotland

This review focuses on timber quality with a particular emphasis on Sitka spruce and sawlog production, although issues pertaining to pulp and panel quality are also dealt with. The review is split into three broad areas. The first covers the factors controlling wood quality that operate within the timber itself and also at the whole-tree scale. These include knots, grain angle, wood density, tracheid length, microfibril angle, juvenile wood and compression wood, tree/log size, growth rate, stem straightness and stem taper. The second section reviews the link between silviculture, site and genetics on these controlling factors and the consequences for wood quality for different end-uses. The silvicultural factors reviewed are rotation length, initial spacing, respacing before canopy closure, thinning after canopy closure, nursing mixtures, pruning, cultivation, weed suppression and fertilizer use. Site factors include site quality, wind, slope, and snow and ice. There is a brief section on the role of genetic improvement on timber quality. Finally, the review provides conclusions and recommends that stands should be identified as being suitable for sawlogs or fibre products and then managed consistently throughout the rotation with a strong focus on the final wood product. For Sitka spruce, the objective of maximizing volume yield appears to be compromising batten performance and buyers should consider premiums for stands where quality has been provided rather than quantity. Long-term forest plans and certification could play an increasing role in providing the assurance that good consistent silvicultural practice had been undertaken throughout the rotation, hence creating the possibility of offering clear premiums for high grade timber.
MacDonald and Hubert 2002. For. 75: 107-138.














Radial growth variation of Norway spruce (Picea abies (L.) Karst.) across latitudinal and altitudinal gradients in central and northern Europe

Harri Mäkinen, Pekka Nöjd

Finnish Forest Research Institute, P.O. Box 18, FIN-01301, Vantaa, Finland

Hans-Peter Kahle

Institute of Forest Growth, University of Freiburg, Bertoldstr 17, D-79085, Freiburg, Germany

Ulrich Neumann

Institute of Forest Growth and Forest Informatics, University of Dresden, Wilsdrufferstr. 18, D-01737, Tharandt, Germany
Björn Tveite

Norwegian Forest Research Institute, Hoegskolevn. 12, N-1432, Ås, Norway

Kari Mielikäinen

Finnish Forest Research Institute, Unioninkatu 40, FIN-00170, Helsinki, Finland
Heinz Röhle

Institute of Forest Growth and Forest Informatics, University of Dresden, Wilsdrufferstr. 18, D-01737, Tharandt, Germany
Heinrich Spiecker
Finnish Forest Research Institute, P.O. Box 18, FIN-01301, Vantaa, Finland


Regional and temporal growth variation of Norway spruce (Picea abies (L.) Karst.) and its dependence on air temperature and precipitation were compared in stands across latitudinal and altitudinal transects in southwestern and eastern Germany, Norway, and Finland. The temporal variation of radial growth was divided into two components: medium- and high-frequency variation, i.e. decadal and year-to-year variation, respectively. The medium-frequency component was rather different between regions, especially the southern and northern ones. However, within each region the medium-frequency growth variation was relatively similar, irrespective of altitudinal and latitudinal differences of the sample sites. A part of the high-frequency variation was common to all four regions, which suggests that some factors synchronising tree growth are common for the entire study area. The high-frequency component of growth was more strongly related to monthly air temperature and precipitation than was the medium-frequency variation. The limiting effect of low temperatures was more significant at northern as well as high-altitude sites, while the importance of precipitation increased in the south and at low altitudes. Mäkinen and Nöjd et al. 2002. For. Ecol. Manage. 171: 243-259.


Author Keywords

Altitude; Climatic response; Dendrochronology; Growth variation; Latitude; Picea abies














Modeling Changes in Wildlife Habitat and Timber Revenues in Response to Forest Management


  John M. Marzluff

College of Forest Resources, University of Washington, Box 352100, Seattle, WA 98195

Joshua J. Millspaugh

Department of Fisheries and Wildlife Sciences, University of Missouri, 302 A-BNR Building, Columbia, MO 65211

Kevin R. Ceder, Chadwick D. Oliver, John Withey, James B. McCarter, C. L. Mason, Jeffrey Comnick

College of Forest Resources, University of Washington, Box 352100, Seattle, WA 98195



Few models evaluate the effects of forest management options on wildlife habitat and incorporate temporal and spatial trends in forest growth. Moreover, existing habitat models do not explicitly consider economic trade-offs or allow for landscape level projections. To address these concerns, we linked standard wildlife habitat suitability models with habitat projections from the Landscape Management System (LMS). LMS integrates spatially explicit forest inventories with forest growth, decay, and silviculture treatment (e.g., planting, thinning, harvesting) models to compare some economic and biological impacts of forest management on wildlife habitats at spatial scales ranging from the individual forest stand to the landscape. We used LMS to quantify pileated woodpecker ( Dryocopus pileatus), Cooper’s hawk (Accipiter cooperi), and southern red-backed vole (Clethrionomys gapperi) habitat qualities across landscapes and to project habitat changes through time. We modeled five forest management scenarios (including no action, intensive management for timber production, moderate management and intensive management to enhance mature forest structure, and mixed management for wildlife and timber) proposed for the 566 ha Satsop Forest in western Washington. The selected wildlife species’ habitats (mixture of mature conifer and deciduous forests) were maximized by simply allowing the forest to grow with no management. However, this cost an estimated $929,539/yr in lost timber revenue. Intensive thinning, replanting, and retention of large trees increased habitat for all focal species and provided $384,558/yr return from timber. Because of potential short-term reductions in habitat that occur during long-term enhancement strategies (e.g., intensive thinning) and limited ability to model understory growth dynamics, monitoring and validation of predictions would be necessary. Marzluff and Millspaugh et al. 2002. For. Sci. 48: 191–202.


Key Words

Economics, forest modeling, habitat suitability, landscape ecology, forest management, wildlife habitat.














Models for Mapping Potential Habitat at Landscape Scales: An Example Using Northern Spotted Owls



William C. McComb

Department of Natural Resources Conservation, University of Massachusetts, Amherst, MA

Michael McGrath

Department of Forest Science, Oregon State University, Corvallis, OR 97331

Thomas A. Spies

USDA Forest Service Pacific Northwest Research Station, 3200 SW Jefferson Way, Corvallis, OR 97331

David Vesely

Pacific Wildlife Research, 1521 NW Harrison Blvd., Corvallis, OR, 97330



We are assessing the potential for current and alternative policies in the Oregon Coast Range to affect habitat capability for a suite of forest resources. We provide an example of a spatially explicit habitat capability model for northern spotted owls (Strix occidentalis caurina) to illustrate the approach we are taking to assess potential changes in habitat capability for vertebrates across the Coast Range. The model was based on vegetation structure at five spatial scales: the potential nest tree, a 0.5 ha potential nest patch, 28 ha around a potential nest patch, 212 ha around a potential nest patch, and a 1,810 ha home range area around a potential nest patch. Sensitivity analyses indicated that the proportion of the 28 ha patch in large trees around a potential nest patch, and the number of potential nest trees per ha in the nest patch, had the greatest influence on habitat capability estimates. The model was verified using georeferenced locations of spotted owl nests from systematically surveyed areas. Logistic regression analysis indicated that habitat capability scores were significantly associated with the probability of a site having a nest. Alternative model structures were tested during verification to test assumptions associated with four variables. The final model allowed development of a map of habitat capability for spotted owl nesting. The model will be linked to a model of forest dynamics to project changes in habitat capability under alternative land management policies. McComb and McGrath et al. 2002. For. Sci. 48(2) : 203–216.


Key Words

Wildlife habitat relationships, forest habitat, forest planning.
















Accuracy of Eastern White Pine Site Index Models Developed in The Southern Appalachian Mountains


W. Henry McNabl

Bent Creek Experimental Forest, 1577 Brevard Road, Asheville, NC 28806



Three older, anamorphic eastern white pine (Pinus sfrobus L.) site index models developed in the southern Appalachian Mountains between 1932 and 1962 were evaluated for accuracy and compared with a newer, polymorphic model developed in 1971. Accuracies of the older models were tested with data used in development of the 1971 model, in which actual site index had been determined by stem analysis. The 1971 model could not be evaluated for accuracy because independent data were unavailable. Evaluation statistics included prediction accuracy, bias, variance, mean square error, and tolerance interval. For one of the older models, prediction accuracy within 5 percent of observed site index was 100 percent, and other statistics compared favorably. Based on the premise that a polymorphic model best describes growth of eastern white pine over a range of site qualities, the site index model developed in 1932 performed surprisingly well. McNabl 2002. Outcalt, Kenneth W., ed. 2002. Proceedings of the eleventh biennial southern silvicultural research conference. Gen. Tech. Rep. SRS-48. Asheville, NC: U.S. Department of Agriculture, Forest Service, Southern Research Station. 622 p.
















Regional estimation of current and future forest biomass

R. A. Mickler

Mantech Environmental Technology, Inc., 920 Main Campus Drive, Venture Center II Suite 300, Raleigh, NC 27606, USA
T. S. Earnhardt

North Carolina State University, 920 Main Campus Drive, Venture Center II Suite 300, Raleigh, NC 27606, USA
J. A. Moore
 USDA Forest Service, 920 Main Campus Drive, Venture Center II Suite 300, Raleigh, NC 27606, USA


The 90,674 wildland fires that burned 2.9 million ha at an estimated suppression cost of $1.6 billion in the United States during the 2000 fire season demonstrated that forest fuel loading has become a hazard to life, property, and ecosystem health as a result of past fire exclusion policies and practices. The fire regime at any given location in these regions is a result of complex interactions between forest biomass, topography, ignitions, and weather. Forest structure and biomass are important aspects in determining current and future fire regimes. Efforts to quantify live and dead forest biomass at the local to regional scale has been hindered by the uncertainty surrounding the measurement and modeling of forest ecosystem processes and fluxes. The interaction of elevated CO2 with climate, soil nutrients, and other forest management factors that affect forest growth and fuel loading will play a major role in determining future forest stand growth and the distribution of species across the southern United States. The use of satellite image analysis has been tested for timely and accurate measurement of spatially explicit land use change and is well suited for use in inventory and monitoring of forest carbon. The incorporation of Landsat Thematic Mapper data coupled with a physiologically based productivity model (PnET), soil water holding capacity, and historic and projected climatic data provides an opportunity to enhance field plot based forest inventory and monitoring methodologies. We use periodic forest inventory data from the USDA Forest Service's Forest Inventory and Analysis (FIA) project to obtain estimates of forest area and type to generate estimates of carbon storage for evergreen, deciduous, and mixed forest classes for use in an assessment of remotely sensed forest cover at the regional scale for the southern United States. The displays of net primary productivity (NPP) generated from the PnET model show areas of high and low forest carbon storage potential and their spatial relationship to other landscape features for the southern United States. At the regional scale, predicted annual NPP in 1992 ranged from 836 to 2181 g/m2/year for evergreen forests and 769–2634 g/m2/year for deciduous forests with a regional mean for all forest land of 1448 g/m2/year. Prediction of annual NPP in 2050 ranged from 913 to 2076 g/m2/year for evergreen forest types to 1214–2376 g/m2/year for deciduous forest types with a regional mean for all forest land of 1659 g/m2/year. The changes in forest productivity from 1992 to 2050 are shown to display potential areas of increased or decreased forest biomass. This methodology addresses the need for spatially quantifying forest carbon in the terrestrial biosphere to assess forest productivity and wildland fire fuels. Mickler and Earnhardt et al. 2002. Environ. Pollut. 116, Supplement 1: S7-S16


Author Keywords

Forest carbon; Productivity modelling; Fuel loading; Net primary production














Comparison of Three Dendrometers in Measuring Diameter at Breast Height


Leigh Ann Moran

Columbus Wood Products, 1165 Kinnear Road, Columbus, OH 43212-1162

Roger A. Williams

School of Natural Resources, 210 Kottman Hall, The Ohio State University, 2021 Coffey Road, Columbus, OH 43210-1085.



Three dendrometers—d-tape, calipers, and Biltmore stick—were used to measure diameter at breast height (dbh), and discrepancies that occurred among these instruments were compared. Three methods of dbh estimation with calipers—the quadratic, arithmetic, and geometric mean of the major and minor axis diameter—were compared. Trees were grouped into four broad dbh classes of 1–5, 6–10, 11–15, and 16–20 in. and three species—northern red oak, sugar maple, and white ash—to determine the effect of tree size and species on discrepancies. The d-tape consistently recorded a larger dbh than the three caliper methods, but was not statistically different nor practically important. The differences in recorded dbh between the d-tape and calipers increased with tree size and were similar among northern red oak and sugar maple trees, but dbh differences in white ash trees were significantly less than in the other two species. The Biltmore stick’s accuracy in classifying trees into the same dbh class as determined by the d-tape decreased as tree size increased. When examined by species, the Biltmore stick was less accurate in this regard with northern red oak and most accurate with sugar maple. Because the geometric principle of the d-tape assumes a tree to have a circular shape, its diameter estimation and subsequent basal area will usually be greater than the true diameter and area. The use of calipers reduces this bias, but the differences are not statistically significant. Moran and Williams 2002. North. J. Appl. For. 19(1):28–33.


Key Words

Calipers, d-tape, Biltmore stick, dbh measurement















Growth and carbon stocks of a spruce forest chronosequence in central Europe

M. Mund

Max-Planck-Institute for Biogeochemistry, P.O. Box 100164, D-07701, Jena, Germany
E. Kummetz

Department for Plant Ecology, University of Bayreuth, D-95440, Bayreuth, Germany
M. Hein

Max-Planck-Institute for Biogeochemistry, P.O. Box 100164, D-07701, Jena, Germany
G. A. Bauer

Harvard University, Department of Organismic and Evolutionary Biology, The Biolabs Rm 394,16 Divinity Ave., Cambridge, MA 02138, USA
E. -D. Schulze

Max-Planck-Institute for Biogeochemistry, P.O. Box 100164, D-07701, Jena, Germany


Human induced changes in global environmental conditions are expected to influence or, as it is hypothesised in this study, have already influenced the biomass and growth of forest ecosystems. In this study, we reconstruct the history of tree growth and quantify the standing biomass along a chronosequence of six Norway spruce stands (Picea abies [L.] Karst; 16–142 years old) on acid soils in a mountainous region with high nitrogen deposition. The inventories of the study sites, as well as the historical stem growth of the sample trees were compared with common yield tables, representing growing conditions before 1960, to find out if and when significant changes in growth of trees had occurred. The growth at tree level (0.003–0.030 m3 yr-1) was about 150–350% higher than predicted by the yield tables, independent of tree age. Because of low stand densities due to early thinning, the increase of stem growth at stand level (90% higher than yield table predictions) and the stand volume (35% higher than yield table predictions) were not as high as the increase of growth at tree level. Total biomass at stand level (including stems, branches, twigs, needles and roots) ranged between 35 and 180 t C ha-1. Net primary productivity varied between 6 and 13 t C ha-1 yr-1. Intensive tree thinning activities probably stimulated growth of remaining trees, but the observed growth rates were beyond what would be expected from these activities exclusively. Thus it is assumed that the fertilization effects of increased nitrogen deposition and CO2 concentration, and improved climatic conditions due to ongoing climate change, have contributed to the observed changes in stem growth and that the thinning activities were synergetic with changing environmental conditions. The implications for carbon sinks as accountable under the Kyoto Protocol are probably small, because changes in environmental conditions are not accountable under the Kyoto Protocol and most of the observed changes in growth took place before 1990, the baseline for the Kyoto Protocol. Additionally, it is assumed that impacts on the carbon balance of forest stands due to changes in the thinning regime after 1990, which would be accountable according to article 3.4 of the Kyoto Protocol, are very small without any synergetic changes in environmental conditions. Mund and Kummetz et al. 2002. For. Ecol. Manage. 171: 275-296


Author Keywords

Carbon stocks; Forest growth; Picea abies; Net primary productivity; Chronosequence; Yield tables; Forest management; Nitrogen deposition; Carbon dioxide fertilisation; Magnesium nutrition; Kyoto protocol.














Scale and Unit Specification Influences in Harvest Scheduling with Maximum Area Restrictions


Alan T. Murray

Department of Geography, The Ohio State University, 1036 Derby Hall, 154 North Oval Mall, Columbus, OH

Andrés Weintraub

Departamento de Ingenieria Industrial, Universidad de Chile, Casilla 2777, Santiago, Chile




This article examines alternative approaches for representing a forest region to be scheduled for harvesting, where the primary concerns are maximizing return and imposing a maximum contiguous area of disturbance restriction. One approach assumes that any two adjacent management units exceed a regulated maximum area of disturbance. An alternative approach recognizes that management units may be substantially smaller than the maximum area restriction, so simultaneously disturbing two neighboring units does not necessarily represent a maximum area violation. The distinguishing feature of these two approaches is the way in which a forest is spatially represented. A single time period, 351 management unit harvest scheduling problem is utilized to investigate whether analysis results are subject to manipulation when forest representation, and associated modeling, is interpreted in different ways. Empirical results highlight significant economic and spatial variation in harvest schedules when maximum area restrictions are imposed using alternative approaches. Murray and Weintraub 2002. For. Sci. 48(4): 779–789


Key Words

Harvest scheduling, adjacency restrictions, spatial analysis, modifiable areal unit problem.















Modeling loblolly pine canopy dynamics for a light capture model

David W. MacFarlane, Edwin J. Green

Department of Ecology, Evolution and Natural Resources, Rutgers University, New Brunswick, NJ 08903, USA
Andreas Brunner

Danish Forest and Landscape Research Institute, Horsholm, Kongevej 11, Denmark
Ralph L. Amateis
 Department of Forestry, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA


Advances in forest modeling make it possible to estimate light capture for every tree in a stand, and may allow for improvements in modeling stand dynamics. A major difficulty in using such models is that they rely heavily on parameterization of crown characteristics, which presumably differ from stand to stand. We reformulated crown parameters of the tRAYci light capture model for describing crown shape, relative foliar shell thickness and leaf area density (LAD) into generalized equations, which can be used to describe canopy dynamics in even-aged loblolly pine (P. taeda L.) stands. We used parameter equations to model 8 years of change in the canopy of 36, 17-year-old experimental loblolly pine stands, planted under a variety conditions, and estimated annual light capture for every tree over the study period. The results of our analysis suggest that differences in LAD between stands were effectively captured by our parameter estimation methods, but model predictions remained sensitive to parameters describing crown shape and foliar shell thickness. Our results suggest that estimated light capture from tRAYci is somewhat robust to different parameter settings because light apture estimation is strongly influenced by individual tree dimensions, and our methods enhanced this quality. General regression equations were developed for predicting crown characterization parameters from site index, stand age and stand density, but these equations did not fully capture differences in parameter values predicted from stand measurement data. Regression analysis and Cp analysis suggest that planting density was a superior predictor variable for characterizing canopy dynamics when compared to current density. Also discussed in this manuscript are general patterns in canopy dynamics with special references to tRAYci model structure and behavior. McFlarlane and Green et al. 2003. For. Ecol. Manage. 173: 145-168.


Author Keywords

Light-competition; Loblolly pine; Canopy dynamics; Model parameters














Spatial and Temporal Trends of POPs in Norwegian and UK ackground Air: Implications for Global Cycling


S. N. Meijer, W. A. Ockenden

Environmental Science Department, Institute of Environmental and Natural Sciences, Lancaster University, Lancaster LA1 4YQ, UK

E. Steinnes

Department of Chemistry, Norwegian University of Science and Technology, N-7034 Trondheim, Norway

B.P. Corrigan, K.C. Jones

Environmental Science Department, Institute of Environmental and Natural Sciences, Lancaster University, Lancaster LA1 4YQ, UK



Data are presented for PCBs and HCB measured by passive air samplers (SPMDs) along a latitudinal transect from the south of the UK to the north of Norway during 1998-2000. This work is part of an ongoing air sampling campaign in which data were previously gathered for 1994-1996. Comparisons of the masses of chemicals sequestered by the SPMDs during these different time intervals are used to investigate spatial and temporal trends. Results are discussed in the context of sources, long-range atmospheric transport, fractionation/cold condensation, and global clearance processes controlling ambient levels of POPs. Spatial trends show a decrease in absolute sequestered amounts of PCBs with increasing latitude i.e., with increasing distance from the source area. However, relative sequestered amounts of the homologue groups (expressed as a ratio to penta-PCB) show a clear latitudinal trend, with the relative contribution of the lighter congeners increasing with increasing latitude, providing evidence of latitudinal fractionation. Absolute amounts of HCBincrease with latitude, suggesting this compound is undergoing cold condensation. Sequestered amounts of PCBs generally decreased between the two sampling periods by a factor 2-5 over 4 years, suggesting half-lives on the order of 1.7-4 years. The relative rates of decline (1998-2000 data as a percentage of the 1994-1996 data) were compared for different congeners and latitudes. No clear latitudinal trends were found, with all sites/congeners showing a similar marked decline over time to ca. 30% of the former value. We discuss the interpretation of these observations and conclude they imply that the underlying trends of current ambient levels of PCBs in European background air are still largely controlled by primary emissions, rather than recycling/secondary emissions from the major environmental repositories such as soils or water bodies. Meijer and Ockenden et al. 2003. Environ. Sci. Technol.37:454-461















Predicting External Branch Characteristics of Planted Silver Birch ( Betula pendula Roth.) on the Basis of Routine Stand and Tree Measurements


Harri Mäkinen

Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland

Risto Ojansuu

Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301 Vantaa, Finland

Pentti Niemistö

Finnish Forest Research Institute, Parkano Research Station, Kaironiementie 54, FIN-39700 Parkano, Finland




The aim of this study was to develop simultaneous models for external branch characteristics along the stem that could be applied as a part of a growth simulation system. Data were collected from planted pure stands of silver birch ( Betula pendula Roth.) growing on abandoned agricultural land and forest sites of different fertility, with different stand density and age. The data were used to develop generalized linear variance component models for (1) crown ratio, (2) self-pruning ratio, i.e., height of the lowest dead branch divided by the height of the crown base, (3) number of living branches along the stem, (4) total number of branches, (5) diameter of the thickest branch, (6) diameters of smaller branches, and (7) branch angle. The independent variables of the models were restricted to those measured in forest inventories and used for forest management planning purposes. Even though there was bias in predicting some of the branch characteristics in the independent evaluation data set of silver birch, the behavior of the models was logical. No major additional bias was found when the models were applied to downy birch ( Betula pubescens Ehrh.). The models provide a framework for predicting the development of wood quality and the possibilities of using silvicultural treatments to control branch characteristics. Mäkinen and Ojansuu et al. 2003. For. Sci. 49: 301–317.


Key Words

Betula pendula, B. pubescens, branchiness, stand density, wood quality















Estimating Stand Characteristics by Combining Single Tree Pattern Recognition of Digital Video Imagery and a Theoretical Diameter Distribution Model



M. Maltamo

Faculty of Forestry, University of Joensuu, P.O. Box 111, FIN-80101 Joensuu, Finland

T. Tokola

Faculty of Agriculture and Forestry, University of Helsinki, P.O. Box 27, FIN-00014 University of Helsink

M. Lehikoinen

Oy Arboreal Ltd. Niskakatu 1, FIN-80100 Joensuu




This article presents a new method combining pattern recognition of single trees and a theoretical diameter distribution to determine stand characteristics. The applied remote sensing material was digital video imagery. A super-resolution technique was used in order to improve the quality of the video imagery. Tree crowns were identified and crown areas segmented from the super-resolution image. After that, tree diameters were predicted using detected crown areas. However, only large trees (dbh >17 cm) could be recognized from digital video image. Therefore, the theoretical Weibull distribution was predicted to be able to also calculate the number of small trees (dbh <17 cm). The mean characteristics information needed for predicting the parameters of Weibull distribution was obtained from the resulting truncated distribution of large trees. The final estimate of the diameter distribution is a combination of these two parts. The reliability of prediction of stand characteristics considered, i.e., number of stems, stand basal area, and volume was improved with the use of the theoretical diameter distribution model. However, these results should be considered preliminary, because they are based on a small validation data set. According to these results, especially the accuracy of the estimate of the number of stems was increased considerably. This improvement is important when simulating future stand development in forest management planning software packages. Maltamo and Tokola et al. 2003. For. Sci. 49: 98–109.


Key Words

Diameter distribution, optical flow, stand characteristics estimation, superresolution, Weibull-distribution.














Alternative methods for predicting species distribution: an illustration with Himalayan river birds


Stephanie Manel

UPRES 159, Universite de Pau et des Pays de l’Adour, UFR Sciences et Technologie,k Campus Montaury, BP 155 F-64601 Anglet, France

J. M. Dias

UPRES-A-5033 Universite de Pau et des Pays de l’Adour, UFR Sciences et Technologie,k Campus Montaury, BP 155 F-64601 Anglet, France

S.T. Buckton, S.J. Ormerod

Catchment Research Group, School of Biosciences, Cardiff University, PO Box 915, Cardiff CF1 3TL, UK


1. Current emphasis on species conservation requires the development of specific distribution models. Several modelling methods are available, but their performance has seldom been compared. We therefore used discriminant analysis, logistic regression and artificial neural networks with environmental data to predict the presence or absence of six river birds along 180 Himalayan streams. We applied each method to calibration sites and independent test sites. With logistic regression, we compared performance in predicting presence-absence using map-derived predictors (river slope and altitude) as opposed to detailed data from a standardized river habitat survey (RHS).
2. Using the entire calibration data, overall success at predicting presence or absence was only slightly greater using artificial neural networks (89-100%) than either logistic regression (75-92%) or discriminant analysis (81-95%), and on this criterion all methods gave good performance.
3. When applied to independent test data, overall prediction success averaged 71-80%, with logistic regression marginally but significantly out-performing the other methods. Encouragingly for researchers with limited data, model performance in jack-knife tests faithfully represented performance in more rigorous validations where calibration (n = 119) and test sites (n = 61) were in separate geographical regions.
4. All three methods predicted true absences (83-92% success) better than true presences (31-44%). Results from logistic regression were the most variable across species, but positive prediction declined with increasing species rarity in each method.
5. Applications with logistic regression illustrated that significant habitat predictors varied between data sets within species. Hypotheses about causal effects by habitat structure on distribution were thus difficult to erect or test. Logistic regression also showed that detailed data from the river habitat survey substantially improved positive prediction by comparison with prediction using slope or altitude alone.
6. We conclude that discriminant analysis, logistic regression and artificial neural networks differ only marginally in performance when predicting species distributions. Model choice should therefore depend on the nature of the data, on the needs of any particular analysis, and on whether assumptions for each method are satisfied. All three methods share drawbacks due to systematic effects by species rarity on performance measures. They also share limitations due to the correlative nature of survey data often used for model development at the spatial scales required in macro-ecology and conservation biology. Tests with independent data, using a wider range of performance measures than those used traditionally, will be important in examining models and testing hypotheses for such applications.
Manel and Dias et al. 1999. J. Appl. Ecol. 36: 734-747.













Comparison of Three Techniques Used to Measure Diffusive Gas Exchange from Sheltered Aquatic Surfaces


Cory J. D. Matthews, Vincent L. St. Louis

Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada T6G 2E9,

Raymond H. Hesslein

and Department of Fisheries and Oceans Canada, Freshwater Institute, 501 University Crescent, Winnipeg,

Manitoba, Canada R3T 2N6



Three approaches commonly used to quantify diffusive gas exchange across aquatic surfaces were compared in a densely treed, low-wind environment. Diffusive surface fluxes of carbon dioxide (CO2) and methane (CH4) from a small boreal reservoir were estimated using (i) surface water concentrations, the thin boundary layer (TBL) equation, and gas transfer velocities (k) calculated using sulfur hexafluoride (SF6); (ii) surface water concentrations, the TBL equation, and k estimated from wind speed; and (iii) static floating chambers (FCs). Comparisons were made during three different 10-day intervals (August 2000, June and September 2001). CO2 and CH4  fluxes estimated from SF6-derived k were on average 1-3 times greater than those determined from wind-estimated k. Overall agreement between FC CO2 and CH4 flux estimates and those based on SF6 and wind speed derived k values was much weaker, with FC CO2 and CH4  flux estimates ranging from -9 to 23 times those based on SF6 and wind-estimated k values. Chamber deployment likely enhanced gas transfer through disturbance of the surface boundary layer, and results of this study suggest that caution must be exercised concerning the use of FCs on very still water surfaces. Furthermore, findings of this study contradict the common belief that use of wind speed to approximate k is inappropriate for small bodies of water characterized by low winds and surface obstructions. Matthews and Louis et al 2003. Environ. Sci. 37: 772-780.















Empirical Yields of Timber and Forest Biomass in the Southeast

Joe P. McClure, Herbert A. Knight

Forest Inventory and Analysis in the Southeast Asheville, North Carolina


Measurements and classifications recorded at 24,775 Forest Survey plots established randomly throughout the Southeast comprise a vast source of information on timber stand development. Empirical yield tables developed from this source are reported for major forest types in the Region. These tables also serve as guides to yields of forest biomass by tree size and species groups. McClure and Knight 1984. USDA Forest Service Research Paper SE-245



Southeast, yield tables, forest biomass, guides to yields in the Region expressed  in terms of forest biomass.
















Estimating the Uncertainty In Diameter Growth Model Predictions and Its Effects on The Uncertainty of Annual Inventory Estimates

Ronald E. McRoberts, Veronica C. Lessard

USDA Forest Service, North Central Research Station, 1992 Folwell Avenue, St. Paul, MN 55108



Uncertainty in diameter growth predictions is attributed to three general sources: measurement error or sampling variability in predictor variables, parameter covariances, and residual or unexplained variation around model expectations. Using measurement error and sampling variability distributions obtained from the literature and Monte Carlo simulation methods, the uncertainty in 10-year diameter growth model predictions is estimated as are its effects on annual basal area estimates obtained using an annual inventory system. The results indicate that although annual diameter growth is difficult to predict precisely, the effects of the uncertainty in the growth predictions are greatly attenuated when diameter estimates are aggregated to estimate plot basal area and mean basal area over all plots. McRoberts and Lessard 2000. Paper presented at the Second Annual Forest Inventory and Analysis (FIA) Symposium, Salt Lake City, UT, October 17–18, 2000.














Interactive Effects of Fire And Microhabitat on Plants of Florida Scrub


Eric S. Menges

Archbold Biological Station P.O. Box 2057, Lake Placid, Florida 33862 USA

 Christine V. Hawkes

Department of Biology, Leidy Laboratories, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6018 USA



Fire, microhabitat, and their interactions affect Florida scrub ecosystems and their plant species. Concepts of vegetation change in the Florida upland landscape have followed successional theory, with recent models emphasizing the resilience of Florida scrub to fire and the interactive effects of the vegetation and fire regime. We extend these models by incorporating greater complexity in vegetation types and emphasizing that departures from modal fire frequencies may alter vegetation. In particular, fire exclusion leads to structural and compositional changes that, in turn, alter vegetation changes following the reintroduction of fire.

Individual species responses to fire can be categorized by the demographic mechanisms of the response (e.g., resprouting, clonal growth, seedling recruitment) and by typical patterns of abundance during fire-free intervals. Various types of scrub differ in these life-history traits. For example, xeric rosemary scrub supports more herbs, more endemics, more specialized species, and more seeders increasing in abundance between fires as compared to less xeric scrubby flatwoods. Several of these species are demonstrated specialists for gaps, which are more abundant and persistent in rosemary scrub than in scrubby flatwoods. In scrubby flatwoods, patterns of species abundance are explainable by time since fire and the presence of gaps, and sprouters are more successful than seeders between fires. In rosemary scrub, where gaps remain long after fire, species abundance patterns reflect only gap abundance, and seeders are especially successful between fires. Because fires create or enlarge gaps that are then closed between fires (especially in less xeric habitats), gap specialists may be sensitive to both fire and microhabitat. Alteration of the modal fire regime is hypothesized to affect the proportion of sprouters and seeders, microsite diversity, and the long-term local persistence of species with different specializations for postfire response and between-fire competitive abilities. Metapopulation dynamics in a landscape patterned by edaphic gradients, a patchy and variable disturbance regime, and small-scale gap dynamics produce varied spatial and temporal patterns in species’ abundances. Menges and Hawkes 1998. Ecol. Appl. 8: 935-946.

Key words

Disturbance; fire and microhabitat effects on plants; fire frequency; Florida (USA) scrub ecosystems; gap dynamics; landscape; microhabitat importance; microsite diversity; rosemary scrub; sand pine scrub; scrubby flatwoods; succession, theory and model.














Spatial Smoothing of Geographically Aggregated Data, With Application to the Construction of Incidence Maps


Hans-Georg Muller

Division of Statistics, University of California, Davis, CA 95616

Ulrich Stadtmuller

Department of  Mathematics, Universital Ulm, 89069 Ulm, Germany

Farzaneh Tabnak

California Department of Health Services, Office of AIDS, HIV-Epidemiology Branch, Sacramento, CA 94234



We address the commonly encountered situation in spatial statistics where data such as counts of incidences of a certain disease are available only in geographically aggregated form. We develop fairly general models and propose a modified version of the locally weighted least squares method to recover the unknown smooth spatial function that is assumed to generate the observations. In the special case of count data, the target function is the intensity function, conditional on the total number of observations. Our method avoids the arbitrariness of selecting a point within each geographic area at which the measurement for the whole area is supposed to be located. We derive basic asymptotic properties, and apply our methods to acquired immune deficiency syndrome (AIDS) incidence data in San Francisco for 1980-1992, where counts are available aggregated over zip code areas. Muller and Stadtmuller et al. 1997. J. Am. Stat. Assoc. 92:  61-71.














Total aboveground biomass in central Amazonian rainforests: a landscape-scale study

Henrique E. M.

Biological Dynamics of Forest Fragments Project, National Institute for Amazonian Research (INPA), C.P. 478, Manaus AM 69011-970, Brazil

William F. Laurance
 Biological Dynamics of Forest Fragments Project, National Institute for Amazonian Research (INPA), C.P. 478, Manaus AM 69011-970, Brazil and Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of, Panama


Amazonian forests play a key role in the global carbon cycle, but there is much uncertainty about the quantity and distribution of carbon stored in these forests. We quantified total aboveground dry biomass (TAGB) in undisturbed central Amazonian rainforests, based on detailed estimates of all live and dead plant material within 20 1 ha plots spanning an extensive (ca. 1000 km2) study area. TAGB values in our study area were very high, averaging 397.7±30.0 Mgha-1. The most important component of aboveground biomass was large ( greater-than or equal to10 cm diameter-at-breast-height (DBH)) trees, which comprised 81.9% of TAGB, followed by downed wood debris (7.0%), small trees, saplings, and seedlings (<10 cm DBH; 5.3%), lianas (2.1%), litter (1.9%), snags (1.5%), and stemless palms (0.3%). Among large trees, aboveground biomass was greatest in intermediate-sized (20–50 cm DBH) stems (46.7% of TAGB), with very large ( greater-than or equal to60 cm DBH) trees also containing substantial biomass (13.4% of TAGB). There were no significant correlations between large tree biomass and that of any other live or dead biomass component. An analysis based on the variability of our samples suggested that just 3–4 randomly positioned 1 ha plots would be sufficient to provide a reasonable estimate of mean TAGB in a landscape such as ours (with 95% confidence intervals being <10% of the mean). This suggests that efforts to quantify Amazon forest biomass should be extensive rather than intensive; researchers should sample many geographically separate areas with a few plots each, rather than sampling a small number of areas more intensively. Henrique and Laurance 2002. For. Ecol. Manage. 168: 311-321.


Author Keywords

Amazon basin; Biomass; Carbon cycle; Carbon storage; Global warming; Terra-firme forest; Tropical rainforest














The growth potential of downy birch (Betula pubescens (Ehrh.)) in Ireland

M. Nieuwenhuis, F. Barrett

Department of Forestry, University College Dublin, Belfield, Dublin 4, Ireland

Birch in Ireland has long been regarded a timber species of minor importance, and it is noted more often for its invasiveness in young coniferous forests and clearfelled areas than for its potential as a commercial forestry species. While research on other native hardwood species such as oak or ash has been ongoing for a number of years, very little is known about the Irish birch resource. The lack of quantitative data relating to height growth, diameter growth and volume increment of birch in this country is of particular concern. The objective of this study was to examine the growth potential of birch in Ireland. Following a field survey, eight well-stocked, unthinned birch stands were selected for inclusion in the study. All of the selected stands were determined to be downy birch. Following analysis of sample tree disc sections, two stands were excluded (because of indistinct annual rings) and the study was restricted to the six remaining stands. A total of 100 sample trees were felled at the six sites. Tree ring data were collected from a total of 1333 sample tree disc sections. Using these ring data, the historic patterns of radial growth at breast height, height growth and volume growth of the six stands were reconstructed, examined and analysed in detail. The results showed that for well-stocked, unthinned, even-aged stands the period of maximum radial growth, and therefore diameter growth, occurred between the ages of 5 and 20 years. The fastest growing tree achieved a diameter of 25 cm in 32 years. It is suggested that for the stands included in this study, the lack of management, in particular the lack of adequate thinning, will have resulted in excessive crown competition and consequently reduced diameter growth. Maximum height increment occurred before the age of 20 years and fast growing trees achieved a height growth of > 1 m per year during this period. The results showed that a well-stocked, unthinned downy birch stand can achieve a standing volume (under-bark) of 200 m3 ha-1 in 42 years. While some of the stands included in the study had not reached the age of maximum mean annual increment, comparison with the Forestry Commission yield models showed that stands of downy birch in Ireland can achieve a yield class of 8 and, given the correct thinning regime, total recovered volume production could possibly be raised to that equivalent with yield class 10. Nieuwenhuis and Barrett et al. 2002. For. 75: 75-87.













Height growth of black spruce in British Columbia


Gordon D. Nigh1

Research Branch, British Columbia Ministry of Forests, P.O. Box 9519, Stn. Prov. Govt., Victoria, British Columbia V8W 9C2

Pavel V. Krestov

Institute of Biology and Pedology, Russian Academy of Sciences, Far Eastern Branch, Vladivostok, Russia V690022

Karel Klinka

University of British Columbia, Department of Forest Sciences, 3041 – 2424 Main Mall, Vancouver, British Columbia V6T 1Z4



Black spruce (Picea mariana (Mill.) B.S.P.) is a boreal species that occurs extensively across the northern half of British Columbia. Forest managers require better growth and yield information for black spruce given the anticipated increase in demand for wood in the northern part of the province. The purpose of this study was to develop height-age models for black spruce. Ninety-one stem analysis plots were established in the BWBS and SBS biogeoclimatic zones. Three black spruce site trees from each plot were stem analyzed and the data were converted into height-age data. A conditioned log-logistic function was fit to the data. Indicator variables were used to test for differences in height growth between the sampled subzones. Although the warm subzones had different height growth patterns than the cool subzones, there was general agreement among the height-age models from British Columbia, Alberta, and New Brunswick up to about age 100. Nigh and Krestov et al. 2002. For. Chron. 78: 306-313.


Key Words

Biogeoclimatic zones, height-age models, logistic function, site index, stem analysis













A Comparison of Three Modelling Approaches for Large-Scale Forest Scenario Analysis in Finland


Tuula Nuutinen

Finnish Forest Research Institute, Joensuu Research Centre, Box 68, FIN-80101 Joensuu, Finland

Seppo Kellomäki

University of Joensuu, Box 111, FIN-80101 Joensuu, Finland



Forests play an important role in the sequestration of carbon dioxide and the storage of carbon. The potential and efficiency of mitigation options in forestry have been studied using large-scale forestry scenario models. In Finland, three models have been applied in attempts to estimate timber production and related carbon budgets. In this study, these models are compared. The oldest, MELA, was designed in the 1970s for the regional and national analysis of timber production. The European Forest Information Scenario Model, EFISCEN, originally a Swedish area matrix model, was developed in the early 1980s. SIMA, a gap-type ecosystem model, was utilized in the 1990s for regional predictions on how the changing climate may affect forest growth and timber yield in Finland. In EFISCEN, only the development of growing stock is endogeneous because the assumptions on growth, and the removal and rules for felling are given exogeneously. In the SIMA model, the rules for felling are exogeneous but the growth is modelled based on individual trees reacting to their environment. In the MELA model, the management of forests is endogeneous, i.e. the growth, felling regimes and the development of growing stock are the results of the analysis. The MELA approach integrated with a processbased ecosystem model seems most applicable in the analyses of effective mitigation measures compatible with sustainable forestry under a changing climate. When using the scenarios for the estimation of carbon budget, the policy makers should check that the analyses cover the whole area of interest, and that the assumptions on growth and management together with the definitions applied correspond with the forestry conditions in question. Nuutinen and Kellomaki 2002. Silva Fenn. 35: 299-308.


Carbon budget, forestry model, scenario modeling, MELA, EFISCEN, SIMA
















Satellite imagery as a tool for monitoring species diversity: an assessment

Harini Nagendra

Center for Ecological Sciences, Indian Insttitute of Science, Bangalore 560012, India

Madhav Gadgil

Center for Ecological Sciences, Indian Insttitute of Science, Bangalore 560012, India and Jawaharlal Nehru Center for Advanced Scientific Research, Jakkur PO, Bangalore 560064, India


1. A landscape of 5 × 5·5 km in the Karnataka region of the Western Ghats of India was mapped into seven landscape element types, using field identification of types as well as supervised and unsupervised classification of satellite imagery.
2. Plant communities distributed in these landscape element types were surveyed in the field using 246 quadrats of 10 × 10 m, in order to assess whether these types could be distinguished in terms of species composition. All angiosperms excluding grasses, which could not be identified accurately in the field, were recorded for this purpose.
3. Landscape element types identified in the field harbored significantly distinctive sets of species of flowering plants, and were also by and large distinctive in terms of their species richness.
4. Landscape element types could be identified accurately on the basis of supervised classification: the types thus demarcated harboured distinctive sets of flowering plants.
5. Landscape element types coupled to satellite imagery could then be used to organize a programme of monitoring biodiversity.
6. Unsupervised classification of satellite imagery did not permit classification of landscape element types with a high enough level of accuracy. In consequence, the demarcated landscape element types did not harbor significantly distinctive sets of species of flowering plants. Unsupervised classification is therefore not appropriate in a programme of monitoring biodiversity. Nagendra and Gadgil 1999. J. Appl. Ecol. 36: 388-397.



Biodiversity; India; landscape ecology; remote sensing; Western Ghats













Weight and Volume Determination for Planted Loblolly Pine in North Louisiana 

Ray A. Newbold

Louisiana Tech University, School of Forestry, Ruston, LA

V. Clark Baldwin, Jr.

U.S. Department of Agriculture, Forest Service, Southern Research Station, Asheville, NC

Gary Hill

Willamette Industries, Inc., Ruston, LA



The objective of this study was to assess the variability in weight-to-volume relationships in loblolly pine (Pinus taeda L.) plantations and to determine predictability based on stand age, site quality, and/or tree size. Tree ages ranged from 11 to 40 years, with diameters to 21 inches and heights to 91 feet. Measured site indices ranged from 4.5 to 72 at base age 25. A total of 75 planted loblolly pine trees were felled and processed to assess the variability in bole weight to volume relationships. Cubic volume, green weight, and dry weight relationships were investigated; and the predictability of these variables with respect to age, site index, and tree size was determined. Newbold and Baldwin, Jr. et al. 2001. USDA Forest Service Southern Research Station Research Paper SRS-26.



Loblolly pine, Pinus taeda, plantation, volume, weight.















Site Index Conversion Equations for Mixed Trembling Aspen and White Spruce Stands in Northern British Columbia


Gordon Nigh

Ministry of Forests, Research Branch, P.O. Box 9519, Stn. Prov. Govt., Victoria, BC, Canada V8W 9C2



White spruce and trembling aspen are two important commercial species in British Columbia. They often grow in association, particularly in the Boreal White and Black Spruce and Sub-Boreal Spruce biogeoclimatic zones. Site index conversion equations are useful for estimating the site index of one species from the site index of another species. This study fills a need for site index conversion equations for mixed spruce/aspen stands. Seventy 0.01 ha study plots were established in mixed spruce/aspen stands. One site tree of each species was selected from each plot. The height and breast height ages of the site trees were measured and the site index was estimated with these data. The correlation between the site index of spruce and aspen was 0.6. Geometric mean regression was used to estimate the parameters of a linear site index conversion equation. The analysis did not reveal any differences in the conversion equations across the three major biogeoclimatic units (BWBSmw1, BWBSmw2, and SBS) that were sampled. Therefore, only one conversion equation is required. Nigh 2002. Silva Fenn. 36: 789-797.



mixed species, site index, trembling aspen, white spruce

















Scots pine and Norway spruce stands responses to annual N, P and Mg fertilization

Petter Nilsen

Norwegian Forest Research Institute, Høgskoleveien 12, N-1432, Ås, Norway

Gunnar Abrahamsen
Department of Soil and Water Sciences, Agricultural University of Norway, Post Box 5028, N-1432, Ås, Norway


Results from two fertilizer experiments in coniferous forest in south and southeast Norway with applications of nitrogen (N), magnesium (Mg) and phosphorous (P) are presented. A Scots pine stand has been fertilized annually for 9 years and one Norway spruce stand has been fertilized annually for 4 years. The aim of the study has been to investigate to what extent N fertilization in middle-aged stands of Scots pine and Norway spruce stimulates tree growth, and whether Mg and P counteract possible induced nutrient imbalances caused by high N doses. Both stands responded strongly to N addition and application of 30 and 90 kg N ha-1 yr-1 resulted in a relative volume increment of 150 and 250%, respectively, compared to control. The increment effect in the pine experiment ceased after 4 years, but the difference between the two N doses was still significant after 9 years. The application of 1.5 kg Mg ha-1 yr-1 had just a slight significant positive effect on volume increment in two of the 9 years in the pine experiment, while no effect of 5.3 kg P ha-1 yr-1 on volume increment was found. Needle nutrient concentrations were mainly affected by the N treatment and concentrations above 30 mg g-1 was detected in the pine experiment. The concentration of P, Mg and K was negatively affected by the highest N dose in the spruce experiment, but not in the pine experiment. The imbalanced nutritional status created by N application was partly reduced by the P and Mg addition, but no substantial effect on tree growth has been detected so far. The stands have a large potential for accumulating N in the standing biomass and judged from the effect on nutrient concentrations and growth, Mg might be the next element that could limit tree growth by a continued high N atmospheric input. Nilson and Abrahamsen 2003. For. Ecol. Manage. 174: 221-232.


Author Keywords

Boreal; Growth response; Nutrient concentration; Nutrient imbalance; Picea abies; Pinus sylvestris













A Comparison of Compatible and Annual Growth Models


Norihisa Ochi, Quang V. Cao

School of Renewable Natural Resources, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, LA  70803



Compatible growth and yield models are desirable because they provide the same growth estimates regardless of length of growth periods. However, the compatibility constraints restrict the number of possible models. This restriction might be overcome by using models that predict annual stand growth based on periodic measurements. The advantages of this approach are (1) the flexibility allowed in building annual growth models without constraints, and (2) the step-invariance property maintained by these models. An annual growth model was developed in this study that predicts yield based on information from the previous year. For 162 plots from the Southwide Seed Source Study of loblolly pine (Pinus taeda L.), the annual growth model provided better predictions of stand survival, basal area, and volume than two compatible growth models. Ochi and Cao 2003. For. Sci. 49(2): 285–290.


Key Words

Compatible growth and yield models, step-invariant models, loblolly pine, Pinus taeda.















Allometric Modeling of Plant Root Growth and Its Application in Rhizosphere Remediation of Soil Contaminants



Paul E. Olson

Biology Department, Colorado State University, E414 A/Z Building, Fort Collins, Colorado 80523

Tom Wong

Union Carbide Corporation, Subsidiary of TDCC, P.O. Box 471, Texas City, Texas 77592-0471

Mary Beth Leigh, John S. Fletcher

Department of Botany and Microbiology, University of  Oklahoma, 770 Van Vleet Oval, Room 136,

Norman, Oklahoma 73019



Allometric curves relating tree trunk diameter to root biomass, depth, and breadth were compiled for mulberry (Morussp.). The curves were based on statistical analyses of measurements made on 29 different-sized trees ranging in age from 2 to 15 yr that had grown from seed in a naturally revegetated former sludge basin containing polyaromatic hydrocarbons. Over a 15-yr period, the curves indicate that the fine root biomass (<1.5 mm diameter) increases 60-fold and, under the right circumstances, can be a part of a root system that reaches a 2-m depth. The fine roots of mulberry were shown to produce several flavonoid compounds at concentrations (ranging from 94 to 525 Ìg/cm3) known to support the growth of organisms capable of degrading xenobiotics. Recognizing the root system as the driver of rhizoremediation, allometry curves presented in this paper can be used to quantify the magnitude of the driver (root system) without damaging plants during the course of a multiyear field study. Olsen and Wong et al. 2003. 

Environ. Sci. Technol. 37: 638-643.















A landscape-scale study of bumble bee foraging range and constancy, using harmonic radar


J.L. Osborne

Department of Entomology and Nematology, IACR-Rothamsted, Harpenden, Hertfordshire AL5 2JQ, UK

S.J. Clark

Department of Statistics, IACR-Rothamsted, Harpenden, Hertfordshire AL5 2JQ, UK

R.J. Morris, I.H. Williams

Department of Entomology and Nematology, IACR-Rothamsted, Harpenden, Hertfordshire AL5 2JQ, UK

J.R. Riley, A.D. Smith, D.R. Reynolds, A.S. Edwards

NRI Radar Unit, University of Greenwich, North site, Leigh Sinton RDS, Malvern, Worcestershire WRI4 1LL, UK



1. Bumble bees play a vital role in the pollination of many crops and wild flowers, and plans for their conservation require a knowledge of the dynamics and spatial scale of their foraging flights, which are, at present, poorly understood.
2. We investigated the foraging range and constancy of two colonies of bumble bees Bombus terrestris L. on a mixed arable farm using harmonic radar, which has a unique capability to record the trajectories of insects flying at low altitude in the field.
3. Foraging bees were fitted with lightweight radar transponders and tracked as they flew to and from the nest to forage. The resulting tracks gave information on length, direction and straightness of foraging routes. Superimposition onto a map of the foraging landscape allowed interpretation of the bees' destinations in relation to the spatial distribution of forage.
4. Outward tracks had a mean length of 275·3 ± 18·5 m (n = 65) and a range of 70-631 m, and were often to forage destinations beyond the nearest available forage. Most bees were constant to compass bearing and destination over successive trips, although one bee was tracked apparently switching between forage patches. Both outward and return tracks had a mean straightness ratio of 0·93 ± 0·01 (n = 99). The bees' ground speeds ranged from 3·0 m s-1 to 15·7 m s-1 (n = 100) in a variety of wind conditions.
5. The results support the hypothesis that bumble bees do not necessarily forage close to their nest, and illustrate that studies on a landscape scale are required if we are to evaluate bee foraging ranges fully with respect to resource availability. Such evaluations are required to underpin assessments of gene flow in bee-pollinated crops and wild flowers. They are also required when making decisions about the management of bees as pollinators and the conservation of bee and plant biodiversity.
Osborne and Clark et al. 1999.  J. Appl. Ecol. 36: 519-533.



Bee movement; flight trajectory; foraging constancy; fragmented habitat; radar tracking














White Pine Site Index for the Southern Forest Survey


Bernard R. Parresol

Southern Forest Inventory, Monitoring, and Analysis Program (SFIMAP), U.S. Department of Agriculture, Forest Service, Southern Research Station, Asheville, NC 28804

John S. Vissage

Forest Inventory and Analysis (FIA) unit, U.S. Department of Agriculture, Forest Service, Southern Research Station, Starkville, MS 39760



A base-age invariant polymorphic site index equation was used to model the white pine (Pinus strobus L.) site-quality data provided by Frothingham (1914). These data are the accepted standard used by the Southern Forest Inventory and Analysis unit of the U.S. Department of Agriculture, Forest Service. An all possible growth intervals data structure was used, and autocorrelation parameters were incorporated into the site index model. It has recently been shown that these measures are necessary to obtain unbiased, efficient parameter estimates. The model is invertible; hence site index can be explicitly determined without the need for a numerical evaluation procedure. The site index model can be solved to provide an equation for any base age, hence it is applicable regardless of the choice of rotation age. Site index curves are graphed for base ages 25 and 50 years, and example calculations are provided. Parresol and Vissage 1998. United States Department of Agriculture Forest Service Southern Research Station Research Paper SRS-10



Autocorrelation, base-age invariant, Pinus strobus, polymorphic
















Self-thinning and stockability of the circumboreal aspens (Populus tremuloides Michx., and P. tremula L.)


Perala, D.A.

USDA Forest Service, North Central Research Station, 1831 Highway 169 East, Grand Rapids, MN 55744

Leary, R.A.

USDA Forest Service, North Central Resaerch Station, 1992 Folwell Ave., St. Paul, MN 55108

Cieszewski, C.J.

School of Forest Resources, University of Georgia, Athens, GA 30602



Examines the stand diameter-density relationship of aspen across North America and Scandanavia, and how the level of this relationship might be climatically influenced. Perala and Leary et al. 1999. Research Paper NC-335. St. Paul, MN: U.S. Dept. of Agriculture, Forest Service, North Central Research Station.


Key Words

Size-density, limiting relationship, carrying capacity, average mass density















Impacts of Rotation Age Changes on Growth/Removals Ratios



Stephen P. Prisley

Department of Forestry, Virginia Tech, Blacksburg, Virginia 24061

Andrew J. Malmquist

Forest Technology Group, 125 Crosscreek Drive, Summerville, SC 29485.



When forest managers and policymakers wish to assess the ability of a given forest resource to support a sustainable level of timber harvests, they frequently use growth/removals ratios (G/R) developed from forest inventory data. Recently published inventory data for forests of the southern United States have documented numerous states in which softwood harvests exceed softwood growth, raising concern over the sustainability of this critical resource. At the same time, forest managers in the South have been investing in a wide range of practices that have dramatically increased the growth rates for softwood plantations. As these growth increases are verified in the field, forest managers respond accordingly with adjustments to management regimes, including shortening of rotation lengths. This, in turn, means that the area of forest harvested annually must increase in a given forest estate to approach a regulated forest condition. The Timber Inventory, Growth, and Removals model (TIGR) is a spreadsheet model developed to evaluate the impact of shortening rotation length on the growth/removals ratios for managed forests. The model demonstrates that a temporary imbalance of removals over growth results when the rotation age is shortened. Hence, managers and policymakers should use caution when making inferences or public claims about sustainable harvest levels from growth/removals ratios alone. If the public has been convinced that G/R ratios greater than 1.0 imply sustainable harvests, then difficult explanations will be required when the G/R ratio drops below 1.0 . Prisley and Malmquist 2002. South. J. Appl. For. 26:72–77.


Key Words

Sustainability, forest inventory, inventory projection, modeling.
















Site Preparation Effects on 20 Year Survival and Growth of Douglas-Fir (Pseudotsuga menziesii) and on Selected Soil Properties


Kathryn B. Piatek

SUNY College of Environmental Sciences and Forestry, Syracuse, NY 13210

Constance A. Harrington, Dean S. DeBell

USDA Forest Service, Pacific Northwest Research Station, 3625 93rd Ave. SW, Olympia, WA 98512-9193



Long-term effects of site preparation on tree performance and soil properties are not well known. Five site preparation treatments were evaluated to determine how they affected survival and growth of Douglas-fir 3, 10, and 20 yr after planting, and soil bulk density, C, N, P, and organic matter concentrations at 0 to 20 cm soil depth 21 yr after planting. The site preparation treatments were imposed following logging of three harvest units of old-growth forest on a volcanic soil in southwestern Washington; the units were logged to leave 17, 38, and 53 ton/ha of woody residue. The site preparation treatments were hand-pile-and-burn, machine-pile-and-burn, scarification, broadcast burn, and control. Mean survival ranged from 86% at age 3 to 70% at age 20, and average tree heights at 3, 10, and 20 yr were 0.6, 4.1, and 11.7 m. The scarification treatment had the best growth; at age 20, its average tree was 21% taller, 26% larger in diameter, and 82% greater in volume than the control. The hand-pile-and-burn treatment did not differ from the control in tree growth; the machine-pile-and-burn and broadcast burn treatments were intermediate in their growth response.

Average soil bulk density was 0.74 g/cm3, organic matter concentration was 118 g/kg, and C, N, and P concentrations were 49, 1.6, and 0.7 g/kg with no significant treatment effects. Site preparation may have benefited growth of the trees on these units by decreasing competition from invading and regrowing vegetation, increasing nutrient availability, or increasing soil temperature. Piatek and Harrington et al. 2003. West. J. Appl. For. 18: 44–51.

Key Words

Long-term site productivity, soil nutrients, coarse woody debris, prescribed fire.  














Exploring density-dependent relationships in demographic parameters in populations of birds at a large spatial scale


Emmanuel Paradis, Stephen R. Baillie

British Trust for Ornithology, The Nunnery, Thetford, Norfolk, IP 24 2PU, UK

William J. Sutherland

School of Biological Sci., Univ. of East Anglia, Norwich, NR4 7TJ, UK

Richard D. Gregory

British Trust for Ornithology, The Nunnery, Thetford, Norfolk, IP 24 2PU, UK




The importance of density-dependent processes in natural populations is widely accepted, but the issue of the shape of density-dependent relationships (such as influenced by vagueness, or time-delay) remains unresolved. We explored the density dependent relationships in demographic parameters for 12 species of birds in Britain using large-scale, long-term data sets. We predicted that a negative relation between density and demographic parameters should be observed for the stable species, whereas the decreasing or increasing species should display a positive relation if the environment changes progressively through time bringing about a continuous change in density dependence. Our prediction was verified for nine species out of 12; however, we observed, for the three remaining species, a significant decrease of survival rates through time that seems to be involved in a long-term population decline. In all cases where a density-dependent relation was found, we observed an important variance around the relation. In one case, we showed that this variance increased significantly with density. We found evidence for time-delayed effects of density dependence both for survival and breeding performance. In two species, our results suggest the existence of complex interactions (compensatory mechanisms) between survival and breeding performance or between the different components of breeding performance. Paradis and Baillie et al 2002. Oikos 97: 293–307.















Assessing tree and stand biomass: A review with examples and critical comparisons

Bernard R. Parresol

USDA Forest Setvice, Southem Research Station, P.O. Box 2680, Asheville, NC 28802



45 (4): 573-593 NOV 1999

There is considerable interest today in estimating the biomass of trees and forests for both practical forestry issues and scientific purposes. New techniques and procedures are brought together along with the more traditional approaches to estimating woody biomass. General model forms and weighted analysis are reviewed, along with statistics for evaluating and comparing biomass models. Additivity and harmonization are addressed, and weight-ratio and density-integral approaches are discussed. Subsampling methods on trees to derive unbiased weight estimates are examined, and ratio and difference sampling estimators are considered in detail. Error components for stand biomass estimates are examined. This paper reviews quantitative principles and gives specific examples for prediction of tree biomass. The examples should prove useful for understanding the principles involved and for instructional purposes. Parresol 1999. For. Sci., 45: 573-593.

Author Keywords
model forms, weighting, selection criteria, subsampling, error components

Key Words Plus
pipe model-theory, regression-models, leaf-area, allometric relationships, aboveground biomass, tropical forests, pine plantations, foliage biomass, sapwood area, volume













The carbon pool in a British semi-natural woodland

G.L. Patenaude

Environmental Change Institute, University of Oxford, 1A Mansfield Road, Oxford OX1 3SZ, England

B.D.J. Briggs

Oxford Forestry Institute, Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, England

R. Milne

Center of Ecology and Hydrology, Bush Estate, Penicuik, Midlothian EH26 0QB, Scotland

C.S. Rowland1, T.P. Dawson

Environmental Change Institute, University of Oxford, 1A Mansfield Road, Oxford OX1 3SZ, England

S.N. Pryor

Oxford Forestry Institute, Department of Plant Sciences, University of Oxford, South Parks Road, Oxford OX1 3RB, England



A comprehensive, generally non-destructive quantification of carbon in all significant above- and below-ground forest components for five contrasting stands was undertaken in Monks Wood, southeast England. The total carbon content of the five selected stands varied from 346 to 616 t ha–1. The mean carbon content of the forest components was approximately 2 t ha–1 for deadwood, 3 t ha–1 each for foliage and ground vegetation/litter, 18 t ha–1 for understorey shrubs and small trees, 28 t ha–1 for all roots, 78 t ha–1 for overstorey trees, and 335 t ha–1 for soils. The results of this study suggest that if the stands sampled at Monks Wood were representative of broadleaved woodlands in Great Britain and, if understorey vegetation were considered, they would contain 92.6 Mt carbon. This contrasts with a previous estimate of 61.9 Mt carbon, which excluded understorey vegetation. The results highlight the importance of broadleaved woodlands as carbon stores and will be informative to current and future initiatives for developing British woodlands to offset greenhouse gas emissions. Patenaude and Briggs et al. 2003. For. 75:109-119.














Image segment-based spectral features in the estimation of timber volume

Anssi Pekkarinen
Finnish Forest Research Institute, Unioninkatu 40 A, FIN-00170, Helsinki, Finland


Plot- and stand-level errors associated with satellite image-based multisource forest inventory (MSFI) applications have been relatively high. The reasons suggested for that are related to the limited spatial resolution of the image material. The introduction of very high spatial resolution (VHR) images to MSFI applications should, therefore, diminish these errors. The use of VHR images is, however, problematic, because pixel-by-pixel analysis methods are no longer applicable. The paper presents an image segment-based approach to the determination of feature extraction and image analysis units. The study was carried out in Southern Finland and employed a spectrally averaged imaging spectrometer (AISA) image and field data gathered from sample plots. A two-phase segmentation method was applied and a large number of segment-based spectral features was extracted and used as input to a feature selection procedure. Forward selection based on an improvement of RMSE was applied. The performance of segment-based features (SF) was compared to that of reference features (RF) extracted from square-shaped windows. The estimation results revealed that even though the applied segmentation method succeeded well in the determination of units of feature extraction and image analysis, the differences between the performance of SF and RF were small and the plot-level estimation errors remained high. The study suggests that large estimation errors are due to the local nature of the field data and may be diminished using data that is representative at the segment level. Pekkarinen 2002. Remote Sens. Environ. 82: 349-359.














Predictive models of whitebark pine mortality from mountain pine beetle

Dana L. Perkins

Research Ecologist, Pacific Northwest Research Station, 1401 Gekeler Lane, La Grande, OR 97850, USA

David W. Roberts
Department of Forest Resources, Utah State University, Logan, UT 84321, USA


Stand-level and tree-level data collected from whitebark pine (Pinus albicaulis Engelm.) stands in central Idaho were used to estimate the probability of attack and mortality of whitebark pine caused by mountain pine beetle (Dendroctonus ponderosae Hopkins) (Coleoptera: Scolytidae). Logistic regression models were calibrated from reconstructed pre-epidemic stand conditions and post-epidemic mortality levels resulting from a widespread mountain pine beetle outbreak that occurred from 1909 to 1940. Basal area (m2/ha) and stand density index (SDI) were stand-level variables that completely differentiated stands into attacked or non-attacked categories. Whitebark pine stands with basal areas above 10 m2/ha (44 ft2/acre) or with an SDI above 80 had a 100% probability of being attacked. Tree diameter, basal area per 0.04 ha, trees per 0.04 ha, and number of stems in a tree cluster were significant predictors of individual tree attack (p less-than or equal to0.001) in logistic regression. The tree-level model may be used to estimate anticipated cumulative mortality in currently or potentially infested whitebark pine stands. Stand susceptibility to mountain pine beetle infestation may be identified from density (basal area) or relative density (SDI) thresholds. Predictor variables selected by the models corroborate the susceptible host characteristics identified in other mountain pine beetle–pine systems. This work presents evidence of the generality of host susceptibility characteristics across pine species and over elevation gradients. Perkins and Roberts et al. 2003. For. Ecol. Manage. 174: 495-510.


Author Keywords

Whitebark pine; Mountain pine beetle; Host susceptibility; Logistic regression; Generalized linear models














A GIS-supported model for the simulation of the spatial structure of wildland fire, Cass Basin, New Zealand

George .L.W. Perry

Department of Geography and Environmental Studies, The University of Melbourne, Parkville, VIC 3052, Australia

Ashley .D. Sparrow, Ian .F. Owens

Department of Plant and Microbial Sciences, University of Canterbury, Private Bag 4800, Christchurch, New Zealand

1. The behaviour of wildland fire in spatially heterogeneous landscapes was simulated using a model (PYROCART) that integrates the Rothermel fire spread model and a geographic information system (GIS).
2. The principal aims of the research were to test the applicability of overseas fire behaviour models to New Zealand ecosystems, and to assess the applicability of GIS to fire spread prediction.
3. The model was validated using an uncontrolled fire that occurred in the Cass Basin, South Island, New Zealand in May 1995. This fire burnt 580 ha across a complex vegetation mosaic comprising shrubland, stands of Nothofagus solandri var. cliffortioides, bog and tussockland.
4. The overall predictive accuracy of the model was estimated to be 80%. Prediction accuracies within different fuel types and slope angles are also presented. Fuel type and slope appeared to be the dominant influences on fire spread. No trends in prediction accuracy by wind speed or direction were apparent. The predicted burnt area and the real burnt area had a similar overall shape. It was found, however, that at high wind speeds the model tended to over-predict rates of fire spread in some directions.
5. The PYROCART model shows potential as a land management tool, especially for the testing of hypotheses concerning land management strategies. However, due to the complex input data and parameterization techniques it requires, it is less suitable for in situ fire management. Perry and Sparrow et al. 1999. J. Appl. Ecol. 36: 502-518.


Fire dynamics; fire modelling; geographical information systems; Rothermel model; spatial modelling














Toward error analysis of large-scale forest carbon budgets

  Donald L. Phillips

U.S. Environmental Protection Agency, National Health and Environmental Effects Research Laboratory, 200 SW 35th Street, Corvallis, OR 97333, U.S.A

Sandra L. Brown

Winrock International, 1611 N. Kent Street, Suite 600, Arlington, VA 22209, U.S.A

Paul E. Schroeder

Dynamac Corporation, 200 SW 35th Street, Corvallis, OR 97333, U.S.A.

Richard A. Birdsey

USDA Forest Service, North-east Forest Experiment Station, 100 Matsonford Road, Radnor, PA 19087, U.S.A



Quantification of forest carbon sources and sinks is an important part of national inventories of net greenhouse gas emissions. Several such forest carbon budgets have been constructed, but little effort has been made to analyse the sources of error and how these errors propagate to determine the overall uncertainty of projected carbon fluxes. We performed an error analysis for estimates of tree volume and volume change determined by repeated measurements of permanent sample plots for the South-eastern United States as a step toward assessing errors in the carbon budget constructed by the USDA Forest Service. Error components recognized were: sampling error for sample plot selection; measurement error for tree height and diameter; and regression error for tree volume. Most of the propagated error in volume and volume change estimation was due to sampling error. Error estimates depended on the size of the area examined (single state to region) and the degree to which tree growth and recruitment balanced mortality and harvesting. Approximate regional 95% confidence intervals were 3 455 073 000 ± 39 606 000 (1.1%) m3 for current growing-stock volume, and 10 616 000 ± 4210 000 (39.7%) m3 years–1 for growing-stock volume change. These methods should be useful in further analysis of the sources of error and overall uncertainty in national efforts to quantify carbon fluxes associated with forests and land cover dynamics. Phillips and Brown 2000. Global Ecol. Biogeogr.  9: 305–313.


Key words

Carbon budget, carbon flux, error analysis, forest, forest inventory, South-eastern USA, wood volume.















Crown and stand characteristics of Eucalyptus nitens in response to initial spacing: implications for thinning

E. A. Pinkard, W. A. Neilsen
Forestry Tasmania, 79 Melville Street, Hobart, Tasmania 7000, Australia


An experiment was established in a 7-year-old Eucalyptus nitens (Deane and Maiden) Maiden spacing trial, to investigate the effects of initial spacing on crown and stand characteristics. Stocking varied between 500 and 1667 stems per hectare (SPH). Trees from the highest and lowest stocking treatments were harvested to look at aboveground biomass production, biomass partitioning, functional relationships between crown components, individual tree versus stand production and leaf area index. It was found that the lower initial stocking did not affect total aboveground biomass per tree, but increased biomass partitioning to the stem at the expense of branches. Hence stem volume per tree was substantially greater at the lower stocking level. This was a result of greater diameter at breast height (DBH) but not height growth. Trees grown at the lower stocking had greater leaf area per tree, although the relationship between leaf area and sapwood cross-sectional area was not affected by stocking. The only functional relationships that were affected by stocking were those of cross-sectional area and stem volume, tree height, branch dry mass or stem dry mass. Stocking affected these because of changes in stem shape and taper or partitioning to branches. At a stand level total biomass and volume increased with increasing stocking but individual tree size decreased. The relationship between leaf area index and spacing was curvilinear, with no significant differences between stockings above 833 SPH. The results are discussed in terms of the optimal initial spacing and implications for mid-rotation thinning. Pinkard and Neilsen2003. For. Ecol. Manage. 172: 215-227.


Author Keywords

Stocking; Allometrics; Biomass partitioning















Elements of a certification system for forestry-based carbon offset projects



Pedro Moura Costa

EcoSecurities Ltd UK, 45 Raleigh Park Road, Oxford, OX2 9AZ, UK

Marc Stuart

EcoSecurities Ltd. US, Harvard Square, 206 W. Bonita, Claremont, CA 91711, US

Michelle Pinard

Department of Forestry, University of Aberdeen, AB24 5UA UK

Gareth Phillips

SGS YICS, SGS House, Wellheads Drive, Aberdeen AB21 7GQ, UK


Implementation of the Kyoto Protocol will require the establishment of procedures for monitoring, verification and certification of carbon offset projects. In this paper, the steps required for independent certification of forestry-based carbon offset projects are reviewed, based on the procedures used by the international certification company Société Générale de Surveillance. Firstly, a project must be evaluated for its suitability in relation to eligibility criteria of the Kyoto Protocol. These eligibility criteria are classified under four headings: (a) acceptability to host country parties and international agreements; (b) additionality, in terms of demonstrated positive greenhouse gas effects additional to the "businessas-usual" case; (c) externalities or unwanted side effects; and, (d) capacity to implement project’s activities. Secondly, the scientific methodology for calculating the carbon offsets and the methodology for data collection and statistical analysis must be evaluated. Additionally, the amount of carbon offsets quantified must be adjusted to reflect the uncertainty associated with the methodology and data used. Only when these steps have been completed can carbon offsets be certified. Finally, the paper discusses the importance of standardization of methods and procedures used for project monitoring and verification, and the need for accreditation to ensure that the activities of certifiers are regulated. Costa and Stuart et al. 2000. Mitigation and Adaptation Strategies for Global Change, 2000


Carbon sequestration, sinks, verification, certification, baselines, additionality, risk















Thinning Response and Thinning Bias in a Young Scots Pine Stand


Timo Pukkala

University of Joensuu, Faculty of Forestry, P.O. Box 111, FIN-80101 Joensuu, Finland

Jari Miina

Finnish Forest Research Institute, Joensuu Research Centre, P.O. Box 68, FIN-80101 Joensuu, Finland

Marc Palahí

European Forest Institute, Torikatu 34, FIN-80100 Joensuu, Finland




The study analyses the annual post-thinning response and thinning bias of a young Scots pine stand as a function of tree size, competition faced by the tree, and competition that is removed around the tree in the thinning treatment. The thinning response of a tree was defi ned as the change of tree growth due to a thinning treatment. The thinning bias was defined as the difference between the true growth and model prediction. A distance-dependent (spatial) and a distance-independent (non-spatial) growth model were used in the calculations. The empirical data were measured from a thinning experiment consisting of ten plots, each 40 × 30 m in size, which were thinned to different stand densities. The ten-year post-thinning growth of every remaining tree was measured. The results indicated that the highest thinning response is among medium-sized and co-dominant trees. The thinning response is quite small, and even negative for some trees, for two years after thinning but it becomes clearly positive from the third year onwards. The spatial model underestimated the growth of small trees (which usually face high competition) while the non-spatial model overestimated the growth of trees that are small or face much competition. The spatial model used in this study overemphasized the effect of competition while the non-spatial model underestimated this effect. Both growth models overestimated the growth of trees in heavily thinned places, but this bias disappeared in two years. The negative bias was more pronounced with a spatial growth model because the tendency of the non-spatial model to underestimate the growth of trees facing little competition partly compensated for the negative bias. Pukkala and Miina et al. 2002. Silva Fenn. 36: 827-840.



growth model, non-spatial model, spatial model, Pinus sylvestris
















A Bayesian Approach to Nonlinear Random Effects Models



A. Racine-Poon

Mathematical Applications, CIBA-GEIGY AG, CH-4002 Basel, Switzerland



Nonlinear random effects models are considered from the Bayesian point of view. The method of analysis follows closely that of Lindley and Smith (1972, Journal of the Royal Statistical Society, Series B 34, 1-42). The numerical method is related to the EM algorithm. Racine-Poon 1985.Biometrics 41: 1015-1023.














Tree biomass in the North Central Region

Gerhard K. Raile, Pamela J. Jakes

North Central Forest Experiment Station Forest Service-US department of  Agriculture 1992 Folwell Avenue, St. Paul, Minnesota 55108



Methods for calculating tree biomass are outlined, and the biomass on commercial forest land is estimated for 11 north-central states. Tree biomass in the North Central Region totals 3.6 billion tons, or 50 tons per commercial forest acre. For all species, total tree biomass is concentrated in growing-stock boles. Raile and Jakes 1981. Research Paper NC-220. St. Paul, MN: U.S. Dept. of Agriculture, Forest Service, North Central Forest Experiment Station 1982.


Key Words

Tree weight, tops and limbs, energy













SAFIS Area Estimation Techniques


Gregory A. Reams

Southern Research Station, Forest Inventory and Analysis Program, USDA Forest Service.



The Southern Annual Forest inventory System (SAFIS) is in various stages of implementation in 8 of the 13 southern states served by the Southern Research Station of the USDA Forest Service. Compared to periodic inventories, SAFIS requires more rapid generation of land use and land cover maps. The current photo system for phase one area estimation has changed little over the last four decades and provides area estimates within the precision requirements of the FIA program. A stated goal of the national FIA program is to eventually replace photo interpretation with digital satellite classiflcation because the photo system cannot produce maps of forest and nonforest area, and it takes an enormous amount of time to photo interpret the phase one photo plots. Using automated classification procedures for TM satellite data, we anticipate that the time to complete phase one will decline and wall-to-wall maps will be available. In the interim period of switching to satellite data, the photo system must be modified to provide current estimates of inventory. A method -being used by Southern FIA is documented.  

































An Assessment of First and Second Rotations Average Dominant/Codominant Height Growth for Slash Pine Plantations in South Georgia and North Florida


Charles E. Rose, Jr.,Barry D. Shiver

Daniel B. Warnell School of Forest Resources, The University of Georgia, Athens, Georgia 30602-2152



A slash pine (Pinus elliottii Engelm.) successive rotation plantation study was established in 1978–1979 for the north Florida and south Georgia flatwoods. The second rotation duplicated the first rotation seed source, site preparation, planting method and density. The comparison between the two rotations is based on the mean dominant/codominant height differential across a range of soil types and ages. There is a significant rotation 1 minus rotation 2 mean dominant/codominant height difference across the sites for all ages. Rotation 1 is 1.9 and 5.4 ft higher for mean dominant/codominant height at ages 2 and 20. The height differential is generally more significant for the spodosol soil type than the nonspodosol soil type. Rotation 1 generally experienced more favorable precipitation, for both the amount and timing of the precipitation within a year, than rotation 2. Rotation 2 experienced drought events and high growing season average temperatures during the first two growing seasons, while rotation 1 was near normal for this period. The evidence suggests that a main contributor to the decrease in mean dominant/codominant height across the spectrum of plots and age classes is the generally less favorable climatic growing season conditions experienced by rotation 2 relative to rotation 1. Rose and Shiver 2002. South. J. Appl. For. 26(2): 61–71.


Key Words

Slash pine, successive rotations, mean dominant/codominant height, precipitation.















Growth response of longleaf pine (Pinus palustris Mill.) seedlings to fertilization and herbaceous weed control in an old field in southern USA

Craig L. Ramsey, Shibu Jose

School of Forest Resources and Conservation, 5988 Hwy 90, Building 4900, University of Florida, Milton, FL 32583, USA

Barry J. Brecke

b West Florida Research and Education Center, 4253 Experiment Road, Jay, FL 32565, USA

Sara Merritt
 School of Forest Resources and Conservation, 5988 Hwy 90, Building 4900, University of Florida, Milton, FL 32583, USA


The resurgence of longleaf pine (Pinus palustris Mill.) planting in the past decade has fueled the need for better understanding of the adaptation of current silvicultural practices to pine species better. Use of herbicides and fertilizer to accelerate the emergence of longleaf pine seedlings out-of-the-grass stage has rapidly started to replace prescribed fire as the preferred management practice in plantations. The objective of this study was to measure the effects and interaction of weed control and fertilization on longleaf seedling growth and survival. A 2×2 factorial study, installed as a randomized complete block design was conducted over two growing seasons in Santa Rosa County, FL. Hexazinone (0.74 kg a.i. ha-1) and Sulfometuron methyl (0.16 kg a.i. ha-1) were applied on an annual basis, while fertilizer (10-10-10) was applied at the rate of 560 kg ha-1, 5 months after planting. Except for survival, the effects of fertilizer and weed control were not additive by the end of the second growing season. Longleaf pine survival was highest for the weed control (84%) and lowest for the fertilizer (53%) treatments. This pattern was repeated for root collar diameter (RCD) and height growth. Seedling height for weed control and control treatments were 33.4 and 13.4 cm, respectively, at the end of the second growing season. Regression analysis revealed that longleaf emergence from the grass stage was not dependent on an RCD threshold, but on the degree of neighboring competition. Herbaceous weed control during the early establishment phase appears to be critical in accelerating height growth of longleaf pine seedlings in old fields. Ramsey and Jose et al. 2003. For. Ecol. Manage. 172: 281-289.


Author Keywords

Longleaf pine (Pinus palustris); Grass stage; Herbaceous weed control; Herbicides; Hexazinone; Sulfometuron methyl; Fertilizers; Old field














Models of potential height and diameter for Eucalyptus globulus in Portugal

D. D. Reed

School of Forestry and Wood Products, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA

E. A. Jones

Department of Mathematical Sciences, Michigan Technological University, 1400 Townsend Drive, Houghton, MI 49931, USA

M. Tomé

Departmento de Engenharia Florestal, Instituto Superior de Agronomia, Universidade Técnica de Lisboa, Tapada da Ajuda, 1399, Lisboa Codex, Portugal

M. C. Araújo

CELBI, Quinta do Furadouro, Amoreira (Oeste), 2510, Obidos, Portugal


When modeling tree dimensions, it is common in many forest growth models to first predict the potential diameter or height in the absence of resource limitation, and then to modify this downward using functions reflecting the impact of various limiting resources on growth. Most of these models, however, were not parameterized using observations of true potential growth. This study utilizes data from a field trial of Eucalyptus globulus in central Portugal to parameterize models of potential height and diameter of E. globulus in the absence of growth reduction due to moisture or nutrient limitation. The resulting models represent tree height and diameter as functions of a single variable, the growing degree days (5 °C basis) accumulated since the date of planting. Reed and Jones et al. 2003. For. Ecol. Manage. 172: 191-198.


Author Keywords

Eucalyptus globulus; Forest growth models; Potential growth; Growing degree days















Fragmentation of Continental United States Forests


Kurt H. Riitters

Southern Research Station, US Forest Service, 3041 Cornwallis Road, Research Triangle Park, North Carolina 27709, USA

James D. Wickham

Environmental Sciences Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA

Robert V. O’Neill

O’Neill Consulting, 53 Outer Drive, Oak Ridge, Tennessee 37830, USA

K. Bruce Jones

Environmental Sciences Division, US Environmental Protection Agency, Las Vegas, Nevada 89119, USA

Elizabeth R. Smith

Environmental Sciences Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA

John W. Coulston

Department of Forestry, North Carolina State University, Raleigh, North Carolina 27695, USA

Timothy G. Wade, Jonathan H. Smith

Environmental Sciences Division, US Environmental Protection Agency, Research Triangle Park, North Carolina 27711, USA





We report a multiple-scale analysis of forest fragmentation based on 30-m (0.09 ha pixel_1) landcover maps for the conterminous United States. Each 0.09-ha unit of forest was classified according to fragmentation indexes measured within the surrounding landscape, for five landscape sizes including 2.25, 7.29, 65.61, 590.49, and 5314.41 ha. Most forest is found in fragmented landscapes. With 65.61-ha landscapes, for example, only 9.9% of all forest was contained in a fully forested landscape, and only 46.9% was in a landscape that was more than 90% forested. Overall, 43.5% of forest was located within 90 m of forest edge and 61.8% of forest was located within 150 m of forest edge. Nevertheless, where forest existed, it was usually dominant—at least 72.9% of all forest was in landscapes that were at least 60% forested for all landscape sizes. Small (less than 7.29 ha) perforations in otherwise continuous forest cover accounted for about half of the fragmentation. These results suggest that forests are connected over large regions, but fragmentation is so pervasive that edge effects potentially influence ecological processes on most forested lands. Riitters  and  Wickham et al. 2002. 5: 815–822  


Key words

Forest ecology; edge effect; spatial pattern; landscape pattern; forest fragmentation
















Forest/Nonforest Classification of Landsat TM Data For Annual Inventory Phase One Stratification


Jim Rack

MN Department of Natural Resources, Division of Forestry—Resource Assessment, 413 SE 13th Street, Grand Rapids, MN 55744.



Launch of Landsat 7 creates the opportunity to use relatively inexpensive and regularly acquired land cover data as an alternative to high altitude aerial photography. Creating a forest/nonforest mask from satellite imagery may offer a cost-effective alternative to interpretation of aerial photography for Phase One stratification of annual inventory plots. This paper describes the procedures: they include image rectification, registration, and spatial filtering to allow accurate co-location with field plots and attempt to compensate for minor plot location errors. Identification of clouds and their removal from further analysis is outlined. Image alarms are described as a coarse filter for arriving at a forest/nonforest mask, with unsupervised classification as the fine filter. Accuracy assessment results for single-date, dual-date, filtered and unfiltered combinations are reported, as well as cost estimates. Rack 2000. Paper presented at the Second Annual Forest Inventory and Anaylsis (FIA) Symposium, Salt Lake City, UT, October 17–18, 2000.














Guided Transect Sampling with a New Strategy for Second-Stage Guidance  

Anna Ringvall

Natural Resource Inventory at the Swedish University of Agricultural Sciences, Department of Forest Resource Management and Geomatics, S–901 83 Umeå, Sweden  


Guided transect sampling (GTS) was recently proposed as a method for surveying sparse and geographically scattered populations if prior information with high spatial resolution is available. With this method, wide survey strips are, during a first stage, randomly selected in the area to be surveyed. In the second stage, the selected first-stage strips are subsampled with a survey line or survey strip based on the prior information. In this article, a new strategy for second-stage guidance is developed and evaluated in a simulation study. The suggested strategy uses an assumed model for the relationship between the prior information and the variable of interest to find an efficient design for selecting the secondstage transects. The performance of the suggested strategy is evaluated in terms of the variance obtained in different realizations of the assumed model. Results from the simulation study indicate that the suggested strategy is an efficient alternative to previously suggested strategies, if the correspondence between the model population and the real population is good. On the other hand, if the difference between the two populations is large, large variances were sometimes obtained. Ringvall 2003. For. Sci. 49(2): 169–175.


Key Words

Optimal design, simulated annealing, sparse population, strip survey, two-stage design















Criteria for comparing the adaptability of forest growth models

Andrew P. Robinson

Department of Forest Resources, College of Forestry, Wildlife and Range Sciences, University of Idaho, Moscow, ID 83843, USA
Robert A. Monserud
USDA Forest Service, Pacific Northwest and Rocky Mountain Research Stations, P.O. Box 3890, Portland, OR 97208, USA


We develop criteria that assess the adaptability of forest growth simulation models for extension into new populations and applications. The most important criteria summarize the infrastructure of the model: portability, extendibility, source code availability, and adequate documentation. We apply these criteria to a suite of stand growth models for simulation of a wide range of management alternatives in the Pacific Northwest. None of the candidate models is fully adaptable, but the Forest Vegetation Simulator (FVS) came closest. Robinson and Monserud 2003. For. Ecol. Manage. 172: 53-67


Author Keywords

Model comparison; Criteria; Adaptability; Forest growth models; Pacific Northwest














Analytical Alternatives for an Annual Inventory System


Francis A. Roesch, Gregroy A. Reams

Remote Sensing and Statistical Techniques, USDA Forest Service, Southern Research Station, 160A Zillicoa Street, PO Box 2750, Asheville, NC 28802




Methods for analyzing data from the Southern Annual Forest Inventory System (SAFIS) are discussed. Differences between the annual inventory approach and the more traditional periodic approach require that we revisit the previous assumption that there are no important spatial and temporal trends in the data. Over the next few years, the USDA Forest Service Southern Research Station will be evaluating models of varying complexity to determine the most efficient estimation approach for each variable, at all spatiotemporal scales of interest. Roesch and Reams 1999. J. For. 97: 33-37.


















Ecological Subregion Codes by County, Coterminous United States


Victor A. Rudis

Forest Inventory and Analysis Research Work Unit, Southern Research Station, U.S. Department of Agriculture, Forest Service, Starkville, MS 39760–0928.




This publication presents the National Hierarchical Framework of Ecological Units (ECOMAP 1993) by county for the coterminous United States. Assignment of the framework to individual counties is based on the predominant area by province and section to facilitate integration of county-referenced information with areas of uniform ecological potential. Included are maps illustrating county-scaled ecological subregion boundaries by division, province, and section; and numeric codes by Federal Information Processing Standard and USDA Forest Service Resources Planning Act region. Rudis 2000. A Technical Document Supporting the 2000 USDA Forest Service RPA Assessment.



County, ecological potential, ecological subregion, ecoregion, forest resources, province












Aspen age structure in the northern Yellowstone ecosystem: USA

Eric J. Larsen

Department of Geography and Geology, University of Wisconsin–Stevens Point, Stevens Point, WI 54481-3897, USA

William J. Ripple
Department of Forest Resources, Oregon State University, 280 Peavy Hall, Corvallis, OR 97331, USA


Age-structure analysis of aspen (Populus tremuloides) was conducted on Rocky Mountain elk (Cervus elaphus) winter range in the northern Yellowstone area by collecting increment cores from aspen trees in Yellowstone National Park, the Gallatin National Forest, and the Sunlight/Crandall area of the Shoshone National Forest. Our goal was to compare aspen age structure for elk winter range in the park with age structures developed for elk winter range in the national forests. We collected increment cores from aspen in three diameter size classes and three aspen habitat types (xeric, mesic, and scree). A special effort was made to collect increment cores from the relatively rare scree habitat type, since scree forms a "natural exclosure" where browsing pressure on aspen is reduced. The age structure of aspen in Yellowstone was significantly different from the age structures of aspen in either of the national forest areas (P<0.001). The Gallatin and Sunlight/Crandall age structures were not significantly different (P=0.288). Only 6% of aspen stands in Yellowstone contained stems that originated from 1920 to 1989, while 87 and 84% of the stands in the Gallatin and Sunlight/Crandall areas, respectively, contained stems from that period. Within Yellowstone, the age structure of aspen in the scree habitat type differed significantly from the mesic and xeric sites that were available for browsing (P<0.001). Aspen stems originating after 1920 dominated the scree stands, while trees originating between 1870 and 1920 dominated the non-scree stands. Aspen stands have successfully recruited new stems into their overstories in all habitat types from 1880 to 1989 in elk winter range on national forest areas surrounding the park. Within the park, aspen stands recruited new overstory stems between 1860 and 1929 in all habitat types. Since 1930, Yellowstone aspen have recruited overstory stems mostly in scree habitat type stands and other areas of reduced browsing pressure. We concluded that changes in ungulate browsing patterns due to differences in predation risk best explain the spatial and temporal pattern observed. Larsen and Ripple 2003. For. Ecol. Manage. 179: 469-482.


Author Keywords

Increment core; Elk winter range; Ungulates; Populus tremuloides; Yellowstone National Park

















How well can we select undamaged site trees for estimating site index?

Gordon D. Nigh

British Columbia Ministry of Forests, Research Branch, P.O. Box 9519,Stn Prov Gov, Victoria, BC V8W 9C2, Canada

Bobby A. Love

British Columbia Ministry of Forests, Prince Rupert Forest Region, Bag 5000, 3726 Alfred Avenue, Smithers, BC V0J 2N0, Canada

The best estimates of site index, an indicator of site productivity, are obtained from site trees. Undamaged site trees should be sampled to obtain unbiased estimates of site index. Two juvenile height growth modelling projects provided us with sufficient data to assess our ability to select undamaged lodgepole pine (Pinus contorta var. latifolia Dougl.) and white spruce (Picea glauca (Moench) Voss) site trees. The sample trees were split open to measure height growth from the terminal bud scars. Splitting the stems also revealed damage that was not visible from the outside of the tree. Over 50% of the lodgepole pine trees and 75% of the white spruce trees had damage, which was much higher than expected. Possible causes of damage are frost and insects. The damage does not significantly reduce the height of the spruce trees, but there is evidence that the heights of the lodgepole pine trees are reduced. Nigh and Love 1999. Can. J. For. Res. 29: 1989-1992.


Key Words Plus
Height-growth, curves


















Testing models of unthinned red pine plantation dynamics using a modified Bakuzis matrix of stand properties

Rolfe A. Leary
USDA Forest Service, North Central Forest Experiment Station, 1992 Folwell Avenue, St. Paul Minnesota 55108 USA


The comprehensive graphical matrix of even-aged stand property inter-dependence, first developed by E.V. Bakuzis, facilitates identification and understanding of the relationship among stand properties. Bakuzis' original matrix of eight stand properties, contained 64 cells, was symmetric, but only about 11 of the 64 relationships had shown enough regularity among species to have been named. In this paper I simplify the Bakuzis matrix by reordering the rows and columns to make a more compact, lower triangular arrangement of eight rules or law-like relationships. I then demonstrate matrix use by looking for structural flaws in two models of unthinned red pine (Pinus resinosa) plantation dynamics in the Lake States (Minnesota, Wisconsin, and Michigan) (STEMS and REDPINE), and one from Ontario (yield tables from Petawawa). Flaws were found in each source of projections. REDPINE violates the Sukachev effect, predicts trees will have larger diameters on poor sites than on good sites, and that site has a significant effect on the mean height-stem frequency relation All bi-variate relations for the Petawawa data are identical, which violates several rules. The REDPINE program does the poorest job of the three methods of predicting unthinned red pine plantation stand development, primarily because site index has very little effect on any of the stand variables. Leary  1997. Ecol. Model. 98: 35-46.
















Modeling stem profiles for Pinus densiflora in Korea

Woo-Kyun Lee

Division of Environmental Science and Ecological Engineering, Korea University, Anam-Dong 5Ga, Sungbuk-Ku, Seoul 136-701, South Korea

Jeong-Ho Seo

Institut fuer Forsteinrichtung und Ertragskunde, Buesgenweg 5, Goettingen 37077, Germany

Young-Mo Son, Kyeong-Hak Lee

Korea Forestry Research Institute, Cheongryangri-Dong, Dongdaemun-Ku, Seoul 136-012, South Korea

Klaus von Gadow
Institut fuer Forsteinrichtung und Ertragskunde, Buesgenweg 5, Goettingen 37077, Germany



A new taper model is presented for Pinus densiflora in Korea. The new variable-exponent model describes well the gradually changing tree form along the stem. The changing exponent of the new model can be used to graphically compare different stem forms among tree groups. And various form indices numerically expressing stem form are derived from the new model. Five form indices: (1) taper rate of the butt section, (2) inflection point, (3) parabolic or paraconic range, (4) minimum exponent, and (5) relative height at the minimum exponent, are useful analytical tools for numerically comparing stem forms and stratifying trees into different form groups. Lee and Seo et al. 2003. For. Ecol. Manage. 172: 69-77.


Author Keywords

Stem taper model; Variable exponent; Stem form index; Inflection point; Parabolic range; Minimum exponent












Stand table modelling through the Weibull distribution and usage of skewness information

S. R. Lindsay, G. R. Wood

Department of Mathematics and Computing, Central Queensland University, Rockhampton Qld. 4702 Australia
R. C. Woollons
School of Forestry, University of Canterbury, Private Bag 4800 Christchurch New Zealand


A very common practice in forest modelling is to summarise diameter distribution data through use of probability density functions. By far the most popular model is the Weibull which, as well as being versatile, has the distinct advantage that its parameters are readily estimable. In practice, the location parameter a is usually equated to a minimum (sample) value. The scale and shape parameters are estimated iteratively or (approximately) explicitly, through use of moments or percentiles. Here, we expand and develop the use of moments to estimate all three parameters; the essential enhancement is that information concerning the distribution asymmetry is utilised, via the sample skewness statistic. Normally, this information is ignored. Applying the methodology to a Pinus radiata dataset showed that the goodness of fit was improved on average by 15%. On modern computers the method is easily and quickly assayed, so its usage is recommended. There are grounds for suggesting that the method could be embedded in diameter distribution growth-and-yield systems to good effect. Lindsay and Wood et al. 1999. For. Ecol. Manage. 81: 19-23.


Author Keywords

Diameter distribution prediction; Method of moments estimation; Skewness information


















Individual-tree growth and mortality models for Eucalyptus grandis (Hill) Maiden plantations in Zimbabwe

Danaza Mabvurira
Plantations Silviculture Research, Zimbabwe College of Forestry, Box 660, Mutare, Zimbabwe
Jari Miina
Faculty of Forestry, University of Joensuu, P.O. Box 111, FIN 80101 Joensuu, Finland


A distance-independent diameter growth model and a static height model for Eucalyptus grandis in Zimbabwe were developed from spacing experiments designed as Nelder wheels and randomised complete blocks (RCB). The experiments were replicated on five different sites, which ranged in site index (at an index age of 7 years) from 14 to 37 m. Models for the self-thinning limit and probability of a tree dying were fitted to account for mortality. Also, a distance-dependent diameter growth model was fitted to the data from three sites (site indices 14–26 m). The data consisted of about 2000 and 8000 observations for spatial and non-spatial diameter growth models, respectively, and ranged in age from 2.2 to 8.3 years for the spatial growth model, and from 1.3 to 14.6 years for the non-spatial model. The total residual variation increased by 2.3% only, while the adjusted R2 value decreased from 0.31 to 0.29, when the spatial competition index was excluded from the model. The models provided fairly accurate predictions of stand volume in normally stocked stands on moderately fertile to fertile sites (site indices 19 and 26). The models can be used, e.g. in a simulation–optimisation system to determine optimal management regimes for E. grandis in Zimbabwe. Mabvurira and Miina 2002. For. Ecol. Manage. 161; 231:245.

Author Keywords

Growth and yield; Spatial model; Mixed models; Spacing trials; Nelder design


















Derivation of stem taper from the pipe theory in a carbon balance Framework

 Annikki Mäkelä

Department of Forest Ecology, University of Helsinki, P.O. Box 27 (Latokartanonkaari 7), FIN-00014 University of Helsinki, Finland




A dynamic tree growth model is described. The model derives the development of stem taper and vertical distribution of branch basal area from the pipe model, assuming that reuse of active pipes is regulated by foliage dynamics in a vertically explicit crown with a foliage distribution of constant shape. Based on empirical findings, the pipe model was modified slightly to allow the foliage/sapwood ratio to vary as a function of distance from the treetop. Growth was derived from carbon balance in a stand of different size trees that may shade each other. The model was applied to old and middle-aged trees growing in dense and sparse stands of Scots pine for which stand-level measurements are available as a chronosequence, but individual trees have been measured only once. Measured trees were compared with corresponding simulated trees for stem taper and vertical distribution of branch basal area. The results indicated that the pipe model assumptions, combined with a model of tree growth, are capable of producing realistic predictions of the vertical distribution of stem and branch diameter in trees of different sizes in the stand. A comparison of the results with a simple form of the uniform stress theory showed good agreement between the two models. However, a significant difference was found between the measured relative contribution of heartwood to total stem diameter and the predicted share of disused pipes in the stem. A possible explanation for this discrepancy is that the transition from sapwood to heartwood is gradual rather than abrupt as assumed in the model. Amodification of the pipe model to incorporate a gradual transition is outlined. Makela 2002. Tree Physiol. 22, 891–905.



Active pipes, disused pipes, growth model, heartwood, profile theory, sapwood, uniform stress theory, wood quality.
















Predicting basal area of Scots pine branches

Harri Mäkinen

Finnish Forest Research Institute, Vantaa Research Centre, P.O. Box 18, FIN-01301, Vantaa, Finland
Annikki Mäkelä
Department of Forest Ecology, University of Helsinki, P.O. Box 24, FIN-00014 University of, Helsinki, Finland


The aim of this study was to assess and to develop models for the variation of basal area of branches in Scots pine at different heights within the live crown. The models had to be applicable as submodels in growth simulators in order to predict the effects of silvicultural treatments on wood quality. Models were developed for predicting the basal area of the largest and smallest live branch in a whorl (method I), relative basal area distribution on the basis of the thickest branch (method II), and basal area of branches and its variance (method III). Random variation of the dependent variables was divided into variance components at the stand, plot, tree, whorl and branch level. Furthermore, the mutual correlation of the dependent variables in the different models was taken into account by using multivariate models. Method I predicted the basal areas of the largest and smallest branch unbiased when the total basal area of branches and number of live branches in each whorl were known. Because methods II and III do not require that the total basal area of branches be predicted with other models, they can be applied more generally. However, methods based on total or mean basal area of branches (methods I and III) were more accurate than models relying on basal area of the largest branches (method II). Even though there was bias in predicting some branch properties, the behaviour of the models was logical and they provide a framework for predicting basal areas of branches within the live crown on the basis of routine stand and tree measurements. Makinen and Makela 2003. For. Ecol. Manage. 179: 351-362.


Author Keywords

Branchiness; Pinus sylvestris; Wood quality; Variation in branch properties


















Comparison of percentile based prediction methods and the Weibull distribution in describing the diameter distribution of heterogeneous Scots pine stands

Matti Maltamo

Finnish Forest Research Institute, Joensuu Research Station, PO Box 68, FIN-80101 Joensuu, Finland

Annika Kangas

Finnish Forest Research Institute, Kannus Research Station, PO Box 44, FIN-69101 Kannus, Finland

Janne Uuttera

University of Joensuu, Faculty of Forestry, PO Box 111, FIN-80101 Joensuu, Finland

Tatu Torniainen

Forst project c/o Tanzania Forestry Research Institute, PO Box 1854, Morogoro, Tanzania
Jussi Saramäki
University of Joensuu, Faculty of Forestry, PO Box 111, FIN-80101 Joensuu, Finland


The goal of this study was to compare percentile based distribution methods and the Weibull distribution method in predicting the stand characteristics of forests with great variability in their diameter distribution. Stand structure characteristics were compared between thinned and unthinned stands dominated by Scots pine. The thinned forests were located in eastern Finland, while the unthinned natural forests were located in Republic of Karelia and Leningrad district, Russian Federation. Each data sets included 49 stands.


The diameter distributions were more heterogeneous in the unthinned stands. Most of the thinned stands formed unimodal distributions. Among the unthinned stands, decreasing, multi-modal and irregular forms of diameter distributions were also found. In these data, percentile based distribution methods proved to be considerably more effective in predicting the diameter distribution than the Weibull distribution method. With the percentile based distribution method it was also possible to reproduce considerably varying shapes of diameter distributions. Maltamo and Kangas et al. 2000. For. Ecol. Manage. 133: 263-274.


Author Keywords

Diameter distribution prediction; Forest management; Stand structure


















Methods based on k-nearest neighbor regression in the prediction of basal area diameter distribution

Matti Maltamo

Finnish Forest Research Institute, Joensuu Research Station, PO Box 68, FIN-80101 Joensuu, Finland

Annika Kangas

Finnish Forest Research Institute, Kannus Research Station, PO Box 44, FIN-69101 Kannus, Finland

In the Finnish compartmentwise inventory systems, growing stock is described with means and sums of tree characteristics, such as mean height and basal area, by tree species. In the calculations, growing stock is described in a treewise manner using a diameter distribution predicted from stand variables. The treewise description is needed for several reasons, e.g., for predicting log volumes or stand growth and for analyzing the forest structure. In this study, methods for predicting the basal area diameter distribution based on the k-nearest neighbor (k-nn) regression are compared with methods based on parametric distributions. In the k-nn method, the predicted values for interesting variables are obtained as weighted averages of the values of neighboring observations. Using k-nn based methods, the basal area diameter distribution of a stand is predicted with a weighted average of the distributions of k-nearest neighbors. The methods tested in this study include weighted averages of (i) Weibull distributions of k-nearest neighbors, (ii) distributions of k-nearest neighbors smoothed with the kernel method, and (iii) empirical distributions of the k-nearest neighbors. These methods are compared for the accuracy of stand volume estimation, stand structure description, and stand growth prediction. Methods based on the k-nn regression proved to give a more accurate description of the stand than the parametric methods. Maltamo and Kangas 1998. Can. J. For. Res. 28 : 1107-1115.

Key Words Plus
Pinus-sylvestris, picea-abies, stands


















Evaluating forest models in a sustainable forest management context

Robert A. Monserud

PNW Research Station, USDA Forest Service, 620 SW Main St., Suite #400, Portland, Oregon, USA 97205


My objective is to examine the expected utility of general classes of forest growth models for answering questions regarding the sustainability of forest management. Six classes of forest models are reviewed: Forest Yield Models; Ecological Gap Models (population succession); Ecological Compartment Models (resources fluxes); Process/Mechanistic Models; Vegetation Distribution Models; Hybrid Models. The review reveals structural shortcomings in several classes of models as potential tools for evaluating questions of sustainable forest management. For example, the great disadvantage of Forest Yield Models is that they are not linked to the underlying causes of productivity (the carbon and nutrient cycles, the moisture regime, and climate). Yield models implicitly assume that environmental conditions remain constant. This assumption is clearly unsuitable for evaluating climate change scenarios, which are crucial for long-term sustainability considerations. Hybrid models hold the greatest promise, because they are predicated on producing an operational process model with useful products on yield for the manager (e.g., PipeQual, Stand-BGC). The hybrid modelers base as much of their system on causal process models as is practical, and openly embrace relevant empirical results from yield models to complete the system. Monserud 2003. FBMIS 1: 35-47. 


Sustainability, forest yield models; ecological gap models, population succession models, ecological compartment models, resources flux models, process models, mechanistic models, vegetation distribution models, hybrid models.














Results from a thinning experiment in a Scots pine (Pinus sylvestris L.) natural regeneration stand in the Sistema Ibérico Mountain Range (Spain)

G. Montero, I. Cañellas, C. Ortega

Dpto. Selvicultura, CIFOR-INIA, Apdo. 8.111, 28080 Madrid, Spain

M. Del Rio

Dpto. Producción Vegetal y Silvopascicultura. University Valladolid, Avda. de Madrid 57, 34004 Palencia, Spain


In this paper, we present data and results about a thinning experiment in a natural regeneration stand of Pinus sylvestris L. in Burgos (Spain). The stand has a site index of 29 m at the age of 100 years, according to the site curves given by Rojo and Montero [El pino silvestre en la Sierra de Guadarrama. MAPA, Madrid, 1996, p. 293]. The experiment began in 1972, when the stand was 41 years old. It is now 66 years old. The statistical design of the experiment was a randomised complete block with three blocks and three treatments. Low thinning was carried out with varying intensities in a 10-year rotation (1972, 1982, 1992). The treatments were control, light and moderate thinning. The thinning intensity was measured by using the residual basal area (%) as parameter. Since the first inventory (1972) we have made four more.


Effects of these treatments on stand yield, mean tree and stand structure are studied. Results showed that with the heaviest thinning the total yield of the stand was a bit lower than in control treatment. According to these results the heaviest treatment of the trial is near the lower density limit for this species (critical basal area of Assmann). On the other hand, mean tree and stand structure characteristics become more suitable for crop stability increment when thinning were heavier. The greater the intensity of thinning, the lesser the h/d ratio and the larger the square mean diameter too. As conclusion, we recommend low heavy thinning in early ages, reducing the intensity with age. Specially in stands of middle and high quality, the first thinning should be early, at 20–25 years old, despite the lack of economic profit at this stage. Montero and Cañellas et al. 2001. For. Ecol. Manage. 145:151-161.


Author Keywords

Thinnings intensity; Pinus sylvestris; Stand density; production

















Taper equations for Eucalyptus pilularis and Eucalyptus grandis for the north coast in New South Wales, Australia

Charles K. Muhairwe
State Forests of NSW, Locked Bag 23 Pennant Hills, NSW 2120 Australia


Function which predict tree taper are tools that can be used by forest managers to provide accurate and timely information on current growing stock. State Forests of New South Wales has embarked on a program of collection and analysis of data for volume and taper information. Taper models for blackbutt (Eucalyptus pilularis Smith) and flooded gum (E. grandis W. Hill ex Maiden) were fitted using historical data from the northern coastal areas of New South Wales, as part of the program. Two taper models were developed for each species, one using total tree height in addition to diameter at breast height over bark and sectional height and the other using only diameter at breast height over bark and sectional height. The two taper models were compared with well tested taper models by Max and Burkhart (1976), Kozak (1988), and Gordon (1983) taper form. The taper model developed using total height in addition to dbh and sectional height (model 1a) performed best for describing the stem profile and predicting stem volume for blackbutt and flooded gum. The modified Gordon (1983) taper model (model 5b) was the most precise model for flooded gum even though it was biased. Model 1a is recommended for use for blackbutt and model 5b for flooded gum for the north coast of NSW. Muhairwe 1999. For. Ecol. Manage. 113: 251-269.















Stand Volume Functions for Picea abies in Eastern, Central and Northern Norway

Erik Naesset,

Agricultural Uni6ersity of Norway, Department of Forest Sciences, P.O. Box 5044, NO- 1432 Ås, Norway

  Bjorn Tveite

Norwegian Forest Research Institute, HØgskolevn. 12, NO- 1432 Ås, Norway




A material of 615 observations was used to develop Norway spruce (Picea abies (L.) Karst.) stand volume functions for eastern, central and northern Norway. A multiplicative model with three independent variables was found to be most suitable. The independent variables were stand basal area, Lorey's mean height, and site index. The R2 value was 0.993 and the coefficient of variation 5.43%. Testing by means of two independent data sets indicated that the function is suitable for practical prediction purposes for different site qualities and in different geographical regions of the country. Naesset and Tveite 1999. Scand. J. For. Res. 14: 164–174.


















Prediction intervals for estimates of site index based on ecosystem type

Gordon Nigh

Research Branch, British Columbia Ministry of Forests P.O. Box 9519, Stn. Prov. Govt. Victoria, British Columbia Canada V8W 9C2



British Columbia has an ecosystem classification system that classifies sites into site series. Foresters commonly measure the productivity of these sites by their site index. In British Columbia, site index is defined as the height of a stand at breast height age 50 and is usually estimated from height–age models. Biogeoclimatic site series/site index relationships are an increasingly popular method of estimating site index in British Columbia for stands where site index cannot be reliably estimated with height–age models. The precision of the predicted site index from these relationships can be evaluated with prediction intervals. This is done for the predicted site index of a single site, a group of sites, or the areally weighted site index of a group of sites. The methodology is also useful in determining the number of sites required to meet a specified precision. These prediction intervals will assist foresters in making sound forest management decisions. Nigh 1998. Environ. Manage.  22: 197–202

















Modelling the risk of snow damage to forests under short-term snow loading

Marja-Leena Päätalo, Heli Peltola,  Seppo Kellomäki
University of Joensuu, Faculty of Forestry, P.O. Box 11 FIN-80101 Joensuu Finland


Regression models are developed to assess the risk of snow damage to Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst) and birch (Betula spp.) stands based on simulated data, employing a mechanistic wind and snow damage model developed by Peltola et al., 1998a. The risk is predicted in terms of the critical windspeed needed to cause stem breakage and uprooting of trees at forest edges under short-term snow loading. Separate regression models are developed for each tree species using stem taper (breast height diameter of stem relative to tree height, d1.3/h), stand density, snow loading and distance from the stand edge as variables, and a general model for stem breakage and uprooting is also proposed having tree species as an additional dummy variable. The overall risk of stem breakage and uprooting is shown to increase with snow loading and decrease with increasing stem taper and stand density for all three tree species, although Scots pines and Norway spruces are predicted to be much more susceptible to snow damage than birches, which, being leafless, had much less crown area for snow attachment and wind loading. The greatest susceptibility to stem breakage and uprooting is seen at the stand edge, where the risk due to wind loading is much greater than inside the stand. Under these circumstances, slightly tapering Scots pines and Norway spruces are found to be the most vulnerable under a snow load of 60 kg m-2, suffering damage at windspeeds of <9 m s-1 at a constant height of 10 m above the ground, i.e. these windspeeds enhance the risk, whereas higher speeds can be expected to dislodge the snow from the crowns. Birches will only exceptionally be broken and uprooted at windspeeds of <9 m s-1 according to the models developed here. Since the general models give rise to somewhat greater residuals compared with the simulated data than do the single tree species models, it seems that the latter will give more reliable predictions of the risk of snow damage. The models could be useful when discussing the risk of snow damage in connection with alternative forms of stand management, especially in high risk areas, enabling high-risk trees to be removed during thinning. Paatalo and Peltola et al.  1999. For. Ecol. Manage. 116: 51-70.


Author Keywords

Critical snow load; Critical windspeed; Stem breakage; Uprooting; Mechanistic wind and snow damage model; Scots pine; Norway spruce; Birch; Stand management; Risk assessment; Regression models

















Risk of Snow Damage in Unmanaged and Managed Stands of Scots Pine, Norway Spruce and Birch

Marja-Leena Päätalo

Faculty of Forestry, Uni×ersity of Joensuu, P.O. Box 111, FI-80101 Joensuu, Finland



The aim of this study was to assess the risk of snow damage to trees in unmanaged and managed stands of Scots pine (Pinus sylvestris L.), Norway spruce [Picea abies (L.) Karst.] and birch (Betula spp.) over a rotation. The risk assessment was based on the prediction of critical snow loads in interaction with the windspeed at which trees can be expected to break or be uprooted, and on the frequency of long-term extremes of precipitation and of suitable temperature conditions for the accumulation of snow on the tree crowns. The Scots pine stands were found to be more susceptible to snow damage than the others, and an unmanaged stand of Scots pine to be more susceptible to break and uproot than a managed one. Correspondingly, an unmanaged stand of Norway spruce was more susceptible to stem breakage than a managed one, but less susceptible to uprooting. Neither unmanaged nor managed birch stands were likely to suffer any kind of snow damage. The susceptibility of unmanaged stands is caused by low tapering of the trees. Based on the frequency of long-term extremes in precipitation at the temperatures needed for snow accumulation on tree crowns, critical snow loads of 10-19, 20-29 and 30-39 kg m-2 occurred 19.3, 3.3 and 1.3 times in a decade in southern Finland. Critical snow loads of 10-19, 20-29, 30-39 and 60-69 kg m-2 occurred in northern Finland 17.0, 6.3, 1.7 and 0.3 times in a decade. Paatalo 2000. Scand. J. For. Res. 15: 530-541.















Missing growth rings at the trunk base in suppressed balsam fir saplings

Sylvain Parent, Hubert Morin

Département des sciences fondamentales, Université du Québec à Chicoutimi, Chicoutimi, PQ G7H 2B1, Canada
Christian Messier

Universite du  Québec à Montréal, Départment des sciences biologiques, C.P. 8888, Succursale Centre-Ville, Montréeal , QC H3C 3P8, Canada

Numerous researchers have suggested a causal relationship between low leaf biomass in suppressed trees and the lack of radial growth at the base of the trunk. The objective of this study was to verify this relationship with suppressed balsam fir (Abies balsamea (L.) Mill.) saplings found growing in an old-growth fir stand. A total of 29 saplings varying in height from 67 to 183 cm were uprooted. All saplings had adventitious roots. All terminal bud scars (TBS) found between the apex of the terminal leader and the trunk base (first adventitious root) as well as those found below ground were localized, and rings were counted between TBS along the aboveground trunk. Various morphological traits and the ratio of photosynthetic tissue dry mass (P, needles) to non-photosynthetic tissue dry mass (nP, aboveground stem) were used as an indicator of tree vigour. Between 3 and 33 rings counted along the aboveground trunk were missing at the trunk base. The number of missing rings at the base of the trunk was correlated with total height (r = 0.41), height growth (r = -0.51), radial growth (r = -0.44), the P/nP ratio (r = -0.73), and the proportion of live crown (r = -0.62). Moreover, from 2 to 35 additional rings, missing at the trunk base, were found in the belowground section of trunk and these missing rings were associated with the adventitious roots phenomenon. In conclusion, suppressed firs had missing rings at the base of the trunk. When all of the missing rings were added to the number of rings counted at the base of the trunk, age estimates provided a different temporal pattern of recruitment compared with that obtained by solely counting rings at the base of the trunk. Stem analysis on the entire trunk is the best aging method for suppressed balsam fir saplings. Parent and Morin et al. 2002. Can. J. For. Res. 32:1776-1783.


Key Words Plus
Spruce budworm, adventitious roots, age-determination, shade tolerance, boreal forest, dynamics, regeneration, tree, survivorship, population
















Virtual experimentation: conceptual models and hypothesis testing of ecological scenarios

Pablo Parysow, George Gertner
Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana-Champaign, W-503 Turner Hall, 1102 South Goodwin Avenue Urbana, IL 61801 USA


Models intended to describe the mechanisms involved in ecological systems (conceptual models) are being increasingly employed to make predictions, and evaluate the effect of different scenarios. We propose a framework for employing conceptual models in hypothesis testing of ecological scenarios for the case external entities have an additive effect on treatment entities. The use of conceptual models to test the effect of scenarios is referred to as `virtual experimentation'. The rationale of virtual experimentation is compared and contrasted with field experimentation. The analysis of the effect of acidic deposition on the site index of a forest stand is employed to illustrate this methodology. A conceptual forest growth model based on the pipe theory and the self-thinning rule is employed to conduct this analysis. In this virtual experiment we assume that the effect of external entities on treatments is additive. It is argued that this study proposes a valuable method for testing the effect of ecological scenarios employing conceptual models. Parysow and Gertner 1997. Ecol. Model. 98: 59-71.


Author Keywords

Conceptual models; Mechanistic models; Hypothesis testing; Experimentation; Ecological scenarios; Environmental scenarios

















Effects of Thinning Regime on the Wood Properties and Stem Quality of Picea abies

Rolf Pape

Department of Forest Yield Research, Swedish University of Agricultural Sciences, P.O. Box 7008, SE- 750 07 Uppsala, Sweden



Seven thinning trials in stands of Norway spruce (Picea abies (L.) Karst.) planted on highly productive sites in southern Sweden were investigated. Cross-sectional weighted basic density was not affected by a thinning regime characterized by several thinnings from below compared with naturally thinned stands. Heavy thinnings decreased basic density. However, the decrease was moderate compared with those reported in earlier investigations, probably owing to the lower stand density prior to first thinning which affected competition between trees and crown differentiation. Thinning from above resulted in a higher basic density, mainly because trees with decreased growth ring development up until the time of the first thinning were favored. Dry matter production was not decreased any more than volume production by any of the treatments except for the very heavy thinning from below. Generally, thinning decreased the juvenile wood content of the stand. As a consequence of selection, thinning from above will decrease the juvenile wood content more compared with thinning from below, provided that trees reach the same diameter in the final stand. Branch diameter in the lower part of the stem was found to be higher in the naturally thinned stands than in the thinned ones. This appeared to be due exclusively to selection since the live crown probably had already started receding upwards prior to the first thinning. Differences in stem taper between thinning regimes could be attributed to changes in growth allocation and effects of selection between trees. Pape 1999. Scand. J. For. Res.  14: 38 – 50.