Biomass
Expansion Factors for Scots pine (Pinus sylvestris), comparison between
Catalonia and Finland
Aleksi
Lehtonen, Jordi Vayreda
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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.
Abstract
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
Abstract
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 (
p.a.u.),
obtained by correcting the photosynthetically active radiation absorbed by the
forest canopy (
p.a.)
for the effects of soil drought, atmospheric vapour pressure deficits and stand
age. PG is obtained from
p.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
power
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
Abstract
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
Abstract
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.
Abstract
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
Abstract
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
Burton,
J.D.
Alexandria Forestry Center, Southern Forest Experiment Station, Forest
Service-USDA, Pineville, Louisiana
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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.
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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.
Keywords
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
Abstract
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.
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
Abstract
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
Abstract
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
Abstract
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 (
10 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
(
60 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
Abstract
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
Abstract
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
Abstract
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.
Keywords
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
Abstract
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.
Keywords
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
Abstract
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.
Keywords
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
Abstract
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.
Keywords
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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.
Keywords
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
Abstract
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.
Keywords
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
Abstract
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.
Abstract
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
Abstract
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
Abstract
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
FOREST
SCIENCE
45
(4): 573-593 NOV 1999
Abstract
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
Abstract
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
Abstract
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
Abstract
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
0.001)
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
Abstract
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.
Keywords
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
Abstract
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
Abstract
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
Abstract
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
Keywords
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
Abstract
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.
Keywords
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
Abstract
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
Abstract
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.
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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.
Abstract
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
Abstract
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
Abstract
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
Abstract
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.
Abstract
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.
Keywords
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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.
Keywords
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
Abstract
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
Abstract
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
Abstract
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
Robert
A. Monserud
PNW
Research Station, USDA Forest Service, 620 SW Main St., Suite #400, Portland,
Oregon, USA 97205
Abstract
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.
Keywords
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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
Abstract
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.