Phase I Forest Area Estimation Using Landsat TM And Iterative Guided
Spectral Class Rejection: Assessment of Possible Training Data Protocols
John A. Scrivani
Virginia Department of Forestry, 900 Natural Resources Drive,
Charlottesville, VA
Randolph H. Wynne, Christine E. Blinn, Rebecca F. Musy
College of Natural Resources, Virginia Polytechnic Institute and State
University, Blacksburg, VA
Abstract
Two methods of training data collection for
automated image classification were tested in Virginia as part of a larger
effort to develop an objective, repeatable, and low-cost method to provide
forest area classification from satellite imagery. The derived forest area
estimates were compared to estimates derived from a traditional
photo-interpreted, double sample. One method used maplets digitized from
ancillary imagery. Seed pixels, the other approach, used only available ground
plot data and the image to be classified. Both methods of training data
collection resulted in classification accuracy approaching 89 percent, and area
estimation precision surpassing the FIA standard of 3 percent per million acres
of timberland. However, the precision estimate was met in large part from the
additional ground truth data collected supplemental to the national standard
sample frame of one plot per 6,000 ac. The seed pixel approach is recommended
over maplets, because it does not require ancillary imagery and is less costly
in analyst time. Scrivani and Wynne et al. 2000. Paper
presented at the Second Annual Forest and Inventory (FIA) Symposium, Salt Lake
City, UT, October 17–18, 2000.
Modeling
the Effect of Density on the Growth of Loblolly Pine Trees
Mahadev Sharma, Harold E. Burkhart, and Ralph L. Amateis
Department of Forestry, Virginia Polytechnic Institute and State
University, Blacksburg, VA 24061
Abstract
Data
from a set of loblolly pine spacing trials that have reached 16 yr since
establishment were used to evaluate the effect of spacing on loblolly pine tree
growth and stand development. Mean responses for six variables were evaluated:
height, dbh, crown ratio, crown length, crown width, and survival. All response
variables were affected by density, with dbh being the most affected and height
the least affected over the 16 yr period. The rectangularity, or shape, of the
growing space was not a significant factor in the development of any of these
response variables. Models were constructed to characterize the development of
the six response variables extrapolated over typical plantation rotation lengths
of loblolly pine. Sharma and Burkhart et al. 2002. South. J. Appl. For. 26:124–133.
Key
Words
Density
effect, square spacings, diameter, Pinus taeda L
Top
height definition and its effect on site index determination in thinned and
unthinned loblolly pine plantations
Mahadev
Sharma, Ralph L. Amateis, Harold E. Burkhart
Department of Forestry, VPISU, CNR 0324, Blacksburg, VA 24061, USA
Abstract
Seven definitions of stand (top) height: (1) mean
height of dominant and codominant trees at the time of plot measurement, (2)
mean height of dominant and codominant trees that have always been dominant or
codominant over the life of the stand, (3) Lorey mean height, (4) average height
of the 100 thickest trees per hectare at the time of measurement, (5) average
height of the 100 thickest trees per hectare at the time of last measurement,
(6) average height of the 20% thickest trees at the time of plot measurement,
and (7) average height of the 20% thickest trees at each measurement that also
survived to the last measurement were evaluated for use in site index (SI)
determination. Data collected from permanent plots over a 15-year period in
thinned and unthinned loblolly pine plantations were used to make comparisons.
Except for a few cases at certain measurements, all seven definitions of top
height were significantly different from each other.
Site index was predicted based on these definitions
to determine if one definition is superior. Magnitudes of the maximum range of
residuals and the fit statistics indicated that SI estimated using mean height
of dominant and codominant trees that have always been dominant or codominant
over the life of the stand is more precise than site indices estimated using
other definitions. Using this definition of top height, a new SI equation for
these stands was developed.
Sharma and Amateis et al. 2002. For. Ecol. Manage. 168: 163-175.
Author Keywords
Pinus taeda; Site productivity; Forest growth
Random-Effects Models for Serial Observations with Binary Response
Robert Stiratelli
Computer Applications Research Department, Rohm and Haas Research
Laboratories, 727 Norristown Road, Spring House, Pennsylvania 19477, USA
Nan Laird, James H. Ware
Harvard School of Public Health, 677 Huntington Avenue, Boston,
Massachusettes 02115, USA
Abstract
This paper presents a general
mixed model for the analysis of serial dichotomous responses provided by a panel
of study participants. Each subject's serial responses are assumed to arise from
a logistic model, but with regression coefficients that vary between subjects.
The logistic regression parameters are assumed to be normally distributed in the
population. Inference is based upon maximum likelihood estimation of fixed
effects and variance components, and empirical Bayes estimation of random
effects. Exact solutions are analytically and computationally infeasible, but an
approximation based on the mode of the posterior distribution of the random
parameters is proposed, and is implemented by means of the EM algorithm. This
approximate method is compared with a simpler two-step method proposed by Korn
and Whittemore (1979, Biometrics 35, 795-804), using data from a panel study of
asthmatics originally described in that paper. One advantage of the estimation
strategy described here is the ability to use all of the data, including that
from subjects with insufficient data to permit fitting of a separate logistic
regression model, as required by the Korn and Whittemore method. However, the
new method is computationally intensive.
Stiratelli and Laird et al. 1984. Biometrics 40: 961-971.
Forecasting wood resources on the basis of national forest inventory
data. Application to Pinus pinaster Ait. in southwestern France
Raúl Salas-González
Instituto de Ecología, Universidad Nacional Autónoma de México, Ap.
Postal 70–275, 04510, México D.F. and Escola Superior Agrária de Coimbra, Departamento Florestal, Instituto
Politécnico de Coimbra, Bencanta 03040, Coimbra, Portugal
Francois Houllier
CIRAD, Unité mixte de recherches CIRAD–INRA Modélisation des plantes
(AMAP), Campus international de Baillarguet TA 40/E, 34398 Montpellier Cedex 5,
France
Bernard Lemoine
INRA. Unité de recherches forestières, BP 45. Gazinet, Pierroton, 55610
Cestas, France
Gérome Pignard
Inventaire Forestier National, Place des Arcades, BP 1, 34970 Maurin-Lattes,
France
Abstract
The
objective of this paper is to propose a method for simulating and predicting the
evolution of wood resources in the ‘Landes de Gascogne’ region. Lemoine’s
growth and yield model has been successfully utilized to predict future timber
resources from existing
data
collected in two successive surveys (1977 and 1988) conducted by the National
Forest Inventory (NFI). Lemoine’s model was
calibrated
by analyzing the error in estimation of stand features between the NFI plots and
experimental plots originally used to built Lemoine’s model. The proposed
corrected term is based on the best linear unbiased predictor of the error. The
calibrated model exhibited a better accuracy than the original model version. We
suggest that coupling the calibrated Lemoine’s model with NFI data is a useful
method for predicting timber resources at a regional level. Salas-González and Houllier
et al. 2001. Ann.
For. Sci. 58: 785-802.
Key
words
wood resource, national forest
inventory, growth model, model calibration, maritime pine
Selecting a Level of Conditioning for the Segmented
Polynomial Taper Equation
Mahadev
Sharma
Forintek Canada Corp. 319 rue Franquet, Sainte-Foy, QC, G1P
4R4, Canada
Harold E. Burkhart
Department of Forestry, Virginia Polytechnic Institute and
State University, Blacksburg, VA 24061
Abstract
Using
tree data collected from loblolly pine thinning study plots, different levels of
conditioning were examined for the segmented polynomial taper equation presented
by Max and Burkhart (1976). An eight-parameter model with minimum constraints
(diameter at the tip of a tree is zero and the adjacent functions are continuous
at the join points) did not perform better than a six-parameter model with an
additional smoothness constraint in terms of fit and predictive ability. The
join points where the adjacent segments of a tree meet, the inflection points,
were assumed known to further reduce the number of parameters in the model. A
four-parameter model with inflection points at 11 and 75% of total tree height
was slightly superior to the six and eight-parameter models in estimating tree
diameters. The fit statistics and predictive ability of the model were not
sensitive to the lower and upper inflection points in the range of 9–12% and
70–80%, respectively. Sharma and Burkhart 2003. For. Sci. 49(2):324-330.
Key
Words
Tree
volume, tree taper, mensuration, segmented regression, Pinus taeda.
Can
interaction coefficients be determined from census data? Testing two estimation
methods with Negev Desert rodents
Georgy Shenbrot and Boris Krasnov
Ramon Sci. Center, Jacob Blaustein Inst. for Desert Res., Ben-Gurion
Univ. of the Negev, Mizpe Ramon, P.O. Box 194, IL- 80600 Israel
Abstract
Two
approaches based on regression models are proposed to estimate competition from
census data. The ‘‘static’’ approach is based on censuses of population
sizes among species at one point in time over many sites. The
‘‘dynamic’’ approach relies on a time series of species abundance data
to examine whether per capita changes in one species are associated with the
abundance of other species. We estimated competition interactions in a Negev
rodent community consisting of 10 species using both approaches, basing on 8
years (16 half-year periods) of observations. The static approach revealed
significant competitive interactions in four of 45 pairs of species, whereas the
dynamic approach did so in the same four plus two more pairs. For each species
pair, both approaches revealed significant negative interactions in only 1–4
of 16 seasons. The static approach provided nearly symmetric estimations of
competition, whereas estimations of dynamic approach were asymmetric. Moreover,
estimations of the two approaches did not coincide in time. Cases of negative
interactions recorded by the static approach were more frequent at peak and
increase phases of population density dynamics, whereas those recorded by the
dynamic approach were more frequent at peak and decline phases. Results of field
removal experiments with Mus musculus and Gerbillus dasyurus supported
predictions of dynamic but not static approaches. We hypothesized that in harsh
and fluctuating desert environments that disrupt equilibrium, the dynamic
approach indicates true (exploitation) competition, whereas the static approach
reflects negative interspecific spatial association (interference).
Shenbrot and Krasnov2002. OIKOS
99: 47–58.
Contribution
of Increasing CO2 and Climate to Carbon Storage by Ecosystems in the
United States
David
Schimel
Max-Planck-Institute
for Biogeochemistry, Postfach 100164, D-07701 Jena, Germany
Jerry
Melillo, Hanqin Tian
The
Ecosystems Center, Marine Biological Labortory, Woods Hole, MA 02543, USA
A.
David McGaire
US
geological Survey, Alaska Cooperative Fish and Wildlife Research Unit,
University of Alaska, Fairbanks, AK 99775-7020
David
Kicklight
The
Ecosystems Center, Marine Biological Labortory, Woods Hole, MA 02543, USA
Timothy
Kittel, Nan Rosenbloom
National
Center for Atmospheric Research, P.O. Box 3000, Boulder, CO 80307-3000, USA
Steven
Running, Peter Thornton
University
of Montana, Missoula, MT 59812, USA
Bennis
Ojima, William Parton, Robin Kelly
NREL,
Colorado State University, Fort Collins, CO 80523-1499, USA
Martin
Sykes
Plant
Ecology, Lund University, Ekologihuset 223 62 Lund, Sweden
Ros
Neilson
U.S.
Department of Agriculture, Forest Service, Oregon Sate University, Forest
Science Laboratory, 3200 Southwest Jefferson
Way, Corvallis, OR 97333 USA
Brian
Rizzo
Department
of Environmental Sciences, University of Virginia, Charlottesville, VA 22903,
USA
Abstract
The effects of increasing carbon
dioxide (CO2) and climate on net carbon storage in terrestrial
ecosystems of the conterminous United States for the period 1895-1993 were
modeled with new, detailed historical climate information. For the period
1980-1993, results from an ensemble of three models agree within 25%, simulating
a land carbon sink from CO2 and climate effects of
0.08 gigaton of carbon per year. The best estimates of the total sink from
inventory data are about three times larger, suggesting that processes such as
regrowth on abandoned agricultural land or in forests harvested before 1980 have
effects as large as or larger than the direct effects of CO2 and climate. The modeled sink varies by about 100%
from year to year as a result of climate variability.
Schimel
and Melillo et al. 2000
Scinece : 287: 2004-2005.
Forest
Volume-to-Biomass Models and Estimates of Mass for Live and Standing Dead Trees
of U.S. Forests
James
E. Smith, Linda S. Heath
Northeastern
Research Station at Durham, New Hampshire, United States Department of
Agriculture Forest Service
Jennifer
C. Jenkins
Northeastern
Research Station at Burlington, Vermont, United States Department of Agriculture
Forest Service
Abstract
We
present methods and equations for nationally consistent estimates of tree-mass
density at the stand level (Mg/ha) as predicted by growing-stock volumes
reported in USDA Forest Service surveys for forests of the conterminous United
States. Developed for use in FORCARB, a carbon budget model for U.S. forests,
the equations also are useful for converting stand-, plot-, and regional-level
forest merchantable volumes to estimates of total mass. Tree biomass is about 50
percent carbon, so carbon estimates can be derived from estimates of biomass by
multiplying by 0.5. We include separate equations for live and standing dead
trees. Similarly, separate equations predict the components of aboveground only
vs. full trees (including coarse roots) and hardwood vs. softwood species.
Equations are developed for broad forest types by region and are applicable to
large-scale forest inventory data. Example estimates are provided for regional
tree-mass totals using summary forest statistics for the United States.
Smith and Heath et al. 2003.
USDA Forest
Service Northeastern
Research
Station
Gen. Tech. Rep.NE-298
Allometric
Biomass Equations for 98 Species of Herbs, Shrubs, and Small trees
W. Brad Smith, Gary J. Brand
USDA Forest Service, North Central Forest Experiment Station, 1992 Flwell
Ave. St. Paul, MN 55108
Abstract
Biomass
regression coefficients from the literature for the allometric equation form are
presented for 98 species of shrubs and herbs in the northern U.S. and Canada.
The equation and coeffients provide estimates of grames fo biomass (oven-dry
weight) for foliage, woody stem and total biomass. Smith and Brand
1983. USDA
Research note NC-299.
Key
words
Regression,
Metric, dry weight, herbs, shrubs
A Model of Forest Floor Carbon Mass for United States Forest
Types
James E. Smith, Linda S. Heath
USDA Forest Service, Northeastern Research Station at
Durham, New Hampshire
Abstract
We
summarize a large set of published values of forest floor mass and develop
large-scale estimates of carbon mass according to region and forest type.
Published values of forest floor carbon mass or information relevant to
compiling such summaries are scarce. We present a simulation model based on
observations obtained from literature surveys for use in the 2002 version of
FORCARB, a carbon budget model for U.S. forests. The forest floor is the
distinct layer of dead and decaying plant material that accumulates on the soil
surface, which lies above the mineral soil and includes small woody debris.
Estimates of average forest floor carbon mass per hectare of forest applied to a
1997 summary forest inventory, sum to 4.5 Gt carbon stored in forests of the 48
contiguous United States.
Smith and Heath 2002. USDA, Forest Service, Northeastern
Research
Station
Res. Pap. NE-722
The
spatial manifestation of forest succession in optical imagery
The
potential of multiresolution imagery
Conghe
Song
Department
of Geography, The University of North Carolina at Chapel Hill, CB# 3220, 203
Saunders Hall, Chapel Hill, NC 27599, USA
Curtis
E. Woodcock
Department of Geography, Boston University, 675 Commonwealth Avenue, Boston, MA
02215, USA
Abstract
Forest succession is a fundamental ecological
phenomenon, which has significant implications for sustainable ecosystem
management as well as biological, biophysical, and biogeochemical processes.
Remote sensing is perhaps the only viable option for monitoring changes in
forest ecosystems over large areas in a timely and cost efficient manner. This
study investigates the spatial manifestation of forest succession in optical
imagery through three types of models: a two-component spatial model, a canopy
reflectance model (Geometric–Optical and Radiative Transfer, GORT) and a
forest ecosystem dynamics model (ZELIG). The latter two models provide inputs to
the former one to predict the spatial properties of images as a function of the
combined effects of tree size and density, the spectral signatures of scene
components and pixel size. An important source of information that is diagnostic
of canopy structure has been identified: the spatial properties of
multiresolution imagery. The sill of variograms of images of forest stands
decrease with regularization, and in particular the rate of decrease is related
to the size of trees. For stands with larger trees the sills of variograms
decrease more slowly with increasing regularization than for stands with smaller
trees. However, the spatial patterns for a scene with multiresolution imagery
are also dependent on tree cover. This implies that the use of spatial patterns
to estimate tree size will require independent estimates of tree cover as a
preliminary step. Concept verification with an Ikonos 1-m panchromatic image for
stands at the H.J. Andrews Experimental Forest in the Cascade Range of Oregon
indicates the simulated spatial patterns exist in multiresolution imagery. This
study demonstrates the potential to map tree size automatically from
multiresolution imagery. Song and Woodcock 2002.
Remote Sens. Environ. 82: 271-284.
Forest inventories and growth models to examine
management strategies for forests in transition
Hubert
Sterba
Institute
of Forest Growth Research, University of Agricultural Sciences in Vienna, Peter
Jodanstrasse 82, A-1190 Vienna, Austria
Abstract
For determining the amount and structure of the allowable cut in forests in
transition (from even-aged to uneven-aged management) the assumptions of the
usual formulas for calculating allowable cut no longer apply. In this situation,
growth models applied to permanent sample inventories become an important
planning tool. This is demonstrated at a forest management district in the
Austrian part of the Bohemian Massif, where clear-cutting was abandoned 40 years
ago. The existing inventory is based on angle counts. The site mapping,
performed there in 1963, is translated into the site factors used in the growth
simulator PROGNAUS, using a sample of site assessments in the mapped site
classes. The simulation results, for four different harvesting regimes over 80
years, are evaluated to find the most appropriate harvesting level.
Sterba 2002. For. 75:411-418.
Automated
Forest Structure Mapping from High Resolution Imagery Based on Directional
Semivariogram Estimates
Benoît
A. St-Onge
Department
of Geography, Université du Québec à Montréal Montréal, Québec Canada
François
Cavayas
Department of Geography, Université de Montréal Montréal, Québec Canada
Abstract
A new segmentation approach that allows forest stands
identification on high spatial resolution (
1
m) optical imagery is presented. Texture information was first derived by
measuring the range of the semivariogram of monochrome image values in three
different directions using a moving window. The semivariogram ranges were then
used to predict, on a per-pixel basis, three stand structure parameters through
regression equations developed for crown diameter, stand density, and crown
closure. A region growing algorithm was applied to these three regression
estimate images to identify the limits of the forest stands. Calibration of the
prediction equations was made using artificial images created by a
geometrical-optical process. It was found that forest stands boundaries can be
adequately identified on artificial images and that average forest structure
estimates within each delineated stand are close to the actual values.
Preliminary application of the proposed method to real images acquired with the
MEIS-II airborne sensor yielded good segmentation and per stand structure
estimates. Some errors were generated due to the fact that the moving window
sometimes overlapped two different forest stands because of the presence of
areas covered by non-forest vegetation or human made structures. The issue of
the moving window size and means to increase the precision of the method are
discussed.
St-Onge and
Cavayas 1997. Remote Sens. Environ. 61: 82-95.
The financial costs of defoliation of Scots pine (Pinus
sylvestris) by pine looper moth (Bupalus piniaria)
N.A.
Straw
Forestry
Commission Research Agency, Alice Holt Lodge, Wrecclesham, Farnham, Surrey GU10
$LH, England
H.L.
Armour, K.R. Day
Environmental
Research Unit, University of Ulster, Coleraine BT 521SA, Northern Ireland
Abstract
The financial costs of defoliation of Scots pine by the pine looper moth (Bupalus
piniaria L.) were evaluated for three pine stands in Tentsmuir Forest,
Scotland, by comparing observed tree growth with estimates of the growth that
would have been expected if the moth had not been present. It was calculated
that five or seven periods of partial defoliation, caused by successive peaks in
the moth population, had reduced the total volume of marketable timber available
in thinnings and at final harvest by 26-35 m3 ha-1. Nearly
all of this loss occurred in the sawlog category of timber. Total discounted
income over the rotation, based on long-term (1984-2001) average timber prices
and a 3.5 per cent discount rate, was reduced by 5.8-7.5 per cent when the same
rotation length was used for both observed and expected growth. At a discount
rate of 6 per cent, total income was reduced by 4.4-5.2 per cent. Extending the
rotation by 3 or 4 years to allow the mean final tree size to reach that
expected in the absence of defoliation, or by 4 or 6 years to allow the same
total volume of timber to be extracted, increased total revenue but did not
increase gross discounted income because of the effect of discounting over a
greater number of years.
Straw and Armour et al. 2002. 75: 525-536.
Clearcutting and burning of northern
spruce-fir forests: implications for small mammal communities
Thomas
P. Sullivan
Department
of Forest Science, Faculty of Forestry, University of British Columbia,
Vancouver, BC, Canada V6T 1Z4
R.
A. Lautenschlager, Robert G. Wagner
Ontario
Forest Research Institute, 1235 Queen Street East, Sault Ste. Marie, Ontario,
Canada P6A 2E5
Abstract
1.
This study was designed to test the hypotheses that (i) abundance and related
demographic parameters of small mammal populations would decline after
clearcutting of northern spruce-fir forest, and (ii) prescribed burning,
following clearcutting, an approach to emulating natural disturbance, would
enhance the species richness and diversity of the small mammal community
relative to unharvested and clearcut forests.
2. Intensive live-trapping of small mammal populations was conducted in
replicated forest (uncut), clearcut and clearcut-burned sites from 1988 to 1992
in west-central British Columbia, Canada.
3. Mean abundance of southern red-backed voles Clethrionomys gapperi
was significantly higher on forest sites (11·74 ha-1) than on
clearcut (0·60 ha-1) or clearcut-burned (0·02 ha-1)
sites. Mean numbers of deer mice Peromyscus maniculatus were
significantly higher on the clearcut-burned sites (16·88 ha-1) than
on forest sites (9·04 ha-1). Demographic parameters of reproduction,
survival and body weight of deer mice were similar across all sites.
4. The long-tailed vole Microtus longicaudus had a strong annual
fluctuation in abundance, particularly on clearcut sites (14·04 ha-1),
where there were significantly more animals than on either forest (1·53 ha-1)
or clearcut-burned (2·67 ha-1) sites. Meadow voles M.
pennsylvanicus were relatively uncommon but occurred more often on clearcut
and clearcut-burned sites than on forest sites.
5. The north-western chipmunk Tamias amoenus occurred at
significantly higher numbers on clearcut (4·16 ha-1) and clearcut-burned
(3·88 ha-1) sites than on forest sites, where it was rarely
captured. Shrews Sorex spp. were at similar numbers across forest,
clearcut and clearcut-burned sites. Weasels Mustela spp. were captured
more often on clearcut and clearcut-burned sites than on forest sites. A rare
species, the western jumping mouse Zapus princeps, was captured on
clearcut and clearcut-burned sites only.
6. Mean species richness of small mammals was significantly higher on
clearcut sites (3·51) than on forest (2·73) or clearcut-burned (2·72) sites.
Species diversity was similar over all sites. Although species composition was
altered by clearcutting, abundance of all species, except C. gapperi, was
the same or higher than that in uncut forest.
7. Prescribed burning of clearcuts may not be necessary to mimic natural
disturbance regimes. Clearcutting of northern spruce-fir forest may provide
diverse habitats for small mammals through different stages of succession (along
with old growth forest) much as wildfires formerly did.
Sullivan and Lautenschlager et al. J. Appl. Ecol. 1999. 36: 327-344.
Keywords
Demography;
forest harvesting; Picea-Abies forests; population density; species diversity
Estimation
of timber volume in a coniferous plantation forest using Landsat TM
C.
M. Trotter, J. R. Dymond
Landcare
Research, Private Bag 11052, Palmerston North, New Zealand
C.
J. Goulding
New
Zealand Forest Research Institute, Private Bag 3020, Rotorua, New Zealand
Abstract
Optimization
of economic return from forests requires that comprehensive forest inventory
data be available to support the design of harvesting strategies. Such inventory
data can potentially be obtained by remote sensing. This study investigates the
accuracy with which wood volume (m3 ha-1) in a plantation
forest can be calculated from Landsat TM data at the pixel and forest stand
spatial scales. Wood volumes were estimated from regression analysis,
nonparametric line-fitting, and an N-dimensional K-nearest-neighbour
classification scheme. At the pixel scale, relations between Landsat data and
measured wood volume were found to be significant but weak, with r2
values of 0.3, and with correspondingly poor estimates of wood volume
(root-mean-square errors rmses of 100 m3 ha -1). By
averaging the pixel-scale estimates, wood volume estimates of acceptable
accuracy were obtained for forest-stand areas of about 40 ha (rmses of <=46 m3
ha -1). Parametric regression performed slightly better overall than
non-parametric line fitting techniques for estimating wood volume. Estimates of
similar accuracy to those obtained by regression were also given by NK-classification
at the pixel-scale, provided K was large (>=15), although the classifier
produced biased results at the forest-stand scale. It is concluded that Landsat
TM only provides an acceptable data source for estimating wood volumes in
plantation forests for areas of about 40 ha and larger. The very low dynamic
range in the Landsat data is probably a significant factor limiting its use for
inventory at more detailed scales.
Trotter and Dymond et al. 1997. Int. J. Remote Sens. 18: 2209 – 2223.
Imputing
tree-lists from aerial attributes for complex stands of south-eastern British
Columbia
H.
Temesgen, V. M. LeMay, K. L. Froese,
P. L. Marshall
Department of Forest Resources Management, University of British Columbia,
2045-2424 Main Mall, Vancouver, BC, Canada V6T 1Z4
Abstract
The nearest neighbor, k-nearest neighbors,
distance-weighted k-nearest neighbor, and class-weighted k-nearest
neighbor imputation methods were compared for accuracy in estimating tree-lists
(list of species and diameter for each tree) from aerial attributes for complex
stands, with up to nine species and a wide range of sizes, in south-eastern
British Columbia, Canada. For the four imputation methods, the most similar
neighbor distance metric was used, and three neighbors were used for the k-nearest
neighbor methods. Ground variables used to represent the tree-list included the
number of trees per hectare by species, ranges of diameter by species, and basal
area per hectare. Aerial variables included species composition, crown closure
(%), elevation, biogeoclimatic ecosystem classification (BEC) zones, height,
age, and site class. Sample data were divided, and the imputation methods were
compared for accuracy using observed and estimated species composition, stand
tables, basal area, and volume per hectare. Also, the imputed tree-list was used
to predict yield using a stand level growth model, and this predicted yield was
compared to the yield obtained using the actual tree-list. Of the four
approaches used, the nearest neighbor was marginally better, but the methods
that averaged the three nearest neighbors were somewhat better for the
distribution of stems per hectare by diameter for the more sparse hardwood
species. Of the three averaging methods, weighting by similarity of the species
composition and the BEC zone provided better results. In using the estimated
trees lists in a growth and yield model, the average volumes were reasonable at
the beginning and end of the period for all methods. However, the volumes for a
particular stand could be quite different than that obtained for an observed
tree-list. Temesgen and LeMay et al. 2003. For. Ecol. Manage. 177:
277-285.
Author Keywords
Imputation; Tree-lists; Aerial data; Complex stands
Biomass and Taper for Trees in Thinned and Unthinned Longleaf Pine
Plantations
Charles
E. Thomas, Bernard R. Parresol, Kim H. N. Lê
USDA
Forest Service, Southern Forest Experiment Station, Institute for Quantitative
Studies, New Orleans, LA 70113
Richard
E. Lohrey
USDA
Forest Service (retired), Southern Forest Experiment Station, Pineville, LA
71360
Abstract
Longleaf pine (Pinus palustris Mil1.)
trees growing in thinned plantation studies in Louisiana and Texas and unthinned
stands from the Louisiana sites were sampled for establishing taper, volume, and
specific gravity. Stem analysis data were collected on 147stems ranging in age
from 30 to 50 yr. Analyses of covariance (ANCOVAs) were employed to determine
coefficients and to detect differences among treatments, for tree taper and
specific gravity. Taper and volume equation coefficients and statistics at
specified ages were developed for intermediate plantation ages by examining and
aging internal growth rings from the stem sections. Biomass was computed by
combining the taper and specific gravity equations. Seemingly unrelated
regression (SUR) was used to simultaneously fit the system off our equations
composed of specific gravity, taper, volume, and biomass, because of the
correlated error structure of these equations. Biomass equations, however, could
not be developed for the intermediate ages because specific gravity could not be
determined or related to earlier tree ages. Thomas and Parresol et al. 1995. South. J. Appl. For.
19: 29-35.
Biomass
Equations for Major Tree Species of the Northeast
Louise
M. Tritton
Connecticut
Arboretum at Connecticut College, New London, CT
James
W. Hornbeck
USDA
Forest Service, Northeastern Forest Experiment Station, Durham, NH
Abstract
Regression equations are used in both
forestry and ecosystem studies to estimate tree biomass from field measurements
of dbh (diameter at breast height) or a combination of dbh and height.
Literature on biomass is reviewed, and 178 sets of published equations for 25
species common to the northeastern United States are listed. On the basis of
these equations , estimates fo aboveground oven-dry weight of trees from 2.5 to
50.0 cm dbh for each species are presented and discussed. When general estimates
of standing crop are required for commercial purposes or for assessment of
nutrient removal by tree harvest, the published equations may be used with
precaution instead of developing new equations. When statistical comparison o f
productivity or the ecology of site types are required, published equations
probably are not suitable and development of site-specific equations is
recommended.
Tritton and Hornbeck 1982. USDA Forest Service, Northeastern
Forest Experiment Station, General Technical Report NE-69.
David
P. Turner, Greg J. Koerper
ManTech
Environmental Research Services Corporation, USEPA Environmental Research
Laboratory, Corvallis, Oregon 97333 USA
Mark
E. Harmon
Department
of Forest Science, Oregon State University, Corvallis, Oregon 97333 USA
Jeffrey
J. Lee
United
States Environmental Protection Agency, USEPA Environmental Research Laboratory
Corvallis, Oregon 97333, USA
Abstract
The
potential need for national-level comparisons of greenhouse gas emissions, and
the desirability of understanding terrestrial sources and sinks of carbon, has
prompted interest in quantifying national forest carbon budgets. In this study,
we link a forest inventory database, a set of stand-level carbon budgets, and
information on harvest levels in order to estimate the current pools and flux of
carbon in forests of the conterminous United States. The forest inventory
specifies the region, forest type, age class, productivity class, management
intensity, and ownership of all timberland. The stand-level carbon budgets are
based on growth and yield tables, in combination with additional information on
carbon in soils, the forest floor, woody debris, and the understory. Total
carbon in forests of the conterminous U.S. is estimated at 36.7 Pg, with half of
that in the soil compartment. Tree carbon represents 33% of the total, followed
by woody debris (10%), the forest floor (6%), and the understory (1%). The
carbon uptake associated with net annual growth is 331 Tg, however, much of that
is balanced by harvest-related mortality (266 Tg) and decomposition of woody
debris. The forest land base at the national level is accumulating 79 Tg/yr,
with the largest carbon gain in the Northeast region. The similarity in the
magnitude of the biologically driven flux and the harvest-related flux indicates
the importance of employing an age-class-based inventory, and of including
effects associated with forest harvest and harvest residue, when modeling
national carbon budgets in the temperate zone.
Turner and Koerper et al. 1995. Ecol. Appl. 5: 421-436.
Woody Biomass Methods
for Estimating Change
Brian Turner, Kim Wells, Jürgen Bauhus, Geoff Carey, Cris Brack, Peter
Kanowski
Department of Forestry, School of Resource Management and
Environmental Science,The Australian National University
Canberra, ACT 0200
Abstract
The
brief for this Consultancy was to assess the utility and quality of existing
data, methods and techniques for 14 specific components of the estimation of
biomass needed to address the 1990 baseline year requirements of the Kyoto
Protocol. In addition, we were to consider the potential of emerging
technologies for future improvements in the data needed to meet Australia’s
international obligations. We have determined that data for the following
components are readily available, although they may not always be accessible for
political or commercial reasons:
•
age class of plantations;
•
growth increments of plantations;
•
area of commercial plantations;
•
area of plantations harvested; and
•
area of plantations established.
For
the following components, the information is difficult to obtain, but the
contribution of the component to the 1990 baseline is so minor that
approximations should be adequate:
•
fuelwood extracted from managed forests;
•
likely time to maturity, and biomass at maturity, of environmental plantings;
and
•
area of environmental plantings.
For
the remaining components, to improve current estimates significant additional
information and analysis is needed:
•
growth increments of managed native forests no longer available for harvest;
•
biomass removed, or put into decay, by previous land clearing;
•
proportion of forest cleared that was mature and proportion that was regrowth;
•
age and rates of accumulation of ‘recleared’ areas (i.e., regrowth that is
being cleared);
•
expansion factors, from rounded volume or wood product, to estimate total
biomass removed and total biomass left to decay on site; and
•
methods to calculate a continental biomass stock.
In
most cases the missing information is related to improving knowledge of the
allometric relationships between measurable attributes or available information
and biomass. It is our view that precision of the final estimates hinges on two
areas: the assigning of net primary productivity values to the various
vegetation classes; and the partitioning of biomass to above- and below-ground.
We believe that these areas, together with methods for quantifying the precision
of estimates, should be given priority in the near future. Significant
improvements in process modeling and satellite data collection systems over the
next decade can be expected to allow major improvements in biomass estimations.
It is these areas where most future work is needed.
Turner and Wells
1999. National
Carbon Accounting System Technical Report No. 3 August 1999.
Mixed-Effects Nonlinear Regression for Unbalanced Repeated Measures
Edward
F. Vonesh
Applied Statistics Center, Baxter Healthcare Corp., P.O. Box 490, Round
Lake, Illinois 60073, U.S.A
Randy L. Carter
Department of Statistics, Division of Biostatistics, University of
Florida, Gainesville, Florida 32610, USA
Abstract
Repeated
measures data, such as clinical pharmacokinetic data, growth data, and
dose-response data, are often inherently nonlinear with respect to a given
response function and are frequently incomplete and/or unbalanced. Nonlinear
random-effects models together with a variety of estimation procedures have been
proposed for the analysis of such data. This paper is concerned with a
straightforward procedure for estimating and comparing the parameters of a
generalized mixed-effects nonlinear regression model. The asymptotic properties
of the proposed estimators are given and large-sample tests of hypotheses
provided. The results are applied to in
vitro data on
the water transport kinetics of hemodialyzers used in the treatment of patients
with chronic renal failure.
Vonesh and Carter et al. 1992. Biometrics 48: 1-17.
Consistent Estimation of Site Index Curves Fitted to Temporary Plot Data
David K. Walters, Timothy G. Gregoire, Harold E. Burkhart
Department of Forestry, Virginia Polytechnic Instituyte and State
University, Blacksburg, Virginia 24061
Abstract
Instrumental variable estimation
is presented as an alternative to ordinary least squares when only temporary
plot data are available to fit site index curves. With an instrument that is
uncorrelated with site index but positively correlated with age, consistent
coefficient estimates can be obtained. Misspecification tests developed by
Hausman (1978, Econometrica 46, 1251-1271) and Feldstein (1974, Journal of the
American Statistical Association 69, 990-996) are presented which can be used to
help decide when instrumental variable estimation is superior to ordinary least
squares. Measures of stand density may provide effective instruments for curve
fitting because site index is usually unaffected by density. But of five data
sets examined, only one provided an effective instrument of this sort. In this
one case, however, the instrumental variable estimates were significantly better
than those obtained through the more conventional procedure.
Walters and Gregoire et al. 1989. Biometrics 23-33.
Biomass Estimation Errors Associated with the Use of Published
Regression Equations of Paper Birch and Trembling Aspen
J.R. Wang,
Faculty of Forestry and the Forest Environment, Lakehead University,955
Oliver Road, Thunder Bay, Ontario Canada P7B 5E1
A.L. Zhong, J.P. Kimmins
Department of Forest Sciences, University of British Columbia, 2424 Main
Mall, Vancouver, BC. Canada V6T1Z4.
Abstract
Since forest biomass contributes a
significant proportion of global carbon cycle, obtaining accurate estimate of
forest biomass is important. The root mean squared error (RMSE), the percents of
the mean observed values were used to compare the precision of local and
published biomass equations for paper birch and trembling aspen. With the
exception of stemwood biomass equations, the biomass equations for these two
species tended to be stand specific. Measured as percent of mean observed
values, the values of biomass/tree predicted from the published equations for
paper birch varied from 49.9% to 140.2% for foliage and from 155%
to
238.7% for live branches; the estimates for trembling aspen ranged from 71.8% to
81.3% for foliage and from 55.3% to 164.5% for live branches. There were large
discrepancies between the measured data and the published equations in graphical
form as well as biomass estimates, particularly for foliage, live branches, and
stembark. Clearly, published regression equations should be checked for their
applicability before they are used to estimate the biomass of particular stands.
Wang and Zhong et al. 2002. North. J. Appl. For. 19: 128–136.
Key
Words
Biomass,
equation, paper birch, aspen, estimation error.
Donald
E. Weller, Thomas E. Jordan, David L. Correll
Smithsonian
Environmental Research Center, 647 Contees Wharf Road, P.O. Box 28, Edgewater,
Maryland 21037-0028 USA
Abstract
For
landscapes with riparian buffers, we develop and analyze models predicting
landscape discharge based on material release by an uphill source area, the
spatial distribution of riparian buffer along a stream, and retention within the
buffer. We model the buffer as a grid of cells, and each cell transmits a fixed
fraction of the materials it receives. We consider the effects of variation in
buffer width and buffer continuity, quantify the relative contributions of
source elimination and buffer retention to total discharge reduction, and
develop statistical relationships to simplify and generalize the models. Width
variability reduces total buffer retention, increases the width needed to meet a
management goal, and changes the importance of buffer retention relative to
source elimination. Variable-width buffers are less efficient than uniform-width
buffers because transport through areas of below-average buffer width
(particularly gaps) dominates landscape discharge, especially for narrow buffers
of highly retentive cells. Uniform-width models overestimate retention, so width
variability should be considered when testing for buffer effects or designing
buffers for water quality management. Adding riparian buffer to a landscape can
decrease material discharge by increasing buffer retention and by eliminating
source areas. Source elimination is more important in unretentive or wide
buffers, while buffer retention dominates in narrow, retentive buffers. We
summarize model results with simpler statistical relationships. For unretentive
buffers, average width is the best predictor of landscape discharge, while the
frequency of gaps was best for narrow, retentive buffers. Together, both
predictors explain >90% of the variance in average landscape transmission for
any value of buffer retentiveness. We relate our results to ecological theory,
landscape-scale buffer effects, buffer management, and water quality models. We
recommend more empirical studies of buffer width variability and its effects on
material discharge. Landscape models should represent width variability and the
nonlinear interactions between buffers and source areas.
Weller and Jordan et al. 1998. Ecol. Appl. 8: 1156-1169.
Key words
Grid cell; landscape ecology; landscape index; model;
nonpoint source pollution; nutrient discharge; raster; riparian buffer; riparian
management; scaling; sediment discharge; water quality.
Satellite
Evidence of Phenological Differences between Urbanized and Rural Areas of the
Eastern United States Deciduous Broadleaf Forest
Michael
A. White
Department of Geography and Earth Resources, Old Main Hall 5240, Utah
State University, Logan, Utah 84322-5240, USA
Ramakrishna
R. Nemani
NTSG/Forestry, University of Montana, Missoula, Montana 59812, USA
Peter
E. Thornton
National Center for Atmospheric Research, Climate and Global Dynamics
Division, Boulder, Colorado 80307, USA
Steven
W. Running
NTSG/Forestry, University of Montana, Missoula, Montana 59812, USA;
Abstract
We
used a 10-year record (1990–99) of composited and cloud-screened reflectances
from the Advanced Very High Resolution Radiometer (AVHRR) to test for
phenological differences between urban and rural areas in the eastern United
States deciduous broadleaf forest (DBF). We hypothesized that welldocumented
urban heat island effects would be associated with alterations in
temperature-sensitive vegetation phenology. Our objectives were thus (a) to
investigate possible differences in the start of the growing season (SOS) and
end of the growing season (EOS) between the urban and DBF land covers, (b) to
investigate related differences in greenness amplitude and fractional cover, and
(c) to develop a generalized additive model (GAM) to predict the spatial
variation of observed differences. By analyzing individual 1° latitude by 1°
longitude blocks, we found that, on average, urbanization is associated with a
growing season expansion of 7.6 days. Most of this effect is caused by an
earlier SOS in urban areas. In all cases, urban regions had lower fractional
cover and greenness amplitude. The GAM model failed to produce a viable model
for differences in EOS, probably because it is dominated by photoperiod controls
with only a minor temperature impact. SOS differences were predicted with an
accuracy of about 2.4 days, with a GAM consisting of smoothed functions of mean
annual average temperature, urban fractional cover, and the urban vs DBF
greenness amplitude difference. We speculate that evidence of a phenological
response to warming indicates that global warming, without reduction in DBF
vegetation cover and greenness amplitude, may increase carbon sequestration in
mesic deciduous forests.
White and Nemani et al. 2002.
Ecosystems 5: 260–277.
Key
words
phenology;
urbanization; urban climate; Advanced Very High Resolution Radiometer (AVHRR);
normalized difference vegetation index (NDVI); deciduous broadleaf forest.
The climatic signal in tree-rings of Scots pine (Pinus sylvestris L.)
from foot-hills of the Sudetic Mountains (southern Poland)
Von S. Wilczynski
Department of Forest Climatology, Agricultural University of Krakow,
31-425 Krakow, al. 29-Listopada 46, Poland
J. Skrzyszewski
Department of Sylviculture, Agricultural University of Krakow, 31-425
Krakow, al. 29-Listopada 46, Poland
Abstract
Investigations
were carried out in 11 stands of Scots pine (Pinus sylvestris L.) growing
at elevations between 4502750 m in the K³odzko Valley and on foot-hills of the
Karkonosze Mountains. The two regions are located approximately 80 km apart.
However, they are distinctly different in regards to pluvial conditions since
the K³odzko Valley is located in the rain shadow of the mountain ranges to the
west and south. In each stand two increment cores per tree were extracted from
20 trees and the tree-ring widths were measured. The relationship between
thermal and pluvial conditions and tree-ring width was analysed, using methods
of correlation, response function (FRITTS 1976), coefficient of agreement (ECKSTEIN
and BAUCH
1969) and
principal components analysis (HOLMES
1994). The
thermal and pluvial conditions of the growing season and in the months preceding
it had a significant effect on pine tree-ring width in both regions. High
temperatures in late winter (February, March) and in summer (July, August) had a
positive effect, while high precipitation in January, April and September had a
negative effect on the radial increment of the trees. The pines in the K³odzko
Valley, growing in a rain shadow, showed a greater need for rain during the
growing season (May-August) than trees on the foot-hills of the Karkonosze
Mountains (only July). Thermal conditions in winter had strong but similar
effects on the rhythm of the annual radial increment of the pines, while summer
precipitation proved to be a factor differentiating the treering chronologies.
Wilczynski and Skrzyszewski 2002. Forstw. Cbl. 121: 15-24.
Key
words
Pinus
sylvestris,
dendroclimatology, dendroecology, Sudetes
Heterogeneity of Soils and Vegetation in an Eastern Amazonian Rain
Forest: Implications for Scaling up Biomass and Production
M.
Williams
The Ecosystems Center, Marine Biological Laboratory, Woods Hole,
Massachusetts 02543, USA and Institute of Ecology and Resource Management,
University of Edinburgh, Edinburgh EH9 3JU, Scotland
Y.
E. Shimabukuro
Instituto Nacional de Pesquisas Espaciais, São José dos Campos, SP,
Brazil
D.
A. Herbert
The Ecosystems Center, Marine Biological Laboratory, Woods Hole,
Massachusetts 02543, USA
S.
Pardi Lacruz
Instituto Nacional de Pesquisas Espaciais, São José dos Campos, SP,
Brazil
C.
Renno
Instituto Nacional de Pesquisas Espaciais, São José dos Campos, SP,
Brazil
E.
B. Rastetter
The Ecosystems Center, Marine Biological Laboratory, Woods Hole,
Massachusetts 02543, USA
Abstract
Transferring fine-scale ecological knowledge into an
understanding of earth system processes presents a considerable challenge to
ecologists. Our objective here was to identify and quantify heterogeneity of,
and relationships among, vegetation and soil properties in terra firme rain
forest ecosystems in eastern Amazonia and assess implications for generating
regional predictions of carbon (C) exchange. Some of these properties showed
considerable variation among sites; soil textures varied from 11% to 92% clay.
But we did not find any significant correlations between soil characteristics
(percentage clay, nitrogen [N], C, organic matter) and vegetation
characteristics (leaf area index [LAI], foliar N concentration, basal area,
biomass, stem density). We found some evidence for increased drought stress on
the sandier sites: There was a significant correlation between soil texture and
wood '13C (but not with foliar '13C); volumetric soil
moisture was lower at sandier sites; and some canopy foliage had large, negative
dawn water potentials (Nld), indicating limited water availability in
the rooting zone. However, at every site at least one foliage sample indicated
full or nearly full rehydration, suggesting significant interspecific
variability in drought vulnerability. There were significant differences in
foliar '15N among sites, but not in foliar % N, suggesting
differences in N cycling but not in plant access to N. We used an
ecophysiological model to examine the sensitivity of gross primary production (GPP)
to observed inter- and intrasite variation in key driving variables--LAI, foliar
N, and Nld. The greatest sensitivity was to foliar N; standard errors
on foliar N data translated into uncertainty in GPP predictions up to -10% on
sunny days and -5% on cloudy days. Local variability in LAI had a minor
influence on uncertainty, especially on sunny days. The largest observed
reductions in Nld reduced GPP by 4%-6%. If uncertainty in foliar N
estimates is propagated into the model, then GPP estimates are not significantly
different among sites. Our results suggest that water restrictions in the
sandier sites are not enough to reduce production significantly and that texture
is not the key control on plant access to N. Williams
and Shimabukuro
2002. Ecosystems 5: 692–704.
Key
words
Carbon
and nitrogen isotopes; leaf area index (LAI); gross primary production (GPP);
Large-Scale Biosphere–Atmosphere experiment; soil texture; Amazonia.
Comparison of Ground Sampling Methods for Estimating
Canopy Cover
Michael
S. Williams, Paul L. Patterson
Rocky Mountain Research Station, USDA Forest Service, 2150
A Center Drive, Suite 350, Fort Collins, Colorado 80526
H.
Todd Mowrer
Rocky Mountain Research Station, USDA Forest Service, 240
W. Prospect Road, Fort Collins, Colorado 80526-2098
Abstract
Knowledge
of the canopy structure is essential to improving our understanding of forest
structure. While numerous sampling techniques have been developed to estimate
attributes of the forest canopy, these require either additional measurements or
a sampling design and measurement techniques that differ substantially from the
ones that are used to estimate more traditional forest attributes, such as basal
area, number of stems, or volume. The root of the problem is that the sample
element for a design that estimates canopy attributes is the tree crown, whereas
the sample element is the bole for a design that estimates an attribute such as
basal area. For example, if a fixed-area plot is used to estimate basal area,
canopy cover cannot be estimated using the same design because a portion of the
plot invariably is covered by the crowns of trees whose boles lie outside the
plot boundary and would not be included in the sample under the standard
sampling design. In this study, a technique called “morphing” is used to
model the trees outside the plot boundary. For the purpose of comparison, the
morphing technique is used to estimate canopy cover using data from a circular
fixed-area plot, and this technique is compared with both dot count and line
intersect sampling using a simulation study and two small forest populations.
For the study, the populations were sampled using circular fixed-area plots with
radii ranging from ρ = 3.05–6.10 m (10–20 ft) and line lengths ranging
from L = 3.05–22.9 m (10–75 ft). For both populations, the bias of the
canopy cover estimator derived from the morphing technique was negligible. The
estimator based on line intersect sampling is design-unbiased, but it generally
had a much larger variance than the one based on the morphing technique. The dot
count method consistently had the highest variance. Williams and Patterson et
al. 2003. For.
Sci.
49: 235–246.
Key
Words
Canopy
structure, morphing, torus edge-correction.
Landscape-
vs GAP-level Controls on the Abundance of a Fire-sensitive, Late-successional
Tree Species
Michael
C. Wimberly, Thomas A. Spies
USDA
Forest Service, Pacific Northwest Research Station, 3200 SW Jefferson Way,
Corvallis, Oregon 97331, USA
Abstract
Tsuga heterophylla (western hemlock), a fire-sensitive, late-successional
tree species, is an important component of old-growth forests in the Pacific
Northwest, USA. In the Oregon Coast Range, however, T.
heterophylla
occurs at low densities in or is completely absent from many conifer stands. We
used a cellular automata-based simulation model to explore the influences of the
fire regime and gap disturbances on T. heterophylla dynamics at a landscape scale. The abundance of T.
heterophylla in
the simulated landscape was particularly sensitive to variation in fire return
interval and fire severity. T.
heterophylla was
less sensitive to canopy gap return interval, probability of recruitment in
canopy gaps, and the probability of rare long-distance dispersal events.
Relatively short periods of high fire frequency caused a rapid and persistent
decline in the amount of T. heterophylla in the landscape. Based on the simulation results, we propose two new
hypotheses. The first is that landscape-level constraints imposed by the
frequency, severity, and pattern of wildfires will limit the potential for
gap-level processes to affect T. heterophylla regeneration patterns at the landscape scale. The second, related
hypothesis is that legacies of cumulative fire effects will have a strong
influence on the subsequent development of late-successional forest structure. Wimberly
and Spies 2002.
Ecosystems 5: 232–243.
Susan K. Wiser, Robert K. Peet, Peter S. White
Department
of Biology, CB#3280, University of North Carolina, Chapel Hill, North Carolina
27599-3280, USA
Abstract
Ecologically
sound efforts to manage or reintroduce populations of rare species require
detailed knowledge of species habitat requirements. However, the fact that such
species are rare implies that the data needed for habitat characterization are
sparse and that species might well be absent from favorable sites due to chance
aspects of dispersal or mortality. We use four rare plant species endemic to
southern Appalachian high-elevation rock outcrops, to illustrate how
nonparametric and parametric logistic regression can yield predictive models of
the probability that a species will occur, given certain site conditions. Models
were constructed for each species at two scales: 100-m2 plots and 1-m2
subplots. At the 100-m2 plot scale, absences beyond the current
geographic range were excluded. At the 1-m2 subplot scale, absences
from subplots were only included if the species occurred elsewhere on the 100-m2
plot. Six significant models resulted; no significant model could be
constructed for Solidago spithamaea or Calamagrostis cainii on 1-m2
subplots. For 100-m2 plots, the most valuable predictors were
potential solar radiation, a soils gradient related to available soil iron,
boron, and copper, and coarse-scale rock surface texture, although Geum radiatum
occurrences were difficult to predict at this scale. For 1-m2
subplots the best predictors were available soil cations, potential solar
radiation, the proportion of exposed bedrock, and vegetation height. Along
individual gradients response curves were often similar, but no two species were
predicted by identical sets of site parameters. Beyond current range limits,
existence of suitable habitat on 100-m2 plots was demonstrated for
Solidago spithamaea, supporting a view that the range limits of this species are
not necessarily set by availability of suitable habitat. Habitat-based models
have numerous management applications (such as to guide restoration and
reintroduction efforts as well as to direct searches for additional populations)
and provide a framework for future work on species-specific physiological
requirements. Wiser and Peet et al. 1998. Ecol. Appl.
Key words
Calamagrostis cainii; endemic; generalized additive
models; Geum radiatum; habitat characterization; Houstonia purpurea var. montana;
logistic regression; rare plants; rock outcrops; Solidago spithamaea; southern
Appalachian Mountains (USA).
Maximum
size–density relationship for constraining individual tree mortality functions
Y.
Yang
Forest
Biometrics Section, Forest Management Division, Land and Forest Service, Alberta
Sustainable Resource Development, 8th Floor, 9920-108 Street, Edmonton, Alta.,
Canada T5K 2M4
Stephen J. Titus
Department of Renewable Resources, 751 General Services Building, University of
Alberta, Edmonton, Alta., Canada T6G 2H1
Abstract
A maximum size–density relationship between
quadratic mean diameter and stand density was developed based on the
self-thinning concept. Several functions were compared first by fitting the
average size–density relationship and two equally good functions were selected
based on both fitting and prediction statistics. They were then refitted with a
defined loss function to derive the maximum size–density relationship. One
final function was chosen for constraining existing individual tree mortality
functions developed for major species in boreal mixedwood forests. It was found
that site quality did not affect this maximum size–density relationship. The
results also showed that separation of this relationship by species was not
possible. Yang and Titus 2002. For. Ecol. Manage. 168: 259-273.
Author Keywords
Tree mortality; Model constraint; Self-thinning;
Maximum size–density relationship; Boreal mixedwood
Yellow-Poplar: Characteristics and Management
Donald E. Beck, Lino Della-Bianca
Southeastern Forest Experiment Station, Asheville, North Carolina
Abstract
This reference tool and field guide for
foresters and other land managers includes a synthesis of information on the
characteristics of yellow-poplar with guidelines for managing the species. It is
based on research conducted by many individuals in
State and Federal forestry organizations and in universities throughout the
Eastern United States. This handbook describes distribution, uses, biological
and environmental features, regeneration methods, stand management
opportunities, and growth and yield estimates.
Beck and Della-Bianca 1981.
USDA Forest
Service
Agriculture
Handbook
Number 583.
Key
Words
Site, regeneration, stand management,
growth, yield, cultural practices, Liriodendron tulipifera.
Is This the Age of Intensive Management?
A Study of Loblolly Pine on Georgia’s Piedmont
Runsheng
Yin
Department of Forestry, Michigan State University, 126 Natural
Resources,East Lansing, MI 48824-1222
Roger A. Sedjo
Forest Economics and Policy Program, Resources for the Future,
Washington, DC.
Abstract
Using
data for loblolly pine from Georgia’s Piedmont, we find that, although the
transition from natural to artificial regeneration leads to increased and better
distributed stems, the control of competing vegetation results in a dramatic
boost to the growth rate from previous- to current-generation plantations. Our
results indicate that the marginal returns of forest management are increasing
rather than diminishing; the more intensive the management, the better its
economic performance. These findings suggest that intensive management
represents a major technical change and bodes well for the future of commercial
forestry in the South.
Yin and Sedjo 2001. J. For. 10:17 December.
Keywords
Economics;
herbicides; plantation forestry; silviculture
Density and the Growth of Even-Aged Stands
Boris Zeide
School
of Forest Resources, University of Arkansas at Monticello, Monticello, AR
71656-3468
Abstract
This
study develops a density-driven module and combines it with conventional growth
equations, making the resulting model applicable to managed stands. The
relationship between the diameter increment of an average tree and density
evolves from the analysis of amount of light coming to the unshaded (upper) part
of the crown, distribution of foliage along the stem, proportion of light
transmitted through the crown, probability of shading the lower part of the
crown, and other processes. The density module contains seven parameters, all of
which can be assessed from existing knowledge. One of the parameters quantifies
phenotypic adaptation, which mitigates competition stress. The entire model
starts and ends with basic measurable variables: number of trees per unit area
and their average diameter. The growth processes are evoked only to connect the
current and future values of stand variables. Zeide 2002. For.
Sci. 48 (4): 743–754.
Key Words
Adaptation,
foliage distribution, growth equations, process modeling.
Aboveground
biomass partitioning and leaf development of Chinese subtropical trees following
pruning
Bo
Zeng
Department of Plant Ecology, Utrecht University, P.O. Box 80084, 3508TB,
Utrecht, The Netherlands and Faculty of Life Science, Southwest China Normal
University, Beibei, Chongqing 400715, PR China
Abstract
To evaluate the effects of pruning on aboveground
biomass partitioning of trees and investigate the response of aboveground leaf
mass fractions of trees to pruning, a pruning experiment with four pruning
intensities (0, 20, 50, and 70%), two pruning seasons (spring and autumn), and
four subtropical Chinese tree species was carried out. Pruning treatments were
conducted in two successive years. In contrast to the prediction based on the
pipe model theory, pruned trees partitioned more of their newly produced
aboveground biomass to leaves and less to wood growth in most cases,
irrespective of species and pruning seasons. This partitioning pattern was
positively correlated with pruning intensity. Pruning reduced the aboveground
leaf mass fractions of trees instantaneously. However, due to the increased
partitioning of aboveground biomass to leaves following pruning, all pruned
trees reached the same aboveground leaf mass fractions as unpruned trees within
1 year after pruning (except for Pinus massoniana after the second
pruning). This unexpected biomass partitioning pattern might be attributed to
the reuse of open vascular channels in stem which were formerly connected to
removed branches and leaves. The increased partitioning of aboveground biomass
to leaves following pruning, would benefit pruned trees to alleviate negative
pruning effects and recover from the damage. Zeng 2003. For. Ecol. Manage. 173:
135-144.
Author Keywords
Aboveground biomass partitioning; Aboveground leaf
mass fraction; Functional equilibrium theory; Pipe model theory; Trees
Derivation,
Fitting, and Implication of a Compatible Stem Taper-Volume-Weight System for
Intensively Managed, Fast Growing Loblolly Pine
Yujia
Zhang, Bruce E. Borders, Robert L. Bailey
D.B.
Warnell School of Forest Resources, The University of Georgia, Athens, GA
30602-2152
Abstract
Geometry-oriented
methodology yielded a compatible taper-volume-weight system of models whose
parameters were estimated using data from intensively managed loblolly pine (Pinus
taeda L.) plantations in the lower coastal plain of Georgia. Two segments
(separated at a stem ratio of 0.60 of total height) depicted taper, volume, and
weight variations of the stems as well. The taper function defines stem taper as
a proportion of the diameter at breast height. The segmented volume equation was
derived from integration of the taper function along the stem, and it can be
readily transformed into a ratio volume equation. Likewise, the segmented weight
equation was obtained from integration of the volume function and a wood density
function. Data analysis showed that fertilization has significantly reduced
taper (inside and outside bark) on the upper segment and augmented stem
merchantable volume in this segment. However, unit-weight (green wood and bark,
green wood only, and dry wood only) was not significantly different between
fertilized and unfertilized trees, implying that annual fertilization did not
reduce the specific gravity very much. Finally, our analysis showed no
significant impacts of complete vegetation control on taper, volume or weight
characteristics. Zhang and Borders et al. 2002. For. Sci.
48(3):595–607.
Key
Words
Cross-equation
correlation of errors, constant form factor, variable form factor
Estimating
biomass and net primary production from forest inventory data: A case study of
China's Larix forests
Guangsheng
Zhou, Yuhui Wang, Yanling Jiang, Zhengyu Yang
Laboratory of Quantitative Vegetation Ecology, Institute of Botany, The Chinese
Academy of Sciences, Beijing 100093, PR China
Abstract
Forest inventory data (FID) are important resources
for understanding the dynamics of forest biomass, net primary production (NPP)
and carbon cycling at landscape and regional scales, especially for complying
with the Kyoto Protocol on greenhouse gas reduction and validating ecosystem
dynamic models from regional and global scales. FID-based biomass and NPP
estimation models for China's Larix forests are discussed in this paper.
The results indicated that the relationships between biomass (B) and its
volume (V), NPP and mean annual biomass increment (B/A) or
mean annual volume increment (V/A) can be expressed as hyperbola
curves for both natural and planted Larix forests. The relationship
between NPP and its biomass is not linear, which is not the same with the former
studies. These FID-based models take into account the change in the ratio of
forest biomass to volume with stand age and the effect of stand age on forest
NPP. The result also indicates that natural and planted forests should be
treated separately when biomass and NPP of forest are estimated based on FID.
Zhou and Wang et al. 2002. For. Ecol. Manage. 169: 149-157.
Author Keywords
Forest inventory data; Forest biomass; NPP of forest;
Larix forests; Model
A
Model for the Diameter-Height Distribution in an Uneven-Aged Beech Forest and a
Method to Assess the Fit of Such Models
Walter
Zucchini
Georg-August-Universität
Göttingen, Institute for Statistics and Econometrics
Matthias
Schmidt
Forest
Research Station of Lower Saxony
Klaus
v. Gadow
Georg-August-Universität
Göttingen, Institute for Forest Management and Yield Sciences
Abstract
This
paper illustrates the application of a mixture model to describe the bivariate
diameter-height distribution of trees growing in a pure, uneven-aged beech
forest. A mixture of two bivariate normal distributions is considered but the
methodology is applicable to mixtures of other distributions. The model was
fitted to diameter-height observations for 1242 beech trees in the protected
forest Dreyberg (Solling, Germany). A considerable advantage of the model, apart
from the fact that it happens to fit this large data set unusually well, is that
the individual parameters all have familiar interpretations. The bivariate
Johnson SBB
distribution
was also fitted to the data for the purpose of comparing the fits.
A second issue discussed in this paper
is concerned with the general question of assessing the fit of models for
bivariate data. We show how a device called “pseudoresidual” enables one to
investigate the fit of a bivariate model in new ways and in considerable detail.
Attractive features of pseudo-residuals include the fact that they are not
difficult to interpret; they can be computed using generally available
statistical software and, most important of all, they enable one to examine the
fit of a model by means of simple graphs.
Zucchini and Schimidt et al. 2001. Silva Fenn. 35: 169-183.
Keywords
Diameter-height
distribution, mixture models, bivariate normal distribution, SBB
distribution,
goodness-of-fit, pseudo-residuals, beech forest.
Plot Size Recommendations for Biomass Estimation in a Midwestern
Old-Growth Forest
Martin
A. Spetich
Southern Research Station, USDA Forest Service, Hot Springs, AR 71902
George R. Parker
Department of Forestry and Natural Resources, Purdue University, West
Lafayette, IN 47907
Abstract
We
examine the relationship between disturbance regime and plot size for woody
biomass estimation in a midwestern old-growth deciduous forest from 1926 to
1992. Analysis was done on the core 19.6 ac of a 50.1 ac forest in which
every tree 4 in. dbh and greater has been tagged and mapped since 1926. Five
windows of time are compared-1926, 1976, 1981, 1986 and 1992. The most efficient
plot sizes requiring measurement of the least total area range from 0.02 to 1.6
ac. A small plot
size was
recommended after grazing disturbance, and a large size was recommended when
mortality was high and acceptable error was low. Spetich and Parker 1998. North. J.
Appl. For. 15: 165-168.
Modeling Forest Fire Probabilities in the South Central
United States Using FIA Data
Yushun Zhai
Department of Forestry, Forest and Wildlife Research
Center, Mississippi State, MS 39762
Ian A. Munn
Forest Economics and Management, Department of Forestry,
Box 9681, Forest and Wildlife Research Center, Mississippi State, MS 39762
David L. Evans
Spatial Technologies, Department of Forestry, Forest and
Wildlife Research Center, Mississippi State, MS 39762
Abstract
Factors
influencing the probability of fire occurrence in the south central United
States were investigated using a geographic information system (GIS) and a
multinomial logit model. Forest Inventory and Analysis (FIA) data at the plot
level were merged with census data at the census-tract level to create a data
set containing demographic, geographic, and timber-related characteristics. A
multinomial logit model was employed to estimate the relationships between plot
characteristics and the probability of wildfires, prescribed fires, and fires of
unknown origins. Wildfires occurred more frequently on public forests than
industrial and nonindustrial private forests (NIPFs). The probability of
wildfire increased with proximity to urban areas and “built-up” areas of 4
ha or more in size. Wildfires occurred more frequently in younger stands and in
pine and mixed pine-hardwood types than in hardwood types. Prescribed fires
occurred more frequently on public and industrial forests than on NIPFs. The
probability of prescribed fires increased with proximity to roads, urban areas,
built-up areas of 4 ha or more, and on flatter terrain, but was inversely
related to population density. Fire was prescribed less frequently for
pole-sized stands than sawtimber size stands and more frequently for pine and
mixed pine-hardwood types than for hardwood types. Education levels and median
household incomes of the surrounding census tract had no significant effects on
the probability of any type of fire. Zhai and Munn et al. 2003. South. J. Appl. For.
27:11-17.
Key
Words
Fire
probability mapping, prescribed fire, wildfire, GIS.
Optical
Remote Sensing for Forest Area Estimation
Randolph
H. Wynne, Richard G. Oderwald
Department
of Forestry, College of Natural Resources, Virginia Polytechnic Institute and
State University, Blacksburg, VA 24061
Gregory
A. Reams
USDA
Forest Service, Southern Research Station, Asheville, North Carolina
John
A. Scrivani
Virginia
Department of Forestry, Charlottesville
Abstract
The
air photo dot-count method is now widely and successfully used for estimating
operational forest area in the USDA forest Inventory and Analysis (FIA) program.
Possible alternatives that would provide for more frequent updates, spectral
change detection, and maps of forest area include the AVHRR calibration-center
technique and various Landsat Thematic Mapper classification algorithms. Should
a switch from proven technology be advised, our general recommendation is to
conduct several pilot studies that would focus on developing or refining tools
and methodologies to allow objective, repeatable, and accurate forest area
estimation using multi-spectral earth resource satellite data.
Wynne and Oderwald et al. 2000.
J. For. 98:
31-36.
Modelling
the Number of Rings in Individual Logs of Norway Spruce
Laurent
Saint-André
INRA, Centre
de recherches forestie`res, Equipe de Recherches sur la Qualite´ des Bois,
54280 Champenoux, France
Jean-Christophe
Hervé
ENGREF, Dynamique des Syste`mes Forestiers,
54000 Nancy, France
Jean-Michel
Leban
INRA, Centre
de recherches forestie`res, Equipe de Recherches sur la Qualite´ des Bois,
54280 Champenoux, France
Abstract
In
timber production, there is a need to select the right log for a given
end-product. To achieve this objective, individual tree characteristics (total
height, diameter at breast height and age) and external measurements made on the
log shape were combined. In this study, three possible methods are analyzed to
assess the number of annual rings for a given Picea abies (L.) Karst. log
using modelling. The first method consists of finding a link between the number
of rings and the size, the taper and the location of the log in the tree. The
second one is based on the log location in the tree and the use of an height-age
growth model. The third involves the whorl location inside the log and the use
of an individual height-age growth model. The three methods are compared on the
basis of the amount of data required by each and error analysis. Saint-André
and Hervé. 2000. Scand. J. For.
Res. 15: 135–143.
Dimensionally
compatible volume and taper equations
Mahadev Sharma, Richard G. Oderwald
Department
of Forestry, Virginia Polytechnic Institute and State University, Blacksburg, VA
24061, USA
Abstract
A dimensional analysis approach was applied to derive analytically consistent
tree taper and volume equations. To achieve numerical consistency between the
taper and volume equations, parameters of the taper and the volume equations
were estimated simultaneously. Data from loblolly pine (Pinus taeda L.) trees
grown in natural stands in the Coastal Plain of North Carolina and the Coastal
Plain and Piedmont areas of Virginia were used to estimate the parameters. The
dimensionally compatible volume equation is shown to be a better equation for
estimation of the volume of loblolly pine trees grown in these sites and can be
applied for the estimation of total volume. The taper equation accurately
predicts tree diameters from butt to the tree tip. It can be used to predict the
diameter at any specified height and to predict height to any top diameter
limit. Sharma and Oderwald 2001.
Can. J. For. Res. 31: 797-803.
KeyWords Plus
Form
Phytomass
(live biomass) and carbon of Siberian forests
D.
Shepashenko
Moscow
State Forest University 141001, Mytishi, Moscow region Russia
A. Shvidenko, S. Nilsson
International Institute for Applied Systems Analysis A-2361, Laxenburg Austria
Abstract
The results of the
phytomass (live biomass) estimates inventory for the Siberian forests are
presented. These results are based on the following: (i) models estimating basic
phytomass fractions for eight main forest-forming species (pine, spruce, fir,
larch, Russian cedar, birch, aspen, oak); (ii) an ecoregional division of the
territory into 63 ecological regions; and (iii) data from the State Forest
Account (SFA) of 1993. The models are in the form of multidimensional regression
equations for the ratio Rfr =Mfr/GS, where Mfr
is the mass of a phytomass fraction in teragrams (Tg), and GS is (green)
growing stock in cubic meters (m3). The independent variables used
are age, site index and relative stocking of stands. The fractions evaluated are
wood and bark of the stems, bark, wood and bark of branches, foliage, stump and
roots, understorey and green forest floor. The final results are presented by 18
administrative units and three economic regions. The total phytomass of the
vegetation of forest ecosystems of the total forested areas in Siberia is
estimated to be 48 253.8 Tg of dry organic matter, of which 59.2% are stems,
18.4% stump and roots, 8.4% branches, 5.6% green forest cover, 3.4% foliage,
2.1% understorey and an additional 2.9% of the total phytomass is in the form of
shrubbery areas. Due to Russian forest terminology, forested areas, i.e. closed
forests, include forests generated by: (i) so-called main forest-forming species
combined in three groups (coniferous, hard-leaved deciduous and soft-leaved
deciduous); (ii) other species (rare, valuable and introduced species) with
small area; (iii) shrubbery areas, considered as forested areas for territories
where forests are not able to grow due to severe climatic conditions (zonal and
altitudinal tree lines). The average density of phytomass (as an average of the
total forested areas) is 4.04 kg of carbon (C) per square meter and varies from
2.0 kg C/m2 (in ecoregions of the forest tundra) to 5.7-5.9 kg C/m2
(in southern taiga and mixed broadleaved coniferous forests in the Far East).
The C dynamics over time that have been estimated based on official forest
inventory data for 1961-1993 reveal that during this period the Siberian forests
were, on average, a small source of C emissions (about 20 Tg C/year). For
`reconstructed' dynamics of the growing stock, which take into account
systematic errors in the forest inventory data, the Siberian forests were
estimated on average to sequester carbon (51 Tg C/year). Both approaches provide
the conclusion that during the 10 years between 1983 and 1992 the Siberian
forests have been a net source of atmospheric carbon (between 81 and 123 Tg
C/year). Shepashenko and Shvidenko et al. 1998 Biomass and Bioenergy.
14: 21-31.
Author
Keywords
Forest phytomass
estimates; Siberian forests; carbon dynamics
Incorporation
of indices of annual climatic variation into growth models for Pinus radiata
Peter
Snowdon, Tom Jovanovic, Trevor H. Booth
CSIRO Forestry and Forest Products, PO Box E4008, Kingston ACT 2604, Canberra,
Australia
Abstract
Data for Pinus
radiata D. Don grown in the Australian Capital Territory (ACT) are used to
show that annual indices of growth potential can be successfully incorporated
into Schumacher projection models of stand basal area growth. Significant
reductions in the error mean squares of the models can be obtained by including
a simple index such as annual rainfall, but best results were obtained by
incorporating estimates of photosynthesis simulated with a detailed
process-based model: BIOMASS. In the ACT it was sufficient to estimate the
growth index at a single location within the forest estate. Reductions in error
mean squares due to the incorporation of temporal variables were about twice as
large as those obtained by incorporating spatial variables such as geological
substrate, site index or indices of soil development. The gains due to the two
classes of variables were approximately additive. The new models improve the
descriptive power of the Schumacher model. Short-term predictions made with the
models should be more accurate than those obtained with the traditional model
and should be particularly useful for updating stand inventories. The new models
would be most applicable to regions where there is substantial variation in
climatic factors between growing seasons and where the object species is
responsive to those factors. A key result is that the temporal variation in the
growth indices need not be assessed at each sample plot used to calibrate the
model nor each inventory plot to which the model is applied. The temporal
variation is regional in nature; consequently, it can be characterised by
studies at a relatively few number of sites. This leads the way to new avenues
for forest modelling. Snowdon and Jovanovic et al. 1999. For. Ecol. Manage. 117:
187-197.
Author
Keywords
Basal area growth;
Schumacher model; Inventory; Rainfall; Process-based models; BIOMASS
Crown
Density and Growth Relationships Between Stands of Picea abies in Norway
Svein
Solberg, Bjørn Tveite
Norwegian
Forest Research Institute, Division of Forest Ecology, Høgskoleveien 12, N-
1432 Ås, Norway
Abstract
Relationships
between the crown density and growth of Norway spruce (Picea abies L.
Karst.) stands are presented, after removal of the effects of major natural
influences. Crown density was assessed annually from 1991 to 1996 on 569
monitoring plots comprising 40000 trees. Stand growth was determined from
measurements of diameter and height in 1991 and 1996. Various models explaining
mean crown density and annual growth of the stands as a function of natural
factors, such as age and site index, were compared. The influence of the natural
factors was then removed by recalculating crown density to residual values from
one preferred model, and by recalculating growth to relative values given as a
percentage of model predictions. Crown density and its residuals were positively
correlated to growth. These relationships were weak in terms of their ability to
explain variation (low R2). However, the various relationships
consistently indicated that approximately 1% change in crown density
corresponded to 1% change in growth. This relationship also included common
spatial variation over Norway: a large part of south-east Norway had unexplained
low crown density and unexplained low growth. Some other, smaller regional
consistencies were also found. The study supports the use of crown density
assessments and encourages the use of growth data in the search for major stress
factors responsible for present forest condition. Solberg and Tveite 2000.
Scand. J. For. Res. 15: 87–96.
Applicability
of the forest stand growth simulator PROGNAUS for the Austrian part of the
Bohemian Massif
Hubert
Sterba
Institut
für Waldwachstumsforschung, Universität für Bodenkultur, Peter Jordan Str. 82
A-1190 Vienna Austria
Robert
A. Monserud
Intermountain Research Station, USDA Forest Service, 1221 S. Main St. Moscow, ID
83843 USA
Abstract
Our objective is to
examine the applicability of the basal area increment model in the PROGNAUS
forest stand growth simulator using independent permanent plot data. The
simulator is designed to forecast the development of both pure even-aged and
mixed-species uneven-aged stands in Austria using distance-independent
individual tree methodology. The primary model is for the basal area increment (BAI),
which is predicted from size (diameter, crown ratio), competition (basal area of
larger trees, crown competition factor), and site descriptors. Because the model
must be able to simulate the development of both uneven- and even-aged stands,
site index and age are intentionally not used as predictors. Available for
testing is an independent data set of 22 permanent plots in mixed Scots pine (Pinus
sylvestris L.)-Norway spruce (Picea abies L.) stands in the Austrian
part of the Bohemian Massif, northeastern Austria. The validation plots were
remeasured for three 5-year periods between 1977 and 1992. The prediction
interval (95% confidence) for the basal area increment over the full 15-year
period was 62-157%, with a mean of 99% of the observed increment. A
plot-specific adjustment of the model's intercept using past increment did not
improve predictions for Norway spruce, but did improve predictions for Scots
pine. Thus, important site-specific variation not captured by the Scots pine
model can nevertheless be accounted for by using increment calibration. A time
trend towards increasing underestimation of the increment was detected in the
later growth periods of the validation data. This trend agrees with a frequently
reported increase in the site potential of central European stands, possibly
caused by changing weather conditions, nitrogen deposition, and abandoning of
litter raking. For future model development, as many growth periods as possible
should be used to parameterize increment models, although even this cannot
account for a long term change in the site potential. Sterba and Monserud 1997.
Ecol. Model. 98: 23-34.
Author
Keywords
Forest growth
prediction; Simulation modeling; Mixed stands; Austria; Norway spruce; Scots
pine
Prediction
of Stem Properties Based on Climate and Soil Factors in Naturally Regenerated Pinus
sylvestris Stands
Dag
Olsson Tegelmark
Högskolan
Dalarna, SE- 781 88 Borlänge, Sweden
Abstract
This
study aimed to investigate whether the number of stems per hectare with specific
quality attributes could be predicted at a site that has been naturally
regenerated with Scots pine (Pinus sylvestris L.) by evaluating site
factors only. Factors related to climate (geographic location, growing season,
temperature sum, humidity and frost frequency), soil properties (soil moisture,
soil texture and depth of soil and humus layers) and site index were used for
constructing models for predicting the number of stems per hectare that are
straight, have no spike knots, have a maximum of two branches > 10 mm in the
whorls, have no branch thicker than 15 mm and the thickest branch of which has
an angle that is not acute. Models were constructed by projection to latent
structures (PLS) modelling based on survey data from 24 stands in central and
southern Sweden. Cross-validated models using climate factors alone or a
combination of soil and climate factors explained 65-83% of the sum of squares
in the quality attributes. Tegelmark 1999. Scand.
J. For. Res. 14: 131–142.
Biomass
equations for sixty-five North American tree species
Michael
T. Ter-Mikaelian
Ontario
Forest Research Institute, 1235 Queen Street East, Sault Ste. Marie Ont. P6A 2E5
Canada
Michael
D. Korzukhin
Institute of Global Climate and Ecology Moscow, 107258 Russia
Abstract
The
paper presents a comprehensive review of the biomass equations for 65 North
American tree species. All equations are of the form M = aDb,
where M is the oven-dry weight of the biomass component of a tree (kg), D
is diameter at breast height (DBH) (cm), and a and b are
parameters. Equations for the following tree components were included in the
review: total aboveground biomass, stem wood, stem bark, total stem (wood and
bark), foliage, and branches (wood and bark). A total of 803 equations are
presented with the range of DBH values of the sample, sample size, coefficient
of determination R2, standard error of the estimate, fitting
method used to estimate the parameters a and b, correction factor
for a bias introduced by logarithmic transformation of the data, site index and
geographic location of the sampled stand(s), and a reference to the paper in
which the equation (or the data) was published. The review is a unique source of
equations that can be used to estimate tree biomass and/or to study the
variation of biomass components for a tree species. Ter-Mikaelian and Korzukhin
For. Ecol. Manage. 97: 1-24.
Author
Keywords
Aboveground biomass;
Stem wood biomass; Stem bark biomass; Foliage biomass; Branch biomass; Dry
weight
Growth
and yield functions for irrigated plantations of Eucalyptus camaldulensis in the
hot desert of India
V.P.
Tewari, Amit Verma, V.S. Kishan Kumar
Forest
Resource Management and Economics Division, Arid Forest Research Institute, P.O.
Krishi Mandi, NewPali Road, Jodhpur 342 005, India
Abstract
Eucalyptus
camaldulensis forms a major portion of irrigated plantations in the hot desert
of India and for e.ective management of these plantations, growth and yield
functions are necessary. This paper describes the development of height,
diameter and volume growth functions based on the analysis of the data collected
from the permanent sample plots laid out in the study area. The
Chapman–Richards equation could be used for the prediction of diameter growth
while the Schumacher model could be considered for predicting volume growth.
Some base-age variant and invariant site-index models, already reported in the
literature, were compared in terms of relative accuracy and it was found that
the Payandeh and Wang model performed the best among the four models tried.
Tewari and Verma et al. 2002. Bioresource
Technology 85: 137–146.
Keywords
Dominant
height; Diameter and volume growth; Site index; Eucalyptus camaldulensis;
Irrigated plantation; Hot desert; India
Modelling
the relationship between tree diameters and heights using SBB
distribution
V.
P. Tewari
Division
of Forest Resource Management and Economics, Arid Forest Research Institute,
Jodhpur 342 005, India
K.
V. Gadow
Institute of Forest Management and Yield Science, University of Goettingen,
Goettingen 37077, Germany
Abstract
The median regression
and the 5- and 95-percentile curves of the bivariate SBB
distribution were fitted to the diameter and height data of two forest stands.
One data set represented Acacia tortilis trees in a pure stand, the other
Fraxinus excelsior trees in a mixed forest. A median regression was
established between heights and diameters and this was taken as the basis for
calculating percentile lines which were used to set bounds on the heights. In
the two examples, the greatest variation in height occurred around the mean
diameter. The percentile lines obtained through the SBB
distribution function indicate that the variation in height for a given diameter
is less pronounced in the larger trees. Tewari and Gadow 1999. For. Ecol.
Manage. 119: 171-176.
Author
Keywords
SBB
distribution; Median regression; Diameter–height relationship; Fraxinus
excelsior; Acacia tortilis
Development
of top height model and site index curves for Azadirachta indica A. juss
V.
P. Tewari, V. S. Kishan Kumar
Forest Resource Management and Economics Division, Arid Forest Research
Institute, P.O. Krishi Mandi, New Pali Road, Jodhpur 342 005, India
Abstract
This paper describes
the development of top height model for stands of Azadirachta indica. The
algebraic difference form of the Chapman–Richards equation is first fitted to
the interval data of height–age data pairs resulting in an anamorphic system.
Polymorphic site index curves were also developed using Ek's extension of the
Chapman–Richards function. Secondly, some commonly used models were compared
for their goodness-of-fit and predictive ability in describing allometric
relationships between volume, diameter and age. It has been observed that, in
general, Chapman–Richards function may be used to model the relationships
between these growth parameters. Tewari and Kumar. 2002. For. Ecol. Manage. 165:
67-73.
Author
Keywords
Top height model;
Polymorphic site index curve; Neem; Hot semi-arid; India
Site
quality and stand structure in Pinus halepensis forests of north Greece
T.
Tsitsoni
Laboratory
of Sylviculture, Department of Forestry and Natural Environment, Aristotle
University of Thesssaloniki, 540 06, Thessaloniki, Greece
V.
Karagiannakidou
Institute
of Systematic Botany and Phytogeography, Department of Biology, Aristotle
University of Thessaloniki, 5430 06 Thessaloniki, Greece
Abstract
Pinus
halepensis forests depend
partly on the relatively adverse drought conditions prevailing in the area and
on human management through the centuries. A major and decisive factor for the
establishment and maintenance of these forest ecosystems is fire, which defines
their expansion. The degradation of these forests as a consequence of constant
pressure by natural and human-caused fires, grazing and clearance, has led to
the formation of scrub associations of the Cisto-Micromerietea. The
phytosociological study of the area and the analysis of the vegetation table
showed the existence of three site quality types I, II and III. The structure of
stands in these site types is mostly even-aged, occurring after a fire, in age
classes 10-20, 25-35, 40-50 and 60-80 years. The biggest mean diameter, total
basal area and mean dominant height of the overstorey, occurred on the more
soil-fertile site type I.
Tsitsoni and Karagiannakidou 2000. For. 73: 51 -- 64
A
height increment equation for young ponderosa pine plantations using
precipitation and soil factors
Fabian
C. C. Uzoh
Pacific Southwest Research Station, USDA Forest Service, 2400 Washington Avenue,
Redding, CA 96001, USA
Abstract
A height increment
equation was used to determine the effects of site quality and competing
herbaceous vegetation on the development of ponderosa pine seedlings (Pinus
ponderosa var. scopulorum Engelm.). Study areas were established in 36
plantations across northwest and west-central Montana on Champion International
Corporation's timberland (currently owned by Plum Creek Timber Company). Site
quality indices used in the equation were available water index (available water
capacity multiplied by the natural logarithm of annual precipitation) and site
index (SI) of the previous stand. Three-year height increment was modeled as a
function of tree size, vigor, and competition by using available water index (AWI)
and SI separately as site quality indicators in the same equation form.
Comparison of the two equations suggest that soil factors in combination with
precipitation data may be a useful alternative to traditional tree-based site
quality indices in predicting height increment of young stands where site index
is not known or is poorly estimated. Uzoh 2001. For. Ecol. Manage. 142: 193-203
Author
Keywords:
Height growth; Western
Montana; Site classification; Pinus ponderosa
Valentine HT
USDA
Forest Service, Northeastern Research Station, P.O. Box 640, Durham, NH
03824-0640, USA
Gregoire
TG
Yale
University, School of Forest and Environmental Studies, 360 Prospect street, New
Haven, CT 06511-2189, USA
Abstract
Numerical switches are employed to change the values of two exponents in a
variable-form model of bole taper. The taper of a bole is modeled, with respect
to height from the ground, by three connected geometric segments (i.e., a basal,
middle, and top segment). The numerical switches provide for either graded or
abrupt transition from the basal to the middle segment and from the middle to
the top segment. The height of the base of the crown was assumed to be the point
of transition between the middle and top segments. Crown height can be either
measured or estimated with a simple submodel that emerged from the taper model.
Compared with estimated crown height, the use of measured crown height improved
the precision of the taper model when fitted for Liquidambar styraciflua L., but
not Pinus elliottii Engelm., or Pinus ponderosa Dougl. ex P. & C. Laws. The
taper model also was fitted for Liriodendron tulipifera L., but crown height was
not available. Correlation among residuals within individual boles was accounted
for in the fitting procedure. The taper model proved to be reasonably precise
for all four species, and the parameters are easy to interpret.
Valentine and Greogoire 2001. Can. J. For. Res. 31: 1400-1409.
Key Words Plus
Incorporating Crown Ratio, Stem Volume, Equations, Prediction, Trees, Stand
Yield
Potential of Quercus robur Stands in Finland
Sauli
Valkonen, Piia Urpelainen, Anneli Virkki
Finnish
Forest Research Institute, Vantaa
Research Center, P.O. Box 18, FI-01301
Vantaa, Finland
Abstract
Yield
potential of common oak (Quercus robur L.) stands in Finland was examined
by estimating the site index value with a Swedish model of a sample of 23
existing stands in southern Finland, and studying its correlation with site
fertility and geographical location. Stand structure and yield parameters were
compared with those suggested by the Swedish management regimes to assess their
condition and potential for quality oak production. External wood quality and
sawlog volume were examined in sample tree data. The study stands scored high
site index values on the reference site index curves from southern Sweden. The
most fertile sites showed an average site index value of H100
= 28-30 m, and the common Oxalis-Myrtillus type H100 =
24-26 m. In the absence of thinning and pruning, the external quality of the
trees was poor. Defects had reduced the sawlog proportion on average by 40% from
the estimated maximum allowed by tree dimensions. Valkonen and Urpelainen
et al. 2002. Scand. J. For. Res. 17: 248–255.
Survival
and Early Development of Lodgepole Pine
M.
Varmola ; H. Salminen
Finnish
Forest Research Institute, Rovaniemi Research Station, P.O. Box 16, FIN-96301 Ro×aniemi,
Finland
R.
Rikala
Finnish
Forest Research Institute, Suonenjoki Research Station, Juntintie 40, FIN-77600
Suonenjoki, Finland
M.
Kerkelä
Sunit
Oy, Insinöörinkatu 8, FIN-50100 Mikkeli, Finland
Abstract
The
effect of site fertility, spacing and mode of regeneration on the survival and
stand development of lodgepole pine, Scots pine and Norway spruce was studied in
a series of experiments comprising 22 study areas in Finland. After 13-14 yrs,
lodgepole pine had a mean survival of 68% in planted and 61% in seeded plots,
while Norway spruce had the highest (92%) and Scots pine the second highest
survival (82%). The survival of planted lodgepole pine was better the wider the
spacing. Best survival was achieved on subdry and dry sites, both with planting
and with direct seeding. Dominant height was not affected by spacing, but both
basal area and volume at the age of 13-14 yrs were significantly higher the
denser the spacing. The average difference in the value of the estimated site
index H50 was slightly under 3 m for the superiority of
lodgepole compared with Scots pine. Seeding resulted in site indices almost as
high as those of lodgepole planting.