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Evaluation of mixed-effects models for predicting Douglas-fir mortality

Creator:: Groom, Jeremiah D., Hann, David W., and Temesgen, Hailemariam
Abstract:: We examined the performance of several generalized linear fixed- and mixed-effects individual-tree mortality models for Douglas-fir stands in the Pacific Northwest. The mixed-effects models accounted for sampling and study design overdispersion. Inclusion of a random intercept term reduced model bias by 88% relative to the fixed-effects model; however, model discrimination...
Resource Type:: Article
Full Text:: predicting Douglas-fir mortality 1 2 3 4 Jeremiah D. Groom 1 5 Department of Forest Engineering

Sources of Variation in the Self-Thinning Boundary Line for Three Species with Varying Levels of Shade Tolerance

Creator:: Weiskittel, Aaron, Gould, Peter, and Temesgen, Hailemariam
Abstract:: The species self-thinning boundary line has been widely analyzed with a variety of statistical techniques. Most previous studies in the forestry literature have reported that the relationship does not differ across a range of stand and site factors, but these studies have primarily used statistical techniques that make model fitting...
Resource Type:: Article
Full Text:: . DE MONTIGNY, L., AND G. NIGH. 2007. Density frontiers for even-aged Douglas-fir and western hemlock

Regeneration imputation models for complex stands of southeastern British Columbia

Creator:: Hassani, Badre T., LeMay, Valerie, Marshall, Peter L., Temesgen, Hailemariam, and Zumrawi, Abdel-Azim
Abstract:: Two imputation techniques for predicting natural regeneration in complex stands prevalent in southeastern British Columbia (BC) were compared using data from the Interior Cedar-Hemlock moist warm subzone variant 2 (ICHmw2) in the vicinity of Nelson, BC. Imputation approaches offer advantages over other modeling approaches in that they provide estimates of...
Resource Type:: Article
Full Text:: , Valerie LeMay2, Peter L. Marshall3, H. Temesgen4 and Abdel-Azim Zumrawi5 Two imputation techniques for

Accuracy and suitability of selected sampling methods within conifer dominated riparian zones

Creator:: Marquardt, Theresa, Temesgen, Hailemariam, and Anderson, Paul D.
Abstract:: Sixteen sampling alternatives were examined for their performance to quantify selected attributes of overstory conifers in riparian areas of western Oregon. Each alternative was examined at eight headwater forest locations based on a 0.52 ha square stem maps. The alternatives were evaluated for selected stand attributes (trees per hectare, basal...
Resource Type:: Article
Full Text:: available at ScienceDirect Forest Ecology and Management journa l homepage: www.e lsev ier .com/ locate

Effects of height imputation strategies on stand volume estimation

Creator:: Garber, Sean M., Temesgen, Hailemariam, Monleon, Vicente J., and Harm, David W.
Abstract:: Subsampling and subsequent imputation of tree heights can improve the predictive performance of stand volume estimation but may also introduce biases. Using coastal Douglas-fir data from southwest Oregon, USA, the predictive performance of several height imputation strategies for estimating stand volume was evaluated. A subsample of 1-15 trees was randomly...
Resource Type:: Article
Full Text:: Douglas-fir data from southwest Oregon, USA, the predictive per- formance of several height imputation

A review of the challenges and opportunities in estimating above ground forest biomass using tree-level models

Creator:: Temesgen, Hailemariam, Affleck, David, Poudel, Krishna, Gray, Andrew, and Sessions, John
Abstract:: Accurate biomass measurements and analyses are critical components in quantifying carbon stocks and sequestration rates, assessing potential impacts due to climate change, locating bio-energy processing plants, and mapping and planning fuel treatments. To this end, biomass equations will remain a key component of future carbon measurements and estimation. As researchers...
Resource Type:: Article
Full Text:: relations in young Douglas-fir trees. Can J For Res. 14:900–904. Grigal DL, Kernick L. 1984. Generality

Tree crown ratio models for multi-species and multi-layered stands of southeastern British Columbia

Creator:: Temesgen, Hailemariam, LeMay, Valerie, and Mitchell, Stephen J.
Abstract:: The ratio of live crown length to tree height (crown ratio; CR) is often used as an important predictor variable for tree level growth equations, particularly for multi-species and multi-layered stands. Also, CR indicates tree vigour and can be an important habitat variable. Measurement of CR for each tree can...
Resource Type:: Article
Full Text:: conifers such as Douglas- fir (Pseudotsuga menziesii var. menziesii (Beissn.) Franco) and interior spruce

Regional Height-Diameter Equations for Maior Tree Species of Southwest Oregon

Creator:: Temesgen, Hailemariam, Hann, David W., and Monleon, Vincente J.
Abstract:: Selected tree height and diameter functions were evaluated for their predictive abilities for major tree species of southwest Oregon. Two sets of equations were evaluated. The first set included four base equations for estimating height as a function of individual tree diameter, and the remaining 16 equations enhanced the four...
Resource Type:: Article
Full Text:: of30 tree species were found on these 529 plots. The most common coniferous species was Douglas-fir

Mapping and imputing potential productivity of Pacific Northwest forests using climate variables

Creator:: Latta, Gregory, Temesgen, Hailemariam, and Barrett, Tara M.
Abstract:: Regional estimation of potential forest productivity is important to diverse applications, including biofuels supply, carbon sequestration, and projections of forest growth. Using PRISM (Parameter-elevation Regressions on Independent Slopes Model) climate and productivity data measured on a grid of 3356 Forest Inventory and Analysis plots in Oregon and Washington, we evaluated...
Resource Type:: Article
Full Text:: (MLR) to relate Douglas-fir productivity to geo- graphic and climatic variables have been completed in

Developing Biomass Equations for Western Hemlock and Red Alder Trees in Western Oregon Forests

Creator:: Poudel, Krishna P. and Temesgen, Hailemariam
Abstract:: Biomass estimates are required for reporting carbon, assessing feedstock availability, and assessing forest fire threat. We developed diameter- and height-based biomass equations for Western hemlock (Tsuga heterophylla (Raf.) Sarg.) and red alder (Alnus rubra Bong.) trees in Western Oregon. A system of component biomass equations was fitted simultaneously with a...
Resource Type:: Article
Full Text:: predict the proportion of AGB in different components for Douglas fir and lodgepole pine trees. These

ScholarsArchive@OSU

Evaluation of mixed-effects models for predicting Douglas-fir mortality

Sources of Variation in the Self-Thinning Boundary Line for Three Species with Varying Levels of Shade Tolerance

Regeneration imputation models for complex stands of southeastern British Columbia

Accuracy and suitability of selected sampling methods within conifer dominated riparian zones

Effects of height imputation strategies on stand volume estimation

A review of the challenges and opportunities in estimating above ground forest biomass using tree-level models

Tree crown ratio models for multi-species and multi-layered stands of southeastern British Columbia

Regional Height-Diameter Equations for Maior Tree Species of Southwest Oregon

Mapping and imputing potential productivity of Pacific Northwest forests using climate variables

Developing Biomass Equations for Western Hemlock and Red Alder Trees in Western Oregon Forests

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