Tipton J.,Colorado State University |
Opsomer J.,Colorado State University |
Moisen G.,Forestry science Laboratory
Remote Sensing of Environment | Year: 2013
Post-stratification is commonly used to improve the precision of survey estimates. In traditional post-stratification methods, the stratification variable must be known at the population level. When suitable covariates are available at the population level, an alternative approach consists of fitting a model on the covariates, making predictions for the population and then stratifying on these predicted values. This method is called Endogenous Post-Stratification Estimation (EPSE) and it is well suited for applications using remote sensing data. In this article, we investigate the performance of EPSE in a realistic setting using data from the United States Forest Service Forest Inventory Analysis and Landsat Enhanced Thematic Mapper Plus. This article has three specific objectives: first, to evaluate the statistical properties of EPSE when using linear regression, spline regression, and the machine learning tool Random Forest to predict tree canopy cover using remote sensing and Geographic Information System data; second, to investigate the effect on the EPSE variance estimator using estimated stratum boundaries instead of fixed stratum boundaries; and third, to investigate the effect on the EPSE variance estimator when optimizing the stratum boundaries to minimize the variance estimate. The main findings of this article are that the EPSE variance estimator performs well using Random Forests, but can underestimate the true variance if an optimization is performed on the stratum boundaries in an attempt to minimize the variance estimate. This result supports the use of the EPSE estimator using remote sensing data in cases where there is no optimization on the variance estimator. 2013 Elsevier Inc.
PubMed | Forestry science Laboratory, U.S. Department of Agriculture and Texas A&M University
Type: Journal Article | Journal: Lipids | Year: 2016
Lipids from the paracloacal glands of adult Chinese alligators (Alligator sinensis) were analyzed by gas chromatography/mass spectrometry. Acetates, aliphatic alcohols, free fatty acids and waxes consisting primarily of hexadecanoates were indicated in the secretions of males and females. Cholesterol, a diterpene hydrocarbon, and a diterpene ketone were detected in secretions of males but not in those of females. Lipids identified in the paracloacal secretions ofA. sinensis are compared with those reported from the American alligator and other crocodilians.
Brantley S.L.,University of New Mexico |
Ford P.L.,Forestry science Laboratory
USDA Forest Service - General Technical Report RMRS-GTR | Year: 2012
Recent research and species distribution modeling predict large changes in the distributions of species and vegetation types in the western interior of the United States in response to climate change. This volume reviews existing climate models that predict species and vegetation changes in the western United States, and it synthesizes knowledge about climate change impacts on the native fauna and flora of grasslands, shrublands and deserts of the interior American West. Species' responses will depend not only on their physiological tolerances but also on their phenology, establishment properties, biotic interactions, and capacity to evolve and migrate. The volume is divided into eight chapters that cover the topics of carbon mitigation and adaptation. Current and likely responses of species and habitats to climate change are examined in relation to taxonomic group and ecoregion and with regard to other disturbances. The volume ends with a review of management decision support needs and tools for assessing vulnerability of natural resources and conserving and restoring ecosystems that are or may be impacted by climate change. © Larry Jones.
Harrington T.B.,Forestry science Laboratory |
Anderson H.W.,Forestry science Laboratory
USDA Forest Service - Research Paper PNW-RP | Year: 2016
Amendment of soil nutrients through fertilization is used to increase wood production of forest stands. Subsequent allocation of growth to individual trees and the resulting increase in stand volume and value, however, depend on stand density at the time of treatment. Our primary research question was: To what extent can volume growth per acre in precommercially thinned or nonthinned portions of a poor-site, 30-year-old coast Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco var. menziesii) plantation be increased by a single application of 200 or 400 lb nitrogen (N)/acre as urea? Each fertilizer treatment was replicated on three 0.2-acre plots in thinned and nonthinned stands located in Rocky Brook drainage on the Olympic Peninsula in Washington. All trees in the interior 0.1-acre plots with a diameter at breast height (d.b.h.) of 1.6 inches and larger were measured for stem diameter, and a subset of trees was measured for total height and height to live crown. We anticipated that poor site quality, prolonged overstocking, and a subsequent severe thinning would influence the responses we observed. In the 20 years after fertilization, net growth in total stem volume on fertilized plots averaged 50 percent greater than on nonfertilized plots in the previously thinned stand and 31 percent greater in the nonthinned stand. In both stands, mortality losses were relatively small, averaging 1 to 15 percent of gross annual growth. Diameter growth of the 100 largest trees per acre was improved by both thinning and fertilization. Present net value (PNV) (in 2014 dollars) at the hypothetical final harvest of the thinned stand was increased by delaying the harvest from 10 years (age 40) until 20 years after fertilization (age 50), and by fertilization, although differences between the 200 and 400 lb N/acre treatments were not significant. Present net value of the nonthinned stand also was increased by delaying final harvest until 20 years after fertilization; however, PNV did not differ significantly among the 0, 200, and 400 lb N/acre treatments, indicating no financial benefit from fertilizing this nonthinned stand. The 90-percent confidence interval for PNV of nonfertilized plots in the thinned stand ($919 ± $278 per acre) did not overlap with that of nonfertilized plots in the nonthinned stand ($2,639 ± $498 per acre), suggesting that the thinning prescription reduced the economic value of this overstocked stand at Rocky Brook. Clearly, the severe thinning at age 30 reduced stocking to the point at which the stand was slow to reoccupy this poor quality site. © 2016, USDA Forest Service. All rights reserved.
Hemstrom M.A.,Forestry science Laboratory |
Hemstrom M.A.,Oregon State University
USDA Forest Service - General Technical Report PNW-GTR | Year: 2012
The Integrated Landscape Assessment Project (ILAP) uses spatial vegetation data and state and transition models (STM) to forecast future vegetation conditions and the interacting effects of natural disturbances and management activities. Results from ILAP will help land managers, planners, and policymakers evaluate management strategies that reduce fire risk, improve wildlife habitat, and benefit rural communities. This case study illustrates the methodology for modeling timber volume, biomass estimates, and the forest carbon over time with the output of STM simulations. It presents how the Forest Inventory and Analysis data were applied to assist the interpretation of STM simulation results and derives useful information to the public. The method was applied in the central Washington study area to project the timber production, biomass supply potential, and aboveground carbon stock for two alternative management scenarios.
Harrington T.B.,Forestry science Laboratory
USDA Forest Service - Research Paper PNW-RP | Year: 2011
Greenhouse pot studies were conducted to quantify the competitive abilities of three native perennial grass species to inhibit development of Scotch broom (Cytisus scoparius (L.) Link) seedlings: spike bentgrass (Agrostis exarata Trin.), blue wildrye (Elymus glaucus Buckley), and western fescue (Festuca occidentalis Hook.). In single-species stands (1) soil water content decreased with increasing grass density, (2) soil water depletion per plant differed among species as ratios of 2.4:1.3:1 for bentgrass, fescue, and wildrye, respectively, and (3) average percentage of ground cover per plant was ranked by species as bentgrass (14 percent), wildrye (8 percent), broom (8 percent), and fescue (5 percent). Regression models predicted 90, 85, and 72 percent reductions in average biomass per plant of broom when grown with approximately 250 plants/m 2 of bentgrass, wildrye, and fescue, respectively. Bentgrass and wildrye were more competitive than fescue because of their early-season depletion of soil water and rapid development of cover.
Peter D.H.,Forestry science Laboratory |
Harrington T.B.,Forestry science Laboratory
USDA Forest Service - Research Paper PNW-RP | Year: 2012
To increase timber production and manage other forest resource values, some land managers have undertaken logging debris and vegetation control treatments after forest harvest. We explored the roles of clearcutting on plant community composition and structure at three sites where logging debris was dispersed, piled, or removed and vegetation was annually treated or not treated with herbicides for 5 years. Without vegetation control, a competitive relation was identified between exotic and native ruderal (i.e., disturbance-associated) species. When exotic ruderal cover changed by 4 percent, native ruderal cover changed by 10 percent in the opposite direction. This relation was independent of site, but site was important in determining the overall dominance of ruderals. Five annual vegetation control treatments increased Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) growth, but decreased richness and cover of other species at the rate of one species per 10 percent reduction in cover. Debris treatment effects were small and found on only one site.
Hanley T.A.,Forestry science Laboratory |
Barnard J.C.,Forestry science Laboratory
USDA Forest Service - Research Paper PNW-RP | Year: 2014
Variation in nutritional quality of natural forages for black-tailed deer (Odocoileus hemionus) was studied in summer and winter in southeast Alaska. Freeze-dried samples of 17 summer forages collected in early July and 10 winter forages collected in February from three replicate sites each of shady forest understory and open, sunny habitat were analyzed and compared for their concentrations of digestible protein, digestible dry matter, and digestible energy. Data from each forage, ranging from forb and shrub leaves to woody twigs, were analyzed separately in a single-factor analysis of variance experimental design. Only five to seven of the summer forages differed significantly (P <0.05) in values from sun and shade treatments: digestible protein was lower while digestible dry matter and digestible energy were higher in sun-grown than shade-grown forages. Differences in winter forages were fewer and inconsistent. However, despite general trends in patterns across all forages, variation both among and within forages was high at all scales of sampling: subsamples within a site, replicate sites of habitat types, and habitat types. Light intensity plays a major role in determining plant chemistry of some species, but the high degree of variation in plant response makes underlying patterns of variation especially important. © 2014, USDA Forest Service. All rights reserved.
Root H.T.,Oregon State University |
McCune B.,Oregon State University |
Jovan S.,Forestry science Laboratory
Bryologist | Year: 2014
Because of their unique physiology, lichen communities are highly sensitive to climatic conditions, making them ideal bioindicators for climate change. Southeast and south-central Alaska host diverse and abundant lichen communities and are faced with a more rapidly changing climate than many more southerly latitudes. We develop sensitive lichen-based indicators for tracking the effects of climate change in south-central and southeast Alaska. Using 196 plots, we model community composition and 12 individual species abundances in relation to synthetic climate variables. Both types of lichen indicator are closely related to the climate variable describing a transition from warm, wet oceanic climates to cooler, drier suboceanic climates. Lichen communities and individual species exhibited thresholds associated with average December minimum temperatures between -10.2 and -7.8°C and annual precipitation between 106 and 172 cm, suggesting rapid turnover with relatively small changes within these ranges. These climate conditions occur close to the coast in northern portions of the region and further inland in southeast Alaska. Because lichen communities in the threshold region may be most sensitive to a changing future climate, they should be targeted for monitoring efforts. © The American Bryological and Lichenological Society, Inc.
PubMed | Forestry science Laboratory
Type: Journal Article | Journal: Journal of chemical ecology | Year: 2013
Several hymenopterous parasites ofScolytus multistriatus are attracted to components of its aggregation pheromone, multilure.Cheiropachus colon, Entedon leucogramma, Dendrosoter protuberans, Spathius benefactor, andCerocephala eccoptogastri are attracted in various degrees to multilure, its components (multistriatin, 4-methyl-3-heptanol, and cubebene), and component combinations.C. colon was trapped in greatest numbers, yet was usually less numerous thanE. leucogramma andD. protuberans in the study area. Impact of traps onC. colon may conceivably be reduced by multistriatin content in baits and/or by withholding traps untilS. multistriatus flight begins.