Treesearch

During the course of this century the resilience of many ecosystems (their ability to adapt naturally) is likely to be exceeded by an unprecedented combination of change in climate, associated disturbances (e.g., flooding, drought, wildfire, insects, ocean acidification) and in other global change drivers (especially land-use change, pollution, and over-exploitation of resources), if greenhouse gas emissions and other changes continue at or above current rates (high confidence). By 2100, ecosystems will be exposed to atmospheric CO2 levels substantially higher than in the past 650,000...

Pollen and high-resolution charcoal records from three lakes were examined to reconstruct the vegetation and fire history of the Oregon Coast Range for the last 9000 years. The sites are located along a north to- south effective precipitation gradient and changes in vegetation and fire activity provided information on the nature of this gradient in the past. The relation of vegetation to climate change was examined at millennial timescales and the relation between fire and climate was examined on centennial timescales by comparing fire interval distribution and fire synchrony between...

The tasselled cap concept is extended to Moderate Resolution Imaging Spectroradiometer (MODIS) Nadir BRDF-Adjusted Reflectance (NBAR, MOD43) data. The transformation is based on a rigid rotation of principal component axes (PCAs) derived from a global sample spanning one full year of NBAR 16-day composites. To provide a standard for MODIS tasselled cap axes, we recommend an orientation in MODIS spectral band space as similar as possible to the orientation of the Landsat Thematic Mapper (TM) tasselled cap axes. To achieve this we first transformed our global sample of MODIS NBAR reflectance...

This study considers a carbon tax system as a policy tool for encouraging carbon sequestration through modification of management in existing forests and examines its welfare impacts and costs of the carbon sequestered. The simulated carbon tax leads to reduced harvest and increased carbon stock in the standing trees and understory biomass. Changes in the level of silvicultural investments differ by owner, depending on the nature of their initial inventory. In general, investment under the tax is concentrated in regimes that establish faster growing plantations. Average rotation age...

Exploratory modeling is an approach used when process and/or parameter uncertainties are such that modeling attempts at realistic prediction are not appropriate. Exploratory modeling makes use of computational experimentation to test how varying model scenarios drive model outcome. The goal of exploratory modeling is to better understand the system of interest through delineation of plausible boundaries, description of patterns within multidimensional model space, and to the extent possible, quantification of the likelihood of occurrence of different model outcomes. This study makes use of...

This study is the first broad investigation of therapeutic activities of hypogeous truffles and trufflelike fungi (Ascomycetes and Basidiomycetes) from North America. Twenty-two species from 12 families were evaluated in several biological assays for antimicrobial, antimalarial, antiinflammatory, antioxidant, antituberculosis, and anticancer activities. Biological screening results indicate that 1 species showed antimalarial activity, 11 species were active in antioxidant assay, 9 species were active in antiinflammatory assay, 9 species showed antituberculosis activity, and 2 species...

Two common sampling methodologies coupled with a simple statistical model were evaluated to determine the accuracy and precision of annual bole biomass production (BBP) and inter-annual variability estimates using this type of approach. We performed an uncertainty analysis using Monte Carlo methods in conjunction with radial growth core data from trees in three Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco)-dominated sites (young, mature, and old-growth) in the western Cascades of Oregon. A model based on the mean and standard deviation of annual radial growth from sampled trees was...

In many fire-prone forests in the United States, changes occurring in the last century have resulted in overstory structures, conifer densities, down woody structure, and fuel loads that deviate from those described historically. With these changes, forests are presumed to be unsustainable. Broad-scale treatments are proposed to reduce fuels and promote stand development on trajectories toward more sustainable structures. Yet little research to date has identified the effects of these treatments, especially in low-elevation dry ponderosa pine (Pinus ponderosa) and Douglas-fir (Pseudotsuga...

High-quality daily meteorological data at high spatial resolution are essential for a variety of hydrologic and ecological modeling applications that support environmental risk assessments and decisionmaking. This paper describes the development. application. and assessment of methods to construct daily high resolution (~50-m cell size) meteorological grids for the 2003 calendar year in the Upper South Santiam Watershed (USSW). a 500-km2 mountainous catchment draining the western slope of the Oregon Cascade Mountains. Elevations within the USSW ranged from 194 to 1650 m. Meteorological...

Industrial timber harvesting operations commonly employ heavy machinery and thus have the potential to inflict significant damage on soils, streams, and residual vegetation. Impacts associated with such operations have been especially troubling in many tropical countries, where mature trees often have large crowns capable of destroying other trees when they fall; soils remain wet for much of the year and are highly susceptible to significant compaction and erosion; loggers typically have little education, are poorly trained, and often must work and live in arduous, unhealthy conditions;...