Treesearch

Urban networks of air-quality monitors are often too widely spaced to identify sources of air pollutants, especially if they do not disperse far from emission sources. The objectives of this study were to test the use of moss bio-indicators to develop a fine-scale map of atmospherically-derived cadmium and to identify the sources of cadmium in a complex urban setting. We collected 346 samples of the moss Orthotrichum lyellii from deciduous trees in December, 2013 using a modified randomized grid-based sampling strategy across Portland, Oregon. We estimated a spatial linear model of moss...

We describe the use of linked land-use and forest sector models to simulate the effects of carbon offset sales on private forest owners' land-use and forest management decisions inwestern Oregon (USA). Our work focuses on forest management decisions rather than afforestation, allows full forest sector price adjustment to land-use changes, and incorporates time-dependent costs and restrictions of offset programs. The land-use model utilizes structure count data on some 21,000 plots spanning 30 years. The intertemporal optimizing forest sector model employs mill-level demand and FIA plot-leve...

Efforts to amend the Tongass National Forest Land Management Plan have necessitated the development of several management scenarios to assist with planning efforts. One scenario focuses on increasing the utilization of sawmill residues and low-grade material as feedstock for expanding biomass energy markets. The development of a biomass industry is viewed as a solution for a variety of problems in Alaska, from high heating fuel costs to a persistent lack of markets for mill and logging residue and low-grade logs since the last Alaska pulp mill closed in 1997. To support scenario development...

This report presents updated information on a 1981 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco var. menziesii ) plantation spacing trial at 33 years from planting. Stand statistics at the most recent measurement were compared for initial spacing of 1 through 6 meters and associated relative densities. There was no clear relationship of spacing to top height. Diameter, live crown ratio, and percent survival increased with spacing; basal area and relative density decreased with increase in spacing. Volume in trees ≥ 4 cm diameter was greatest at 2 m spacing, while utilizable volume...

We selected 66 sample trees from two thinning treatments, each of which was applied at three sites on the Siuslaw National Forest in Oregon. The first commercial thinnings, conducted in 1992 and 1993, had been designed to accelerate the development of large trees with large branches and other old-growth characteristics so as to improve habitat for bird species that depend on such characteristics. Our sample trees, removed in commercial thinnings from 2008 to 2010, were felled and bucked into long (woods-length) logs whose stems were measured in detail, with surface defects also measured...

Determining how the frequency, severity, and extent of forest fires are changing in response to changes in management and climate is a key concern in many regions where fire is an important natural disturbance. In the USA the only national-scale fire severity classification uses satellite image changedetection to produce maps for large (>400 ha) fires, and is generated by the Monitoring Trends in Burn Severity (MTBS) program. It is not clear how much forested area burns in smaller fires or whether ground-based fire severity estimates from a statistical sample of all forest lands might...

Backgrounds and aims Scotch broom is an N-fixing invasive species that has high potential to alter soil properties. We compared soil from areas of Scotch broom invasion with nearby areas that had no evidence of invasion to assess the influence of broom on soil P fractions and other chemical properties. Methods The study was conducted at two contrasting Douglas-fir sites in Oregon (OR) and Washington (WA), USA with broom invasion for 10 years. We used the Hedley sequential fractionation procedure to assess effects of Scotch broom invasion on P pools of varying bioavailability, and also...

The Aquatic Conservation Strategy (ACS) of the Northwest Forest Plan guides management of riparian and aquatic ecosystems on federal lands in western Oregon, western Washington, and northern California. We applied new scientific findings and tools to evaluate two potential options, A and B, for refining interim riparian reserves to meet ACS goals and likely challenges of climate change while supporting other management goals, including timber production. Interim riparian reserves are retained in late-successional reserves and other special land designations in the options. In lands...

Climatic effects on tree recruitment will be determined by the interactive effects of fecundity and seed predation. Evaluating how insect and vertebrate seed predators mediate tree reproductive responses to climate depends on long-term studies of seed production, development, and predation. In this study, our objectives were to (1) assess the effects of interannual climate variation on seed abortion rates, (2) assess the impact of seed density on predation rates, and (3) examine the degree to which density-dependent seed predation would amplify or dampen interannual variation in fecundity...

Natural resource policymakers and planners increasingly rely on regional and national-level spatial data describing projections of future housing growth, to anticipate development impacts on natural resources and identify policy and planning needs. Such projections have not always been well-grounded in demographic and other factors that influence population and thus housing growth. We develop an empirical model describing population change and housing growth in the rural Midwestern U.S., as a function of demographic transition, socioeconomic factors, and natural amenities. The empirical...