Treesearch

The United States is expected to add around 120 million, an additional 40 percent, to its population in the next 50 years and personal incomes are generally projected to rise. This will inevitably intensify land use pressures. Between 1992 and 1997, USDA's National Resource Inventory estimated that 2.2 million acres of rural land were developed each year, with forest land being the largest source. Sustainability options for agriculture, forestry, residential communities, biodiversity, and employment are worth exploring. Forest and aquatic ecosystems are shaped by interactions that cross...

Over the years, scientists have published many results from studies about the importance of habitat such as woody debris for supporting fish populations. They also have learned much about the ways in which land management activities can enhance or degrade such habitat. They know much less, however, about the food half of this foo-and-shelter equation.In the nutrient-poor streams of Alaska, the mystery of how those streams are so productive of salmon is beginning to be solved by investigating the nutritional links between organisms and among ecosystems—many of which are nearly invisible....

Settlement of the Pacific Northwest by immigrants from the Eastern United States changed the composition of lowland landscapes from dominance by forests and prairie to dominance by cities, suburbs, agriculture, and transportation infrastructure. Historical disturbance regimes imposed by nature and by indigenous people were disrupted. In the uplands, timber management activities replaced natural disturbance regimes, often with simplifying effects on ecosystems. People intentionally and unintentionally imported exotic species of plants and animals. Simplification of ecosystems and introductio...

When Mount St. Helens blew in 1980 it took with it some old ideas that have surprised scientists over the intervening 20 years. Traditional wisdom about ecological succession, survival, and disturbance regimes was moved aside by discoveries of the power of time and chance as environmental agents. Theories about recovery and restoration also have been revised in the wake of many unsuccessful attempts to return the area to its former state. For it seems the nature of living legacies left behind after disturbance plays a far more important role than previously understood. This finding also...

Seasonal patterns of carbohydrate concentration in coarse and fine roots, stem or bole, and foliage of ponderosa pine (Pinus ponderosa Laws) were described across five treeage classes from seedlings to mature trees at an atmospherically clean site. Relative to all other tree-age classes, seedlings exhibited greater tissue carbohydrate concentration in stems and foliage, and greater shifts in the time at which maximum and minimum carbohydrate concentration occurred. To determine the effect of environmental stressors on tissue carbohydrate concentration, two tree-age classes (40-year-old and...

Plant physiological models are generally parameterized from many different sources of data, including chamber experiments and plantations, from seedlings to mature trees. We obtained a comprehensive data set for a natural stand of ponderosa pine (Pinus ponderosa Laws.) and used these data to parameterize the physiologically based model, TREGRO. Representative trees of each of five tree age classes were selected based on population means of morphological, physiological, and nearest neighbor attributes. Differences in key physiological attributes (gas exchange, needle chemistry, elongation...

Our objectives were to examine the relationship between contemporary vegetation and surface soil phytolith assemblages, and use phytoliths and δ13C of soil organic matter (SOM) to explore forest-grassland vegetation dynamics. We established plots within three canopy types (open, old-growth, and dense young pine) with different grass species compositions in a Pinus ponderosa forest in northern Arizona and collected vegetation data and surface (0-2 cm) and subsurface (2-7 cm) mineral soil samples. Surface soil phytolith assemblages strongly reflected vegetation at the site scale. Local...

Phytolith analysis could play an important role in understanding vegetation dynamics in southwestern ponderosa pine (Pinus ponderosa) forests, which have been dramatically altered by fire suppression and other factors. My objectives were to develop a phytolith reference collection and classification system for a ponderosa pine-bunchgrass community found near Flagstaff, Arizona.

We surveyed the 22 largest sites dominated by Oregon white oaks on the Fort Lewis Military Reservation, Washington, to determine small-mammal community structure and population abundances. Study areas were in the Puget Trough physiographic province and western hemlock vegetation zone. Most oak communities were ecotonal between prairie and Douglas-fir forest. Small mammals were sampled at each site using paired lines of live traps for four nights, July and August 1999. In order of decreasing abundance, the deer mouse, vagrant shrew, Trowbridge's shrew, and creeping vole were the most...

Outdoor recreation participation and consumption by Alaska residents are analyzed and projected to 2020. Both the rate of participation and the intensity of participation in nearly all outdoor recreation activities are higher among Alaskans than for residents of other states. Projections based on economic and demographic trends indicate that current patterns are likely to continue, and demand for outdoor recreation among Alaskans will keep pace with projected increases in population. Activities with the highest participation rates per capita are viewing birds and wildlife, scenic driving,...