Treesearch

Forest soils are entities within themselves, self-organized and highly resilient over time. The transfer of energy bound in carbon (C) molecules drives the organization and functions of this biological system (Fisher and Binkley, 2000; Paul and Clark, 1996). Photosynthetic organisms reduce atmospheric C and store energy from solar radiation in the formation of complex C molecules. This bound energy is transferred to mineral soil in the form of litterfall, root turnover, and root exudates supporting an intricate detrital trophic structure (Fisher, 1995). Much of the C moving through this...

Forests of the semiarid and arid zones of the interior western United States (US) are some of the most unique in North America. They occupy 11 to 34% of the landscape at mostly higher elevations (USDA Forest Service, 1981). These forests are characterized by a high diversity of flora, fauna, climates, elevations, soils, geology, hydrology, and productivity. Within the space of a few dozen kilometers, forests can change from desert shrublands to spruce and fir, the equivalent of going from northern Mexico to the Arctic. Because of the hydrologic cycle in the Interior West of the US, these...

Fragmentation of breeding habitat has been hypothesized as a cause of population declines in forest-nesting migratory birds. Negative correlations between the degree of fragmentation and bird density or fecundity at local or regional scales support the fragmentation hypothesis. Yet, in spite of reduced fecundity and densities in fragmented systems, many forest-nesting passerine species have increased in numbers over time. We hypothesized that range-wide population change in species for which habitat fragmentation negatively affects reproductive success should depend on the proportion of...

We empirically investigate the effect of the payment mechanism on contingent values by asking a willingness-to-pay question with one of three different payment mechanisms: individual contribution, contribution with provision point, and referendum. We find statistical evidence of more affirmative responses in the referendum treatment relative to the individual contribution treatment, some weak statistical evidence of more affirmative responses in the referendum treatment relative to the provision point treatment, and no statistical evidence of more affirmative responses in the provision...

This state-of-knowledge review about the effects of fire on air quality can assist land, fire, and air resource managers with fire and smoke planning, and their efforts to explain to others the science behind fire-related program policies and practices to improve air quality. Chapter topics include air quality regulations and fire; characterization of emissions from fire; the transport, dispersion, and modeling of fire emissions; atmospheric and plume chemistry; air quality impacts of fire; social consequences of air quality impacts; and recommendations for future research.

This paper adds to the limited knowledge of stand dynamics in pinyon-juniper woodlands by reporting on the changes in species composition, numbers of trees, arrangements of trees, and total height and volume in a stand from late 1938 to early 1991. This information should be helpful in managing pinyon-juniper woodlands to sustain their productivity and maintain their multiple-use values. The annual increase of 1.2 trees per acre does not reflect the massive invasion of trees suspected by many people.

Spatial aggregation of forest structure strongly regulates understory light and its spatial variation in longleaf pine (Pinus palustris Mill.) forest ecosystems. Previous studies have demonstrated that light availability strongly influences longleaf pine seedling growth. In this study, the relationship between spatial structure of a longleaf pine forest and spatial pattern of understory light availability were investigated by comparing three retention harvest treatments: singe-tree, small-group, large-group, and an uncut control. The harvests retained similar residaul basal area but the...

Data on hosts and geographic distribution of the juniper dwarf mistletoe, Arceuthobium oxycedri, are updated in light of changes in host nomenclature, political geography, and interpretation of reports and labels. Seventeen species of Juniperus, 3 Chamaecyparis, 5 Cupressus, and 1 Platycladus are reported as hosts. Infestations on several juniper hosts and all of its non-juniper hosts have resulted from introductions to areas within the natural range of the mistletoe. This dwarf mistletoe is reported from 31 countries across northern Africa, western Europe, the Balkans, Russia and other...

Nonnative invasive plants are altering ecosystems around the world with alarming speed. They outcompete native plants and ultimately change the composition and function of the ecosystems they invade. This poses a particular problem in wilderness and other natural areas that are set aside to maintain natural conditions. Wilderness managers are not only faced with the challenges of preventing and identifying new invasions, but they also must decide between allowing the unfettered existence and spread of invasive plants and using control strategies that can have unintended consequences. This...

The Interior West Forest Inventory and Analysis (IWFIA) Program of the USDA Forest Service, Rocky Mountain Research Station, as part of our National Forest System cooperative inventories, conducted a forest resource inventory on the Black Hills National Forest using a nationally standardized mapped-plot design (for more details see section "How was the inventory conducted?" page 11). This report presents the highlights of this 1999 periodic inventory using commonly requested variables and summaries. The data could be summarized in other ways for different purposes (see "For further...