Treesearch

Microarthropod densities within late-successional coniferous forests thinned 16-41 yr before sampling were compared with adjacent unthinned stands to identify longer term effects of thinning on this community. Soil and forest floor layers were sampled separately on eight paired sites. Within the forest floor oribatid, mesostigmatid, and to a marginal extent, prostigmatid mites, were reduced in thinned stands compared with unthinned stands. No differences were found for Collembola in the forest floor or for any mite suborder within the soil. Family level examination of mesostigmatid and...

In the Pacific Northwest, the process of conifer development after stand-replacing disturbance has important implications for many forest processes (e.g., carbon storage, nutrient cycling, and biodiversity). This paper examines conifer development in the Coast Range Province and Western Cascades Province of Oregon using repeat interpretation of historic aerial photographs from 1959 to 1997 to examine the canopy cover change of different life forms: shrubs, hardwood trees, and conifer trees. Ninety-four stands from the Western Cascades Province and 59 stands from the Coast Range Province...

The seasonal savannas (cerrados) of Central Brazil are characterized by a large diversity of evergreen and deciduous trees, which do not show a clear differentiation in terms of active rooting depth. Irrespective of the depth of the root system, expansion of new foliage in deciduous species occurs at the end of the dry season. In this study, we examined a suite of leaf traits related to C assimilation, water and nutrients (N, P) in five deciduous and six evergreen trees that were among the dominant families of cerrado vegetation. Maximum C02 assimilation on a mass basis (Amass) as significa...

Livestock grazing has been considered detrimental to wildlife habitat. Managed gazing programs, however, have the potential to maintain habitat diversity and quality. In cases in which single-species management predominates (sage-grouse [Centrocercus urophasianus] or elk [Cervus elaphus nelsoni] winter range), grazing systems specific to species' needs can be implemented. Managed livestock grazing can have 4 general impacts on vegetation: 1) alter the composition of the plant community, 2) increase the productivity of selected species, 3) increase the nutritive quality of the forage, and...

Soil properties and forest productivity can be affected by heavy equipment used for harvest and site preparation but these impacts vary greatly with site conditions and operational practices. We assessed the effects of ground-based logging on soil physical properties and subsequent Douglas-fir [Pseudotsuga menziesii (Mirb) Franco] growth on a highly productive site receiving vegetation control in coastal Washington. We also tested the effectiveness of tillage in maintaining or enhancing site productivity. On average, about half of the area of ground-based harvested plots was affected by...

Growing human populations inevitably lead to the conversion of some forestlands to more intensive developed uses. Resulting landscape changes can influence long-term timber production possibilities, and affect the quantity and quality of wildlife habitat, outdoor recreation and open spaces that contribute to people's quality of life. Anticipating the potential effects of forestland development can be important to formulating management and policy strategies that balance the multiple demands of society regarding land for development, resource production, and environmental protection....

Small-scale gasification plants that generate electrical energy from forest health thinnings may have the potential to deliver substantial amounts of electricity to the national grid. We evaluated the economic feasibility of two sizes of BioMax, a generator manufactured by the Community Power Corporation of Littleton, Colorado. At current avoided-cost electricity prices in Oregon, it would not be economical to operate a small-scale (100-kW) BioMax without a subsidy or tax credit, even if fuel were delivered to the plant at a forest landing at no cost. Given a tax credit, a 1,000-kW system...

The Larch Mountain salamander (Plethodon larselli Burns, 1954) is an endemic species in the Pacific northwestern United States facing threats related to habitat destruction. To facilitate development of conservation strategies, we used DNA sequences and RAPDs (random amplified polymorphic DNA) to examine differences among populations of this species. Phylogenetic analyses of cytochrome b revealed a clade of haplotypes from populations north of the Columbia River derived from a clade containing haplotypes from the river's southwestern region. Haplotypes from southeastern populations formed...

A plant species is defined as invasive if it is nonnative to the ecosystem under consideration, and if it causes or is likely to cause economic or environmental harm or harm to human health. Nonnative plant invasions are generally considered to have reached the Pacific Northwest in the mid-1800s with the arrival of European-American settlers. Invasive species such as sulfur cinquefoil, spotted knapweed, yellow starthistle, cheatgrass, and Japanese knotweed can displace native plants, disrupt ecosystems, affect biological diversity, increase soil erosion, reduce water quality, and change...

This paper examines what is needed to transform nature tourism to protected areas into ecotourism, having genuine social benefits and serving as a tool for sustainable community development. It draws on the case of the Ngorongoro Conservation Area, Tanzania's most visited protected area, and a multiple land use zone inhabited by the pastoral Maasai peoples. I argue that for ecotourism to promote sustainable development in communities that are its supposed beneficiaries, three fundamental conditions must be met. First, opportunities to capture the economic benefits of tourism must be...