Treesearch

Bryophytes (mosses and liverworts) are often more responsive to water chemistry changes than are vascular plants. In this study, the relationships of bryophyte communities to stream pH and water chemistry were studied, using six streams on or near the Fernow Experimental Forest in Tucker County, West Virginia. Streams were surveyed with line transects using stratified random sampling. Bryophyte communities, based on species composition and structure, fell into three groups, corresponding to basic, moderately acidic, and very acidic stream water. For streams with sandstone beds, species...

A statistical report on the fourth forest inventory of New York 1991- 1994. Findings are displayed in 155 tables containing estimates of forest area numbers of trees wildlife habitat timber volume growth change and biomass. Data are presented at three levels; state, geographic unit, and county.

Describes the landscape ecosystems (ecoregions) of Michigan, Minnesota, and Wisconsin and includes maps of all three states. Regional descriptions include climate, bedrock geology, landforms, lakes and streams, soils, presettlement vegetation, natural disturbance, present vegetation and land use, rare biota, natural areas, public land managers, and conservation concerns.

Phis report presents an analysis of the results of the 1989 forest inventory of Pennsylvania as well as trends that habe occurred since the previous survey. Major topics include changes in forest land by ownership, forest type, and timberland component7 stand structure is charaterized by stand size, understory woody vegetation, dead trees, and changes in relative stocking; and harvesting by distribution d cut, species composition, and growth to rernovais ratios.

Four genotypic variants of Lymantria dispar multimucleocapsid nuclear polyhedrosis virus (LdMNPV) were used to investigate the generation of few polyhedra (FP) mutants during viral propagation in the L. dispar 652Y cell line. Titers of budded virus, the percentage of infected cells producting polyhedra, the amount of polyhedra produced per cell, the proportion of virus exhibiting an FP phenotype, virion occlusion characteristics, and changes in genomic DNA digestion profiles were investigated through five serial passages.

Depredation rates on artificial ground and shrub nests in large blocks of managed and remote reserved northern hardwood forests were studied in the White Mountain National Forest (WMNF) (303 930 ha) in New Hampshire, USA, from June to August 1991. Both types of nests were monitored by trip cameras that recorded depredations as eggs were removed. No differences in nest predation rates were found for either ground or shrub nests between managed and reserved forest blocks. Elevated nest predation rates are generally considered to be indicative of fragmented forest conditions; the results of...

The length of a randomly oriented ray emanating from an interior point of a planar region can be used to unbiasedly estimate the region's area and perimeter. Estimators and corresponding variance estimators under various selection strategies are presented.

The current interest among resource managers in ecosystem management necessitates a better understanding of the response of plant species diversity to forest management practices. This study attempted to assess the effects of one forest management practice—clear-cutting—on plant biodiversity in a mid-Appalachian hardwood forest by comparing species composition and diversity between two young (≈20 yr following clearcutting) and two "mature" (>70 yr following selective cutting) watersheds. Sampling was confined to the herbaceous layer (vascular plants ≤1-m in height) and woody overstory...

Changes in geographical ranges and spatial extent of outbreaks of pest species are likely consequences of climatic change. We investigated potential changes in spatial distribution of outbreaks of western spruce budworm, Choristoneura occidentalis Freeman, and gypsy moth, Lymantria dispar (L.), in Oregon and Pennsylvania, respectively, using maps of historical defoliation, climate, and forest type in a geographic information system. Maps of defoliation frequency at a resolution of 2 X 2 km were assembled from historical aerial survey data. Weather maps for mean monthly temperature maxima...

Cone Pond is one of the few acidic, clear-water ponds in the White Mountains of New Hampshire, a region dominated by high inputs of strong acids from atmospheric deposition and low base content of bedrock. Monitoring was conducted for 13 months to compare and contrast the acid-base chemistry of the terrestrial and aquatic portions of the watershed. Variations in Al concentration and speciation in drainage waters were correlated with changes in the supply of naturally occurring organic ligands. During the study period, the pond retained 28 % of Al inputs, including nearly half of the inputs...