Treesearch

We summarize important landform, geological, and soil characteristics that affect the distribution of plants and animals at the MOFEP sites and that can potentially affect the observed response to MOFEP experimental treatments. The Missouri Ozark Forest Ecosystem Project (MOFEP) is located within the Current River Hills Subsection of the Ozark Highlands Section. The Ozark Highlands is an assemblage of nearly level to deeply dissected plateaus comprised primarily of Ordovician dolomites or sandstones. Soils are formed primarily in loess, hillslope sediments, and/ or residuum. Natural...

Carbon and sulfur transformations were studied in surface soils from plots in MOFEP sites from August 1993 to May 1996 and in plots in watersheds ofMOFEP sites 1, 3, and 4 from May 1995 to May 1996. Element pools measured included total carbon, total sulfur, sulfate, and organic sulfur. Transformations quantified included lignocellulose mineralization and organic sulfur production. Most parameters measured were similar compared by plots and sites, with large differences observed when compared by date. This baseline data, compared with post-treatment data, may help determine mechanisms...

Changes in global temperatures over the next century resulting from the greenhouse effect may have profound effects on the distribution and abundance of insect populations. One general hypothesis is the poleward shift of species distributions. We investigated potential range shifts for the spruce budworm, Choristoneura fumiferana, in the northeastern and north central United States using maps of historical outbreak areas, climatic variables, and the distribution of spruce-fir forests in a geographic information system. We developed canonical discriminant function models of the occurrence...

The need for integrated concepts, capable of satisfying natural and social scientists and supporting integrated research, motivates a conceptual framework for understanding the role of humans in ecosystems. The question is how to add humans to the ecological models used to understand urban ecosystems. The ecosystem concept can serve as the basis, but specific social attributes of humans and their institutions must be added. Learning and feedback between the human and natural components of urban ecosystems are key attributes of the integrated model. Parallels with familiar ecological...

This study empirically analyzes the evolution of national forest values in recent years. Four broad categories of forest values are distinguished: economic/utilitarian, life support, aesthetic, and moral/spiritual. A computerized content analysis procedure was developed to identify expressions of these four forest values related to the national forests. With this procedure, changes in the forest value systems of three groups—forestry professionals, mainstream environmentalists, and the general public—were tracked over time. Forest value systems were found to have shifted over the...

The abundance of twolined chestnut borer, Agrilus bilineatus (Weber), adults were sampled using sticky panels over a 6-year period in a mixed hardwood forest in West Virginia. Sixteen stands (average size 10.5 ha) were used in the study; eight of these were silviculturally thinned in 1989, the remainder were uncut. During 1990 and 1991, populations of gypsy moth, Lymantria dispar L., reached outbreak levels. Densities of A. bilineatus adults peaked in 1992, the year following the second defoliation year (1992), and were always greater in thinned than unthinned stands, however overstory...

Oak (Quercus spp.) decline is a malady related to the consequences of stress and successful attack of stressed trees by opportunistic (secondary) organisms (Wargo et al. 1983). It is a progressive process where trees decline in health for several years before they die. Houston (1981) developed a model of declines that is presented in Figure 1. So what is stress? It is pressure that brings ahout changes in a tree's physiology, form, or structure that predispose it to invasion by organisms that it ordinarily can resist. Stress can be biotic (defoliation by insects or fungi), abiotic (frost...

The effect of harvesting treatment, fencing, and species on the stem quality of oak (Quercus spp.) was evaluated in mixed-hardwood stands on the Allegheny Plateau in central Pennsylvania. The regeneration harvests included commercial clearcut that removed most stems ≥ 15 cm dbh and a clearcut with timber stand improvement (TSI) that removed all stems ≥ 2.5 cm dbh. Half of each area was fenced with 2.4-m-tall woven wire to prevent browsing by deer (Odocoileus virginianus) on the regeneration. After 15 years, the number of stems ≥ 2.5 cm dbh ranged from 4,865 to 8,416/ha and basal area...

Since 1868 or 1869, when it was introduced near Boston, the gypsy moth has been slowly expanding its range to include the entire northeastern United States and portions of Virginia, West Virginia, North Carolina, Ohio, and Michigan (Liebhold et al. 1992, 1996). It is inevitable that the gypsy moth will continue to spread south and west over the next century.

The wood turtle, Clemmys insculpta, is a long-lived, semi-aquatic, riverine species that inhabits forested regions of the northcentral and northeastern United States and adjacent regions of Canada. Many states list the wood turtle as "Endangered" or "Threatened" and it is now listed on Appendix II of the Convention on International Trade in Endrngered Species (CITES). In this paper, we examine the hypothesis that nesting areas are critical determinants of wood turtle occurrence in northern portions of its range. We measured six habitat variables at 334 nesting sites and used those data to...