Treesearch

Intensive research in several parts of Pennsylvania has demonstrated that dense herbaceous cover can inhibit the development of advance regeneration, and that advance regeneration often is lacking in Pennsylvania forests. The lack of quantitative statewide information on forest understory prompted a study to characterize advance regeneration and fern inhibition for Pennsylvania's forests.

There is a general lack of information that describes forest composition at the landscape level, e.g. for entire physiographic provinces. Studies in the ecological literature usually are local in scope and combining data from such studies is questionable due to different design methodology.

In 1991, a collaborative research project was initiated to create an ecological classification system for the Wayne National Forest of southeastern Ohio. The work focuses on the ecological land type (ELT) level of ecosystem classification. The most common ELTs are being identified and described using information from intensive field sampling and multivariate data analyses. The tentative ELT classification developed as a first approximation for Athens Unit (about one third of the entire forest) includes 17 ecological units defined by their slope position, steepness, aspect, and landform. A...

The species compositions of many upland hardwood forests in southeastern Ohio appear to be changing. Since the arrival of settlers, most of the mixed mesophytic forest has been cleared at least once as a result of timber cutting, burning, and agriculture. The compositions of the second- and third-growth forests are shifting toward a smaller component of oaks (Quercus spp.) and larger proportions of other species such as red maple (Acer rubrum). This study examines the development of existing young stands after clearcutttng on the Wayne National Forest. A chronosequence of 5- to 30-year old...

Competing vegetation and herbivory are thought to contribute to regeneration failure of northern red oak (Quercus rubra L.) in the Great Lakes Region.

The IMPLAN model for Pennsylvania was reviewed with respect to the industries processing the state's solid hardwood resources. Several sectors were found to be under represented in the standard sources of industrial activity. Further problems were attributed to the lack of distinction between hardwoods and softwoods in the national model. A further set of changes was made to update this set of industries.

The frequent scarcity of northern red oak (NRO) advance reproduction raises questions about its regeneration potential under prevailing stand conditions in eastern North America. In contrast, NRO plantations in France typically contain abundant advance reproduction. The purpose of this study was to document stand conditions in Pennsylvania (PA) and southwestern France (FR) that may be contributing to the difference in apparent regeneration potential. In each case, five mature stands or plantations were selected for study. The density of NRO advance reproduction was 2,500/ha In PA and...

The biochemical reactions within the soil are mediated by soil flora and fauna, and are catalyzed by enzymes. Therefore, enzymes play a significant role in nutrient cycling. Enzymes are specific for the type of chemical reactions in which they participate. Arylsulfatase is the enzyme that catalyzes the hydrolysis of an arylsulfate anion by fission of the oxygen-sulfur (0-5) bond. ∝-Glucosidase catalyzes the hydrolysis of ∝-D-glucopyranosides and is involved in the hydrolysis of maltose. β-Glucosidase catalyzes the hydrolysis of β-D-glucopyranosides and is involved in the hydrolysis of...

Twenty-eight plots were established in oak stands along the leading edge of gypsy moth migration into north-central West Virginia. Plots were arranged in a 3-chain square grid pattern in areas of varying aspect, percent slope, elevation, site index and species composition. Soft water, gypsy moth frass and leaf fragments generated by larval feeding were collected weekly from May 14 until July 30, 1992. Frass and leaf fragments were sorted and weighed. Water and frass samples were analyzed to determine concentrations of sodium, potassium, magnesium, calcium, hydrogen, phosphate and nitrate....

It is clear that our perspective, profession, society and approach to natural resource management has changed a lot over the last century and particularly over the last 30 years. We have adjusted to many changes and will be challenged to adjust to many more in the future. Understanding the global environmental perspective and expected trends should help us as we deal with the implications of change in our research and management positions. The trends for increased use of multidisciplinary approaches, concern for ecological management, global involvement, attention to risk assessment, and...