Treesearch

Urban and community forests function to mitigate the environmental impacts of urbanization by moderating climate, conserving energy, carbon dioxide, and water, improving air quality, controlling rainfall runoff and flooding, lowering noise levels, harboring wildlife, and enhancing the attractiveness of cities. The economic value of these environmental benefits exceeds 3 billion dollars a year and substantial additional value can be inferred for the less tangible benefits associated with wildlife and aesthetics. These benefits may be partially offset by problems vegetation can pose such as...

Chemical control of a tall fescue sod (Festuca arundinacea Schreb.) using glyphosate and simazine improved early tree growth of black walnut (Juglans nigra L.) more than either deep ripping or irrigation on an upland old field site in southern Illinois. Growth of trees with irrigation and grass control was less than with grass control only; however, irrigation alone to maintain soil moisture levels above -0.5 atmospheres had no effect in the absence of grass control. Planting germinated seed at the intersection of the 30 inch deep ripping furrows was beneficial with grass control, but had...

Genomic expression of the Lymantriu dispar multinucleocapsid nuclear polyhedrosis virus (LdMNPV) was studied. Viral specific transcripts expressed in cell culture at various times from 2 through 72 h postinfection were identified and their genomic origins mapped through Northern analysis. Sixty-five distinct transcripts were identified in this analysis. Most viral transcripts were expressed late in infection, and originated from throughout the viral genome.

Saving energy has recently acquired new importance because of increased concern for dwindling fossil fuel supplies and for the problem of carbon dioxide contributions to global climate change. Many studies have indicated that windbreaks have the ability to save energy for heating buildings. Suggested savings have ranged up 40 percent; though more commonly savings of between 10 and 25 percent arc indicated (DeWalle and Heisler 1988).Questions remain as to how to best design windbreak plantings for different climates and building structures.

Urban land in the United States currently occupies about 69 million acres with an estimated average crown cover of 28% and an estimated tree biomass of about 27 tons/acre. This structure suggests that the current total urban forest carbon storage in the United States is approximately 800 million tons with an estimated annual net carbon storage of around 6.5 million tons. Besides directly storing carbon, urban trees also reduce carbon dioxide (CO2) emissions by cooling ambient air and allowing residents to minimize annual heating and cooling. Approaches for understanding urban trees and CO2...

Monterey pine street trees within Carmel, California and its immediate vicinity, as well as forest-grown Monterey pine within adjacent natural stands, were sampled with regard to visual stress characteristics, and various environmental and biological variables. Two stress indices were computed, one hypothesized before data collection was based on relative foliage retention and color; the other was derived through principal component analysis of 10 visual stress characteristics. Both indices were highly correlated (r = 0·89). The more closed and generally denser forest stands led to...

A procedure for constructing confidence intervals and testing hypothese from a single trial or observation is reviewed. The procedure requires a prior, fixed estimate or guess of the outcome of an experiment or sampling. Two examples of applications are described: a confidence interval is constructed for the expected outcome of a systematic sampling of a forested tract, and a hypothesis is tested in connection with a watershed experiment. Potential misuses of the procedure also are discussed.

A hardwood resources assessment was completed for the Sierra Economic Development District in the north central Sierra Nevada. The assessment included the development of a tree grading system for the major hardwood species in the area, an inventory of the hardwood resources, and recommendations for hardwood management. Hardwood volumes of total wood available for utilization per acre were found to be low for stands classified in the Blue oak-Interior live oak association, moderate in the Black oak - Canyon live oak association, and high in the Madrone association. The volumes by species...

The Northern Goshawk (Accipiter gentilis) is a rare to uncommon woodland raptor in Pennsylvania. Although it is primarily a boreal species, the goshawk nests in Northern Hardwoods and Appalachian oak forests along the southern margin of its range in Pennsylvania. This study compared the nesting habitat of goshawks in Appalachian oak and Northern Hardwoods forests in Pennsylvania during the 1989-90 field seasons.

Chestnut oak (Quercus prinus L.) and red oak (Quercus rubra L.) seedlings were grown for two seasons under two nutrient regimes: fertilizer + (NPK) and fertilizer - (No NPK). Beginning two weeks after budbreak, water was withheld for 10 weeks during the second growing season. Leaf water potentials, gas exchange measurements and growth measurements were made on a subset of plants on alternate weeks (5 sample weeks).