Treesearch

A two-dimensional nonhydrostatic atmospheric model is used to simulate the boundary-layer circulations that develop from multiple lines of extremely high surface temperatures. Numerical simulations are carried out to investigate the role of buoyancy and ambient crossflow effects in generating horizontal roll vortices in the vicinity of adjacent wildland fire perimeters. Numerical results suggest that the downdraft segments of buoyancy-generated horizontal roll vortices can be reinforced when multiple heating lines are present, with the degree of reinforcement dependent on the heating-line...

A cooperative area was established on the Glenwood Ranger District, Jefferson National Forest, to demonstrate the effectiveness of silvicultural treatments in minimizing gypsy effects to the public and forest resource professionals and provide additional research data on the effectiveness of the treatments versus direct insect treatments. The silvicultural treatments have been installed and the demonstration area is now available for tours.

The selection of forested natural areas for research and educational purposes is discussed. Five factors are important: sufficient size; representation of typical communities and sites; documented disturbance histories; acceptable current condition in terms of age, tree size, and successional stage; and administrative feasibility.

The study was conducted in an open field to detennine the optimum irradiance for establishment and growth of two oak species and two major associated woody species. Half-sib seedlings of black cherry (Prunus serotina Ehrh.), red maple (Acer rubrum L.), northern red oak (Quercus rubra L.) and black oak (Q. velutina Lam.) were grown for two years under shade-clotht ents. Eight shadet reatments( 94, 70, 57, 45, 37, 27, 20 and 8% of full sunlight) with three replications eachw ereu sed. Measurementsw ere made on seedlings harvested at the end of the first and second growing seasons. In the...

The potential for an evolutionary response to gypsy moth (Lymantna dispar L.) herbivory was investigated in red oak (Quercus rubra L.), a preferred host. Seedlings of nine open-pollinated families were grown in a greenhouse and experimentally defoliated by fourth instar larvae in the summer of 1991 to assay for intraspecific variation in resistance to and recovery from herbivory. Defoliation increased mortality and reduced growth differentially among the nine families. Family differences in plant size before defoliation explained much of the variation in mortality and growth following...

Methods to estimate present and future tree quality have been added to the OAKSIM and NE-TWIGS growth and yield simulators. These additions allow better estimates of stand value and thinning options.

Annual wildfire records (1926-77) from the national forests in states bordering the Ohio River (lllinois, Indiana, Kentucky, Missouri, Ohio, and West Virginia) were compared to climate records to assess relationships. Summaries of spring and fall fire seasons obtained for the Daniel Boone National Forest in Kentucky (1970-92) and for the State of Ohio (1969-84, including national forest lands) allowed for more detailed analysis. A wet spring followed by the onset of drought conditions, as measured by Palmer's Drought Severity Index (PDSI), was significantly correlated to the area burned by...

The Lymantria dispar multinucleocapsid nuclear polyhedrosis virus (LdMNPV) gene encoding vPK has been cloned and sequenced. LdMNPV vPK shows a 24% amino acid identity to the catalytic domains of the eucaryotic protein kinases nPKC from rabbits, HSPKCE from humans, APLPKCB from Aplysia californica, and dPKC98F from Drosophila melanogaster, and homology to several other protein kinases from yeasts, mice, and bovines. The homology suggests that vPK is a serine/threonine protein kinase as defined by Hanks et al. (S.K. Hanks, A.M. Quinn, and T. Hunter, Science 241:42-52, 1988). Temporal...

We have located, cloned, sequenced and characterized the ecdysteroid UDP-glucosyltransferase gene (egt) gene from the baculovirus Lymantria dispar multinucleocapsid nuclear polyhedrosis virus,(LdMNPV), which is specific for the gypsy moth (L. dispar). The egt gene from the related baculovirus Autographa californica multinucleocapsid nuclear polyhedrosis virus (AcMNPV) disrupts the hormonal balance of the host larva by galactosylating ecdysone, which prevents moulting. The location of the LdMNPV egt gene, determined by hybridization analysis using a cloned coding segment of the AcMNPV egt...

Urban forests are complex ecosystems created by the interaction of anthropogenic and natural processes. One key to better management of these systems is to understand urban forest structure and its relationship to forest functions. Through sampling and inventories, urban foresters often obtain structural information (e.g., numbers, location, size, and condition) on street- and/or park-tree populations to aid management. However, these public trees compose only a small portion of the urban forest.