Treesearch

Tree survival depends on the chemistry of phenolic compounds, a broad class of chemicals characterized by a hydroxylated benzene ring. In trees, phenolics occur frequently as polymers, acids, or glycosylated esters and perform diverse functions. For example, lignin, a phenylpropane heteropolymer, provides structural strength to wood. The induced production of phenols is a common response to injury and infection for both woody and nonwoody plants. Phenolics also deter herbivores from feeding on leaves, slow the spread of pathogens in roots and bark, confer some measure of durability to...

An environmentally responsive, mechanistic regeneration simulator should simulate important ecological relationships and disturbance effects. Development of such a regeneration simulator is complex because of the many attributes that characterize reproductive strategies and the importance of forest history and disturbance in determining the composition of the next forest. We are constructing a model of tree regeneration based on the requirements of different tree species and the potential pathways by which available species might regenerate. This rule-based Mechanistic Origination Model...

More than 1 million U.S. workers in some 45,000 firms are employed in the lumber, wood products, furniture, and fixture industries. Wood household and office furniture (SIC 251 and 252) are the largest manufacturing segments, adding $13.851 billion per year to raw product value. During the 1980s, U.S. furniture manufacturers lost sizeable market share to Pacific Rim countries. To improve their performance in increasingly global markets, U.S. manufacturers must have a clear understanding of how to assess their competitive position and how to affect its strategic determinants. This paper...

The life cycle of the Lymantria dispar nuclear polyhedrosis virus (LdMNPV) was characterized through analysis of budded virus (BV) release, the temporal formation of polyhedra, the temporal transcription pattern of representative early, late, and hyper-expressed late genes, and the onset of DNA replication in the Ld652Y cell line. Transcripts from the LdMNPV immediate early gene G22 were detected 4 h post infection (h p.i.). The late and hyper-expressed late p39 capsid and polyhedrin genes were initially transcribed at approximately 20 and 24 h p.i., respectively. Viral DNA replication...

Gypsy moths originating in Asia have recently been introduced into North America, making it necessary to develop markers for distinguishing the Asian strain from the established North American population. We have identified 3 randomly amplified polymorphic DNA-polymerase chain reaction generated (RAPD-PCR) markers which are specific for either Asian or North American moths. The FS-2 and FS-3 markers are specific for the North American strain, and the FS-4 marker is specific for moths from far east Asia. The 3 RAPD-amplified fragments have been cloned and sequenced, and locus-specific...

We previously demonstrated that polyhedron formation (PF) mutants arise at a high frequency during serial passage of the Lymantria dispar nucleopolyhedrovirus (LdMNPV) in the L. dispar 652Y cell line (J.M. Slavicek, N. Hayes-Plazolles, and M.E. Kelly, Biol. Control 5:251-261, 1995). Most of these PF mutants exhibited the traits of few polyhedra (FP) mutants; however, no large DNA insertions or deletions that correlated with the appearance of the FP phenotype were found. In this study, we have characterized several of the PF mutants at the phenotypic and genetic levels. Genetic techniques...

A Lymantria dispar nuclear polyhedrosis virus (LdMNPV) gene has been identified that encodes a homolog to the granulovirus (GV) enhancin proteins that are capable of enhancing the infection of other baculoviruses. Enhancin genes have been identified and sequenced for three species of GVs but have not been found in any other nuclear polyhedrosis virus to date. The LdMNPV enhancin gene is located between 67.6 and 70.1 kbp on the viral genome. Northern and primer extension analyses of viral RNAs indicate that the enhancin gene transcripts are expressed at late times postinfection from a...

Sugar maple (Acer saccharum Marsh.) has been declining across the unglaciated Allegheny Plateau in northwestern and north central Pennsylvania since the mid-1980s. A long-term study to evaluate the effects of fencing, herbicide, and liming on growth, crown vigor, and regeneration of sugar maple and associated Allegheny hardwoods was initiated in 1985. The study is a split-plot design with fencing (fence - no fence) as the whole-plot treatment and four subplot treatments: applications of herbicide (glyphosate) to control interfering vegetation, dolomitic lime (22.4 Mg.ha-1) to reduce soil...

In 1996 we investigated dispersal and survival of juvenile Tawny Owls (Strix aluco) by radio-tracking in Kielder Forest, Northumberland, a man-made conifer forest in northern England. Here, Tawny Owls fed largely on field voles (Microtus agrestis) which exhibited a 3-4 year cycle of abundance, with some spatial asynchrony. Generally, vole numbers were at the low point of the cycle in 1996. Twenty-two nestlings from 11 two-chick broods were radio-tagged when 22-31 (mean 26.3) days old. Birds fledged when 29-36 (mean 32.1) days old. Eight (36.4 percent) owls died 10-106 days after fledging...

We investigated Great Gray Owl (Strix nebulosa) habitat use in eastern Idaho and northwestern Wyoming. Great Gray Owls were not found in severely altered habitats, but young were fledged in areas where 17 to 26 percent of formerly continuous forest had been clearcut. Average clutch (2.7) and brood (2.3) sizes were comparable to other populations, whereas juvenile mortality in the first 60 days post-fledging may have exceeded 60 percent. Habitat features were measured at independent owl activity locations, and compared pairwise with measurements at associated random points. Fledged juveniles...