Treesearch

Studies of the California spotted owl have revealed significant selection for habitats with large, old trees; relatively high basal areas of snags; and relatively high biomass in large, downed logs. Based on planning documents for national forests in the Sierra Nevada, we projected declining amounts of older-forest attributes. Region 5 has adopted measures to retain these attributes, generally distributed throughout the conifer zone, for an interim period. We believe that a long-term strategy for the owls, and for other species associated with older forests, must retain some level of these...

The effect of repeated prescribed burning on long term growth of Pinus ponderosa in northern Arizona was examined. Fire treatments for hazard reduction were initiated in 1976,and growthwas evaluated in 1988 for fire rotations of 1, 2, 4, 6, 8, and 10 years. Dendroecological analysis shows that there were only small changes in treegrowth (compared tocontrols) in the first few years after the initial fire treatment despite large fuel reductions and thinning, and that annual precipitation was positively correlated with growth. Moderate changes in growth relative to that of control trees were...

The geographic range of the Douglas-fir twig beetle, Pityophthorus orarius Bright, was extended beyond the original provenance of southern British Columbia to northern California. A survey of 457 Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] trees in 1985 revealed that those with heavy cone crops were more likely to be infested by twig beetles than were those with a light crop. Furthermore, attack rates differed among clones. A second survey done in 1987 confirmed the importance of clone and cone crop in attack rate. In this survey, stressed trees were attacked at a higher rate than...

Watershed analysis-the evaluation of processes that affect ecosystems and resources in a watershed-is now being carried out by Federal land-management and regulatory agencies on Federal lands of the Pacific Northwest. Methods used differ from those of other implementations of watershed analysis because objectives and opportunities differ. In particular, Federal management must take into account the full range of uses and values present, so interagency watershed analysis includes wildlife, social, and economic components in addition to the physical and aquatic evaluations shared by other...

We report the identification of quantitative trait loci (QTL) influencing wood specific gravity (WSG) in an outbred pedigree of loblolly pine (Pinus taeda L.) . QTL mapping in an outcrossing species is complicated by the presence of multiple alleles (>2) at QTL and marker loci. Multiple alleles at QTL allow the examination of interaction among alleles at QTL (deviation from additive gene action). Restriction fragment length polymorphism (RFLP) marker genotypes and wood specific gravity phenotypes were determined for 177 progeny. Two RFLP linkage maps were constructed, representing maternal...