نتایج جستجو برای: pine trees
تعداد نتایج: 104582 فیلتر نتایج به سال:
Southern pine beetles and associated pathogenic fungi represent the largest biotic threat to pine forests in the southeastern USA. The two primary defensive mechanisms of the tree to the beetle-fungal complex are the primary oleoresin flow and the concentrations of preformed and induced secondary compounds. We compared oleoresin flow and concentrations of phloem nutrients, soluble sugars, starc...
Steady state gene frequencies around a suming single gene inheritance and no dompocket of differential fitness have been forinance, Teich (1970) demonstrated that mulated by Hanson (1966) in a generalizapopulations of both jack pine and lodgepole tion of the work of Haldane (1948). A pine (Pinus contorta Dougl.) fit Hardypocket of differential fitness would result Weinberg expectations. The ele...
-We evaluated selection of nest sites by male Red-cockaded Woodpeckers (Picoides borealis) in Texas relative to the age of the cavity when only cavities excavated by the woodpeckers were available and when both naturally excavated cavities and artificial cavities were available. We also evaluated nest-cavity selection relative to the ability of naturally excavated cavity trees to produce resin,...
The dataset supplied in this article provides the spatial location and the species composition of urban trees belonging to three coniferous genera (Pinus, Cedrus and Pseudotsuga) inventoried in 5 districts of the city of Orléans (France). A total of 9321 trees were georeferenced. The most abundant species was the black pine Pinus nigra for which a total of 2420 trees were observed. Other common...
The paper analyses biometrical and anatomical traits of wood in a leaning stem of pine trees. For study purpose, five pine trees (Pinus sylvestris L.) with a visibly leaning stem were chosen. Wood samples were taken at three different stem heights, that is, below the stem curvature, at the curvature and above the curvature. Microscopic specimens were prepared and used for the following measurem...
—We documented black bears (Ursus americanus) consuming the seeds of Jeffery pine (Pinus jeffreyi) in the eastern Sierra Nevada from late August through September. Shells of pine seeds were the exclusive item in 20 of 27 scat samples collected in September and October and comprised >90% of the remaining 7 samples. Bears obtain seeds of Jeffrey pines by climbing trees, removing ripe, unopened co...
Oleoresin flow is an important factor in the resistance of pines to attack by southern pine beetle, Dendroctonus frontalis Zimm., and its associated fungi. Abiotic factors, such as nutrient supply and water relations, have the potential to modify this plant-insect-fungus interaction; however, little is known of the effects of inoculation with beetle-associated fungi on oleoresin flow. We observ...
Fuel-reduction/forest restoration treatments that consist of thinning followed by prescribed burning are becoming increasingly important land management actions that likely affect various wildlife species. To assess potential effects on bark-gleaning birds, we compared the foraging patterns of five cavity-nesting species in thinned and burned ponderosa pine (Pinus ponderosa) forest sites and co...
During the past 3 yr, nematologists in the United States have found specimens of Bursaphelenchus sp. in the wood of dead and dying pine trees. This nematode-host association resembles a similar interaction reported from Japan where pine trees are being killed by the pine wood nematode. This taxonomic research was conducted to determine if the Japanese pine wood nematode and similar populations ...
Conifers exhibit a number of constitutive and induced mechanisms to defend against attack by pests and pathogens such as mountain pine beetle (Dendroctonus ponderosae Hopkins) and their fungal associates. Ecological studies have demonstrated that stressed trees are more susceptible to attack by mountain pine beetle than their healthy counterparts. In this study, we tested the hypothesis that wa...
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