نتایج جستجو برای: oak leaves
تعداد نتایج: 88097 فیلتر نتایج به سال:
1. Environmental heterogeneity created by prescribed burning provided the context for testing whether the distribution of an oak specialist (the lace bug, Corythuca arcuata ) could be explained by stoichiometric mismatches between herbivore and host plant composition. 2. Field observations showed that lace bug density was seven-fold higher in frequently burned than in unburned units. 3. Lace bu...
1. Secondary colonization of leaf shelters constructed by caterpillars has been reported from a number of systems. Both the mechanism (larval or adult movement vs. oviposition) and the cues used by arthropods in locating leaf shelters, however, have received little attention. 2. Artificial leaf shelters (i.e. leaf ties or pairs of leaves clipped together to form sandwiches) were constructed on ...
Earlier studies have shown that the activity of the estuarine detrital microflora measured by various enzyme activities, muramic acid and adenosine 5'-triphosphate (ATP) content, heterotrophic potentials, and respiratory activities correlates with the incorporation of C and P into the microbial lipids. In this study, these lipids were reproducibly fractionated into neutral lipid, glycolipid, an...
Oak decline is a chronic problem in Missouri Ozark forests. Red oak group species are most susceptible and decline is reportedly more severe on droughty, nutrient-poor sites. However, it was not clear whether greater decline severity was caused by poor site conditions or is simply due to the greater abundance of red oak group species found on poorer sites. We conducted this study to determine w...
Shortleaf pine-oak-hickory woodlands provided the principal vegetation cover in the Tallahassee Red Hills prior to land clearing for plantation agriculture in the 19th century. Ample historical documentation and extant remnants of that community, including old-growth, support this conclusion. This woodland was maintained by surface fires and consisted principally of open stands of shortleaf pin...
Oak decline, the precipitous mortality of mature oak trees, has been a chronic problem in xeric oak ecosystems and is reaching unprecedented levels in red oak group (Quercus section Lobatae) species in the Ozark Highlands. The high rates of mortality are leading to rapid changes in species composition, forest structure, and related changes in fire risk, insect populations, and colonization patt...
The traditional approach to spreadsheet auditing generally consists of auditing every distinct formula within a spreadsheet. Although tools are developed to support auditors during this process, the approach is still very time consuming and therefore relatively expensive. As an alternative to the traditional 'control through' approach, this paper discusses a 'control around' approach. Within th...
Oak decline is a process induced by complex interactions of predisposing factors, inciting factors, and contributing factors operating at tree, stand, and landscape scales. It has greatly altered species composition and stand structure in affected areas. Thinning, clearcutting, and group selection are widely adopted harvest alternatives for reducing forest vulnerability to oak decline by removi...
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