نتایج جستجو برای: mature trees
تعداد نتایج: 156488 فیلتر نتایج به سال:
The present study introduces a method to identify tree stems from terrestrial laser scanning (TLS) data. We focused on forest environments of diverse and layered structure, which were technically characterized by strong occlusion effects with regards to laser scanning. The number and distribution of tree stems are important information for the management of protective forests against natural ha...
Ostrya virginiana (Mill.) K. Koch is a useful and durable native tree that is infrequently planted. The literature contains little reliable information about the species. General characteristics of Ostrya are discussed and available information is presented on growth rate, pest problems, soil and moisture requirements, root system characteristics, propagation and nursery practices, and transpla...
Nitrate reductase utilizing NADH or reduced flavin mononucleotide (FMNH(2)) as electron donor was extracted from the leaves, stems and petioles, and roots of apple seedlings. Successful extraction was made possible by the use of insoluble polyvinylpyrrolidone (Polyclar AT) which forms insoluble complexes with polyphenols and tannins. The level of nitrate reductase per gram fresh weight was high...
and elevated ozone on tissue water relations of mature clones of a fast-growing genotype of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) and their half-sib seedlings. Whole seedlings and branches of mature trees were exposed to acid rain (pH 5.1 and 3.0) and ozone (ambient and twice-ambient) treatments in open-bottomed chambers. The acid rain treatment was applied to foliage weekly from Jan...
Forest management alters species behaviours, distributions and interactions. To evaluate forestry effects on ant foraging performance, we compared the quality and quantity of honeydew harvested by ants among clear-cuts, middle-aged and mature spruce-dominated stands in boreal forests in Sweden. Honeydew quality was examined using honeydew collected by squeezing the gasters of laden Formica aqui...
* A lack of data on responses of mature tree growth and water use to ambient ozone (O(3)) concentrations has been a major limitation in efforts to understand and model responses of forests to current and future changes in climate. * Here, hourly to seasonal patterns of stem growth and sap flow velocity were examined in mature trees from a mixed deciduous forest in eastern Tennessee (USA) to eva...
In April 1996, a phytoremediation field demonstration site at the Naval Air Station, Fort Worth, Texas, was developed to remediate shallow oxic ground water (< 3.7 m deep) contaminated with chlorinated ethenes. Microbial populations were sampled in February and June 1998. The populations under the newly planted cottonwood trees had not yet matured to an anaerobic community that could dechlorina...
Cecropia glaziovi Sneth. (syn. C. glaziovii, C. glazioui) (Cecropiaceae) is a South American medicinal plant whose antihypertensive activity is attributed to its flavonoid and proanthocyanidin contents. The seasonal and intraspecific variations of these two classes of compounds in C. glaziovi leaves were assayed by spectrophotometry in samples of young and mature leaves collected from native, c...
Large old trees are disproportionate providers of structural elements (e.g. hollows, coarse woody debris), which are crucial habitat resources for many species. The decline of large old trees in modified landscapes is of global conservation concern. Once large old trees are removed, they are difficult to replace in the short term due to typically prolonged time periods needed for trees to matur...
BACKGROUND Coppicing was one of the most important forest management systems in Europe documented in prehistory as well as in the Middle Ages. However, coppicing was gradually abandoned by the mid-20(th) century, which has altered the ecosystem structure, diversity and function of coppice woods. METHODOLOGY/PRINCIPAL FINDINGS Our aim was to disentangle factors shaping the historical growth dy...
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