نتایج جستجو برای: stands
تعداد نتایج: 21645 فیلتر نتایج به سال:
The invasive insect pest Adelges tsugae (Hemlock Woolly Adelgid) threatens the ecologically unique Tsuga canadensis (Eastern Hemlock)-dominated forest type throughout its range. Relatively little is known about how the loss of this forest type will affect the relative abundance of amphibians. This study assessed the relative abundance of the juvenile phase of Notophthalmus viridescens viridesce...
Spatial variation in vegetation and coarse wood is a major source of forest heterogeneity, yet little is known about how this affects ecosystem processes. In 15-year-old postfire lodgepole pine (Pinus contorta var. latifolia Englem.) stands in Yellowstone National Park, Wyoming, we investigated how the decomposition rate varies with the position of coarse wood and other dominant structures with...
Tree species proportions of forest stands were estimated using data measured by Toposys laser scanner. Employed estimation method was multilayer perceptron neural network with error back-propagation training algorithm. Measurements were divided into 2*2 m squares and then those measurement which were higher than determined DTM were used to compute features. The purpose of extracted features wer...
Stem maintenance respiration rates were measured in five contrasting balsam fir (Abies balsamea (L.) Mill.) stands. At 15 degrees C, average respiration rates for individual stands ranged from 120 to 235 micro mol m(-3) s(-1) when expressed per unit of sapwood volume, from 0.80 to 1.80 micro mol m(-2) s(-1) when expressed per unit of stem surface area, and from 0.50 to 1.00 micro mol g(-1) s(-1...
Background: Range species have different sensitivities to livestock grazing and this effect sometimes becomes much more important with the help of climatic conditions. If the amount of pasture exploitation is appropriate, Preservation of high-quality pasture and edible species and plant composition, as well as the durability of production in the pasture ecosystem, are guaranteed. Therefore, th...
Forest structure consider the spatial arrangement of trees characteristics such as age, size, species, gender and so on is.This study aimed to investigate the structural diversity of three one-hectare stands in the gap making phase, were studied. For this purpose, three sample plots with a one hectare area were selected in Asalem beech stands which belonged to the structural features of the gap...
Longleaf pine once was present on 90 million acres of the southern landscape, ranging from coastal Virginia to east Texas and from central Florida to the mountains of Alabama. On nearly two-thirds of that area, longleaf pine grew in nearly pure (single-species) stands maintained by frequent, low-intensity surface fires of both natural and human origin. The remaining one-third of that area was s...
BACKGROUND : Tree stands have remained popular among hunters because of the increased vantage point for the hunter. Although stand styles vary, the typical stand is very minimalistic in design, comprising a seat and an area for the hunter to place his feet. Although there have been studies using state trauma registry data, to date, there has not been a study on the epidemiology of tree stand-re...
Low elevation ponderosa pine (Pinus ponderosa Dougl. ex. Laws.) forests of the northern Rocky Mountains historically experienced frequent, low intensity fires that maintained open, uneven-aged stands. A century of fire suppression has led to denser ponderosa pine forests with higher competition for resources, higher tree stress, and greater risk of insect attack and stand destroying fire. Activ...
this study was designed to investigate the structural characteristics of beech forests in the middle stage of ecological succession. in order to this purpose undisturbed beech stands in kheyroud forest had chosen and three one hectare sampling plot laid out. all of tree species measured with full callipering method and diameter and height of trees were recorded. natural regeneration within one ...
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