نتایج جستجو برای: short time exclosure
تعداد نتایج: 2216279 فیلتر نتایج به سال:
Exotic plant invasions and chronic high levels of herbivory are two of the major biotic stressors impacting temperate forest ecosystems in eastern North America, and the two problems are often linked. We used a 4-ha deer exclosure maintained since 1991 to examine the influence of a generalist herbivore, white-tailed deer (Odocoileus virginianus), on the abundance of four exotic invasive (Rosa m...
The effect of cattle grazing on the genetic structure of native grass populations has received little attention. We investigated the effect of cattle grazing on genetic variation in Idaho fescue (Festuca idahoensis Elmer) using ISSR (inter-simple sequence repeat) DNA markers. The ISSR markers are hypervariable and are generally interpreted as being selectively neutral. Idaho fescue tillers were...
this study aimed to investigate the effect of animal grazing on soil seed bank characteristics in the northern slopes of alborz. for this purpose, soil seed bank characteristics were compared between grazed and ungrazed areas. therefore, four transects perpendicular to the sides of exclosure inside and outside of it were established. then soil samples were collected within 28 plots inside and 2...
Abstract Over the last fifty years, most of the semi-arid rangeland in Iran has been converted to cropland without an equivalent reduction in grazing animals. This shift has led to heavy grazing pressure on rangeland vegetation. The present study has been conducted in Sisab Research Station in the North Khorasan Province to evaluate effects of long-term grazing exclosures on biodiversity of ra...
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...
the purpose of this study was to examine the comparative effect of story retelling and role playing on efl learners’ vocabulary learning and reading comprehension. to carry out the purpose of the study 90 female learners of tabarestan language school located in noshahr were non-randomly selected. they took pet test and among these 90 participants 62 students were selected as homogenous learners...
Overgrazing, via harvesting of forage species and decrease the other herbs, is of progressive factors in biodiversity destroying. In order to investigate the animal grazing impacts on changing of plant structure and diversity, we selected the comparison between this effect with exclosure area, and proving of the excluded area effects on plant diversity; two sites of Kojour rangeland, Mazandran ...
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