نتایج جستجو برای: short time exclosure
تعداد نتایج: 2216279 فیلتر نتایج به سال:
Exclosure experiments have demonstrated the effects of bird predation on arthropods. In a Mexican coffee plantation, we excluded foliage-gleaning bird and bat predators from coffee plants. Effects of bats and birds were additive. In the dry season, birds reduced arthropods in coffee plants by 30%; birds and bats together reduced arthropods by 46%. In the wet season, bats reduced arthropods by 8...
conservation and restoration of biodiversity is very important for degraded rangeland ecosystems. it is necessary to assess the potential of soil seed bank as a major source of species. in this study, the soil seed bank size and composition were compared between exclosure and grazed areas. this was done in chahar-bagh rangelands in golestan province. soil was sampled in exclosure and grazing fr...
background: pentoxifylline (px) prevents camp breakdown by inhibiting the activity of the camp-phosphatase and presumably, stimulates sperm motion. incubation with px causes hyperactivation of sperm, an important step in achieving fertilization, and leads to changes in membranes associated with sperm capacitation. objective: the purpose of this study was to examine the effects of pentoxifylline...
The study of vegetation dynamics under grazed and non-grazed rangelands is one of the most important prerequisites for range improvement. In this research, vegetation composition and the vegetation functional groups were compared in an exclosure site (livestock excluded for six years) and grazed area in semi-steppe rangelands in Tehran province. Systematic random sampling technique through the...
the effect of exclosure on the changes of vegetation cover of rangelands of ahmad-abad region located in zanjan province has been studied during 2002 to 2006. three transects comprises of 60 fixed quadrate were establish within exclosure area and outside as well. the changes of vegetation cover were studied to made comparison between the changes of manipulated factors and soil elements using t ...
1. Herbivores influence the structure and composition of terrestrial plant communities. However, responses of plant communities to herbivory are variable and depend on environmental conditions, herbivore identity and herbivore abundance. As anthropogenic impacts continue to drive large declines in wild herbivores, understanding the context dependence of herbivore impacts on plant communities be...
The study of the exclosure effects on the vegetation changes undergrazing and non-grazing conditions in the rangeland areas has particularimportance in the rangeland improvement and revivification projects. Theresearch was accomplished in semi-steppe KhoyBilehvar area, from 1999 to2005. Vegetation cover was annually measured within fixed plots during transact.The results showed that during nine...
It has been suggested that tropical defaunation may unleash community-wide cascading effects, leading to reductions in plant diversity. However, experimental evidence establishing cause-effect relationships thereof is poor. Through a 5 year exclosure experiment, we tested the hypothesis that mammalian defaunation affects tree seedling/sapling community dynamics leading to reductions in understo...
Catherine A. Gehring,* Julie E. Wolf and Tad C. Theimer Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 860115640, USA Research School of Biological Sciences, Australian National University, Canberra, ACT 0200, Australia *Correspondence: E-mail: catherine.gehring@ nau.edu Abstract We examined whether terrestrial vertebrates affected the arbuscular mycorrhizal funga...
Different species-specific traits of woody plant species, feeding preferences herbivores together with resulting effects on competition are expected to translate into different community structures and expressions biodiversity. We studied the diversity species (trees shrubs) structural forest trees, using a 30-year an 18-year dataset ungulate exclosure-control plot pairs in mixed alpine Austria...
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