نتایج جستجو برای: term exclosure
تعداد نتایج: 581600 فیلتر نتایج به سال:
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...
We report long-term patterns of quaking aspen (Populus tremuloidesMichx.) recruitment for five ungulate exclosures in the northern ungulate winter range of Yellowstone National Park. Aspen recruitment was low (<3 aspen·ha−1·year−1) in the mid-1900s prior to exclosure constructiondue toherbivorybyRockyMountain elk (Cervus elaphus Linnaeus, 1758) but increasedmore than60-fold within 25 years afte...
to compare the seed characteristics in accessions of atriplex canescens under exclosure and non-exclosure conditions, two even-aged sites were selected with an area of 400 ha as the exclosure and 1000 ha as non-exclosure area. to conduct the study, 30 species were randomly selected in autumn 2009 in reference area of the sites and seeds were collected. some important seed characteristics were s...
Snowshoe hare populations in the boreal forests of North America go through 10-year cycles. Supplemental food and mammalian predator abundance were manipulated in a factorial design on 1-square-kilometer areas for 8 years in the Yukon. Two blocks of forest were fertilized to test for nutrient effects. Predator exclosure doubled and food addition tripled hare density during the cyclic peak and d...
Concentrated herbivory by elk (Cervus elaphus) can degrade vegetative communities and alter ecosystem processes. Areas severely damaged by elk are commonly protected with woven wire fence, which can exclude other animals. Complete exclusion and prevention of large mammal herbivory might not always be necessary to restore vegetative communities. We designed and evaluated a simple fence that excl...
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...
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...
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...
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...
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