Document Type : Research Paper
Authors
1 M.Sc Student, Department of Range and Watershed Management, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Iran
2 Assistant Professor, Department of Range and Watershed Management, Faculty of Natural Resources and Environment, Ferdowsi University of Mashhad, Mashhad, Iran
Abstract
Rangeland shrubs may provide mechanical facilitation on their understory plants, by protecting them
against the livestock grazing. However, such a facilitation effect may vary depending on the rangeland
utilization rate. In a field research, mechanical facilitation of rangeland shrubs was compared in a
highly grazed, a moderately grazed and an enclosure site; in an arid rangeland, Kakhak, Gonabad,
Iran, during spring to summer 2011. Twenty line transects were established in various directions and
slope aspects. Forage production was measured by clipping method within the paired plots, i.e. under
the canopy of nursing shrubs and their nearby open areas. In the enclosure site, forage production was
similar under the canopy of shrubs and in open areas, whereas in the highly and moderately grazed
sites there were more forage under the canopies. These results indicate increases in mechanical
facilitation of rangeland shrubs by increasing the grazing intensity. The mechanical facilitation was
also varied depending on the life forms of understory species. In the enclosure, the greatest facilitation
was on annual forbs, whereas in the highly grazed site it was on perennial grasses. Results of this
study show important role of rangeland shrubs on preserving understory forage plant against the
intense livestock grazing.
Keywords
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