Hamidreza Akafi; Hamid Ejtehadi; Adel Sepehri
Volume 24, Issue 4 , January 2018, , Pages 907-919
Abstract
Recognition of spatial distribution pattern of plants is useful in describing the ecosystem stability, designing management plans and protective rehabilitative measures. In order to determine the distribution pattern of certain plant species in Ghamishloo National Park, six safe regions were selected. ...
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Recognition of spatial distribution pattern of plants is useful in describing the ecosystem stability, designing management plans and protective rehabilitative measures. In order to determine the distribution pattern of certain plant species in Ghamishloo National Park, six safe regions were selected. Three hundred sixty quadrates with the size of 1×1 m2 were established by using random-systematic method along six transects and the number of individuals of each species was recorded. In this study, dispersion indices such as clustering, Green, Lloyd and Morisita were used. Since a large number of plants with different densities were selected, the results of indices showed that density had no effect on distribution pattern. The values of Green's index showed a pattern between random and non-random (clumped) distribution pattern. Therefore, it is recommended to use maximum clumped values to determine the exact type of distribution pattern. Among the study indices, no specified maximum value was defined for Lioyd and Morisita regarding the clumped pattern. For this purpose, two formulas were defined to determine the maximum clumping and the results of indices were interpreted according to these formula.
Fahimeh Rafiee; Mohammad Jangjou; Hamid Ejehadi
Volume 22, Issue 1 , June 2015, , Pages 73-85
Abstract
Plant traits can be used to study the mechanism of vegetation responses to the environmental disturbances. This study was aimed to study the changes in plant traits, in six-and two- year periods after wildfires in a semiarid rangeland. Three adjacent sites (control, burnt at 2004, burnt at 2008) were ...
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Plant traits can be used to study the mechanism of vegetation responses to the environmental disturbances. This study was aimed to study the changes in plant traits, in six-and two- year periods after wildfires in a semiarid rangeland. Three adjacent sites (control, burnt at 2004, burnt at 2008) were selected in Jowzak rangelands, Northern Khorasan, Iran. Plant sampling was conducted at spring and summer 2010. Floristic list was recorded in each site; also, 58 morphological, phonological and reproductive plant traits were measured. Results indicated four different responses by plant traits to the chronological wildfires. Type1 no response; 37 traits were not affected by the wildfires. Type2 adapted traits: annual plants were increased by times after burning. Type3 tolerant traits: plant with spins, hairs, prostrate canopy, rosette and elongated leaves, ramified stems, scattering by seeds, reproduction by seeds and/or rhizomes, and leaf phenology more than three months initially increased but finally reduced. Type 4 sensitive traits; perennial grasses, shrubs, scopus canopy, non-spiny, succulent leaves and stem elongated leaves gradually decreased with times after burning. In conclusion, plant traits have important roles in determining the responses of plant species to the environmental disturbances; hence, they can affect the secondary succession after the wildfire in rangelands.
Maryam Nikan; Hamid Ejtehadi; Mohammad Jangju; Farshid Memariani; Hajar Hasanpour; Fariba Noadoost
Volume 19, Issue 2 , September 2012, , Pages 306-320
Abstract
Livestock grazing is one of the most influencing factors on the rangeland community structure and composition, which can also change the vegetation diversity. The main aim of this research was to survey the flora and plant biodiversity at three rangeland sites, being used under different grazing intensities, ...
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Livestock grazing is one of the most influencing factors on the rangeland community structure and composition, which can also change the vegetation diversity. The main aim of this research was to survey the flora and plant biodiversity at three rangeland sites, being used under different grazing intensities, Baharkish, Quchan, Iran. Three sites were systematically selected along a spatial gradient of low, moderate and high grazing intensity, and 20 quadrates were randomly established within each site. Species composition, abundance and canopy cover were recorded within the quadrates. Simpson and Shannon diversity and Carmago and Smith & Wilson evenness indices were measured for each site. Floristic studies led to the identification of 156 plant species belonging to 34 families. The floristic composition of the area was strongly dominated by the Irano-Touranian elements. Shannon and Simpson diversity indices were significantly higher under the moderate than the low and heavy grazing intensity sites and the lowest diversity was significantly recorded for the heavy grazing site. Evenness indices did not significantly differ between the low and moderate grazing sites, but it was significantly lower under the high grazing site. In conclusion, proper livestock grazing is necessary for preservation of species diversity in the semiarid rangelands; Moderate grazing maintained the species diversity while light and sever grazing reduced or even eliminated some sensitive plant species.