Moslem Rostampour; Alireza Eftekhari
Abstract
This research was carried out in an enclosure rangeland with four habitats of Artemisia sieberi, Zygophyllum eurypterum, Stipa barba and Amygdalus scoparia in the Shaskouh protected area, South Khorasan province. All the plant species of the rangeland were identified and counted in 200 plots, due to ...
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This research was carried out in an enclosure rangeland with four habitats of Artemisia sieberi, Zygophyllum eurypterum, Stipa barba and Amygdalus scoparia in the Shaskouh protected area, South Khorasan province. All the plant species of the rangeland were identified and counted in 200 plots, due to the different vegetation form and distribution of each of the dominant species, in each of the four habitats, 20, 40, 60 and 80 plots (respectively) were established with two plot size: 2 × 2 meters and 4 × 4 meters (60 plots each). Numerical indices and diversity ordering curves were used to compare four habitats. Alpha and gamma species richness were determined by numerical indices and single sample rarefaction and pooled rarefaction curves were used to compare species richness and determine data adequacy. The results showed that the total species richness (gamma) varies between 51 and 54 species. The habitat with 80 plots has the highest richness and diversity (S=43 and H=3.27) and 20 plots has the lowest richness and diversity (S=6 and H=1.41). The results of SHE analysis showed that with the increase in the number of plots, species evenness decreased. The pooled refraction curve showed that by increasing the number of plot to 110, all plant species will be observed. With the increase in plot size all values of species richness and diversity indices increased significantly (p≤0.01). Species evenness indices were not affected by plot size. The results of the present research showed that the numerical indices of species richness and diversity are dependent on plot size, and this is one of the disadvantages of evaluating biodiversity in rangeland using numerical indices.
parisa niknam; Reza Erfanzadeh
Abstract
In this study, the effect of cushion plants on spatial distribution of soil seed bank was studied in mountainous and hilly rangelands in Vaz watershed, Mazandaran province. Therefore, we selected randomly 20 Onobrychis cornuta individuals and sampled from soil at four positions around each individual ...
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In this study, the effect of cushion plants on spatial distribution of soil seed bank was studied in mountainous and hilly rangelands in Vaz watershed, Mazandaran province. Therefore, we selected randomly 20 Onobrychis cornuta individuals and sampled from soil at four positions around each individual (upslope, downslope, center and, outside as control). Soil samples spread out under natural conditions in greenhouse to germinate the seeds. Germinated seeds were identified then, the seed density per square meter and species richness were calculated and both of them were compared between the four sampling positions. Two and one-way ANOVA, T-test and Duncan test were used to compare the effect of location, depth and their interaction on soil seed bank characteristics. The results showed that the effect of the location and depth of the density and species richness at level of 0.01% were significant. The results of Duncan test showed that seed density in the upslope and center positions (average 5473 and 4099.5 seed/m2, respectively) was significantly higher than seed density in the downslope and outside positions (average 2685.5 and 2413.8 seed/m2, respectively). Similarly, species richness in the upslope and center positions (the average 9.7 and 9.5, respectively) was significantly higher than species richness in the downslope and outside positions (average 7 and 6.4, respectively). Density and species richness of soil seed bank at depth of 0-5cm was significantly greater than the depth of 5-10cm. This study clarified the positive significant effect of canopy of cushion plants on seed density and richness.
