Determination of effective environmental factors on plants functional diversity and species diversity in Ravar rangelands

The aim of the study was to investigate affecting environmental factors on functional diversity indices and species diversity for the fluctuation of the management according to the ecological conditions in Raver rangeland. To determine the functional attributes of rangeland plants, 12 height points were selected along elevation gradient those were distance between them100 meters. 5 sampling plots were established at any point along transects perpendicular to the slope. 60 plots were harvested totally. 3 soil samples were taken from 10 to 20 cm depth in each point. Then soil properties including relative moisture, percent of silt, clay and sand, OM, N, P, K, EC, CaCo3 and pH were measured in laboratory. 6 functional traits including plant height, growth form, type of reproduction, longevity, life form and type of nitrogen-fixing measure. 8 functional diversity indices including Rao (Rao), multiple convex (Rao), Functional richness (FRic), Functional Eveness (FEve), Function Divergence (FDiv), the distribution function (FDis), a variety of features function (FAD1) index modified variety of performance characteristics (FAD2) and four species diversity indices were calculated with software FDivrsity. To investigate the relationship between environmental factors, plant species and functional and species diversity indices were used multivariate analysis (DCA, CCA, and RDA). The results showed that factors such as altitude, the percentage of lime, organic matter and moisture have the greatest impact on plant. The results of the correlation between environmental variables with functional variation showed that the highest correlation for the first axis is related to the initial moisture content of 0.44 and the second axis with respect to silt with a value of 3817.0. Also, the correlation between environmental factors indicated that high correlation between moisture (r = 0.61), EC (r = 0.75), pH (r = 0.68), organic matter (r = 0.78), silt (r = 0.72) and elevation of sea level (r = 0.77) with the first axis of the species. The correlation between functional diversity varieties and species richness indicates that most of the indicators have increased with increasing species richness. Only the CHull index has been reduced with increasing species richness, and the uniformity of performance and richness of species richness have not been significantly correlated plant species.