Effect of Different Grazing Intensities on Diversity and Plants Cover Composition in Semi-Arid Grazing(Case study: Mohammad Abad, Jiroft)

It is necessary to be aware of the destructive factors in the ecosystem. These factors cause shelter and biomass destruction, thus decreasing species diversity. Livestock over grazing is one of the most physical destructive pressures on rangeland that leads to a decrease in diversity and vegetation elements. The aim of this study has been conducted to investigate the effect of different grazing intensities on the diversity and richness of plant species in the semi-arid rangelands of Mohammad Abad area of Jiroft, Kerman Province, Iran.

We selected 3 sites that included light, moderate and heavy grazing intensities. Sampling was performed using 90 plots (2 m2) along 18 transects. The list of specie, canopy coverage and number of individuals per species were recorded for each sampling unit. To evaluate diversity and richness of the plant species, Margalef and Menhing richness indices, and Simpson, Shannon, Hill N0 and Hill N1 diversity indices were calculated. SPSS software was applied for data analysis. Comparison of different indices of diversity and richness among study sites was performed by the Tukey test.

The results of Margalef richness index showed significant differences between all grazing sites. No significant difference existed in the Menhing richness index of different grazing categories (p<0.01). Results of calculations of diversity indices for Simpson, Shannon, Hill N0 and Hill N1 showed that there were significant difference (p<0.01) between all grazing sites.

Generally, diversity and species richness indices due to low rainfall and placement in the semi-arid region are relatively low in the case study. Therefore, because of the sensitive and fragile nature of these types of rangelands in the operation, we should pay more attention to prevent further destruction and amended the composition.