IMPACT OF GRAZING ON PLANT BIODIVERSITY OF DESERT AREA OF DISTRICT KHAIRPUR, SINDH, PAKISTAN

The effect of grazing on desert plant species from three distinct habitats i.e. Kot Diji sand dune, Ubhan Shah flat dune and Sorah inter-dunal area of District Khairpur was studied by using quadrat method. We analyzed each plant species for cover, total plant cover of grazed, un-grazed and mean % reduction in cover (cm) from pre-monsoon and post-monsoon seasons. The results revealed a considerable effect of grazing on plant species; however the impact of grazing varied from plant to plant and season to season, in the studied areas. There was highest grazing intensity of Indigofera species leading to endanger in this area. In all sites, maximum reduction in cover was observed in Indigofera oblongifolia and Indigofera argentea, with 62.8 and 57.2cm, respectively during pre-monsoon, and 61.5 and 52.8cm in post-monsoon. Aristida funiculata also possesses high grazing intensity with 40.3 and 54.2cm in pre and post-monsoon seasons respectively. The species Convolvulus protratus, Cassia italica, Dipterygium glaucum and Digera arvensis showed grazing intensities with 47.8, 57.4, 25.2, 42.7 in pre-monsoon season and 44.3, 35.9, 45.7,53.7 in post monsoon seasons, respectively. The low grazing intensity was observed in dominant plant communities Aerva javanica, Calligonum polygonoides, and Leptadenia pyrotechnica in a pre-monsoon season with 7.8, 17.4, 13.2cm, whereas, it was increased in post-monsoon with 11.5, 25.9, 32 in the reduction of cover (cm), respectively. These plant species were grazed by the animals at that time when ephemerals were not available in the desert during a drought period. It is suggested that partial protection and controlled grazing can be beneficial to get positive results and maintain the desert vegetation in the study area.