DYNAMICS OF ABOVE GROUND HERBACEOUS BIOMASS IN HIGH ALTITUDE RANGELANDS OF PAKISTAN

Periodic monitoring of above ground biomass is a vital component for effective management of rangelands health and productivity. Rangelands in Gilgit-Baltistan are dominant land-use forms, spanning over 25% (16450.5 km(2)) of its total area, and contributing about 30-40% in the total household income. The present research is an attempt to document the field based above ground biomass assessment of selected rangelands in the Hindu-Kush, Karakorum and Himalayan (HKH) regions of Pakistan and to relate it with the current livestock numbers in order to assess the grazing pressure on these rangelands. Five sampling plots (1km(2)) at 17 catchments of five watersheds, representing the three mountain ranges were randomly selected for the study. The mean elevation of sampling plots ranged from 2500 m to 4100 masl. Within each sampling plot 3 quadrats (1m(2)) were chosen, located, at least, 250 m apart from each other. For each of the sampling plot plant species were identified, biomass was calculated, and evenness and diversity of species was determined. On average the wet as well as dry biomass, across all the grazing areas was 2279 kg/ha and 650 kg/ha, respectively, with highest in Khunjerab (2831 and 704 kg/ha) and lowest in Bathraite (1590 and 596 kg/ha). About 138 species belonging to 27 families were recorded from the study areas. The highest species richness was found in the Deosai Plains (11) followed by Bathraite (10). It was observed that the grazing areas nearest to the permanent settlement have highest non-palatable species, possibly due to extensive grazing. Grazing pressure in all pastures is increasing with maximum in Babosar and Bathraite, showing decline in productivity of the rangelands at these sites. Grazing management can improve pastures conditions as evident from high biomass in Khunjerab, attributed to grazing management under the National Park regime. This research will provide a baseline study for further research on rangeland management activities in the area and their sustainability.