干旱区生态环境知识资源中心

Net primary productivity of a grazingland dominated by perennial grass Sporobolus marginatus Hochst. ex A. Rich at Bhavnagar, a coastal and semi-arid zone in the Saurashtra region of the Gujarat State was studied. The seasonal variation in the above-ground biomass (AGB) of the community corresponded with the seasonal distribution of rainfall. Only S. marginatus survived the hot summer months while the rest of its associates perished. Total net primary production of the grazingland for the year 1982-83 was 1,286.85 g m-2 (at a rate of 3.53 g m-2d-1). Above-ground biomass and below-ground biomass (BGB) attained the peak values in the month of August (441 02 gm-2) and January (329.84 gm-2), respectively. A postmonsoonal increase in BGB was noted. The annual above-ground and below-ground net production (ANP and BNP) were 787.77 gm-2 and 499,08 g m-2, respectively. The BNP contributed a little more than 61 per cent of the total net production.