TEMPORAL VARIATION IN ABOVEGROUND BIOMASS OF LEYMUS CHINENSE STEPPE FROM SPECIES TO COMMUNITY LEVELS IN THE XILIN RIVER BASIN, INNER-MONGOLIA, CHINA

We analyzed the long-term dynamics of aboveground biomass of Leymus ch inense steppe in relation to interannual variation of precipitation an d temperature during 1980-1989 at levels of community, growth form and species in the Xilin river basin, Inner Mongolia Autonomous Region, C hina. Annual aboveground net primary production (ANPP) varied from 154 .00 g m(-2) yr(-1) in 1980 to 318.59 g m(-2) yr(-1) in 1988, with a me an of 248.63 g m(-2) yr(-1) and the coefficient of variation of 25%. A NPP was not significantly correlated to annual precipitation and total precipitation during April-September at p less than or equal to 0.05 level, but precipitation in May and August accounted for 69% of intera nnual variation of ANPP. The means of rain use efficiency and water us e efficiency of L. chinense steppe were 8.1 kg DM ha(-1) mm(-1) yr(-1) and 0.89 mg DM g(-1) H2O respectively. Aboveground biomass of various growth forms and species had different response patterns to interannu al variation of precipitation and temperature. Monthly and seasonal di stribution of precipitation and temperature were the key controls of a boveground biomass of species.