Interannual variation in the climate and above-ground biomass of Leymus chinense steppe and Stipa grandis steppe in the Xilin river basin, Inner Mongolia, China

We evaluated the relationship between variability in climate and variability in primary production and efficiencies of water use of Leymus chinense steppe and Stipa grandis steppe during 1980–89. On average, annual precipitation was 313•3 mm, while peak above-ground live biomass (PALB) and peak standing crop (PSC) were 182•68 g.m−2 and 193•48 g.m−2 for L. chinense steppe, 144•43 g.m−2 and 152•12 g.m−2 for S. grandis steppe. The coefficient of variation (CV) in annual precipitation was 22%, while the CV in PALB and PSC were 29% and 26% for L. chinense steppe, 24% and 25% for S. grandis steppe. Rain-use efficiency was 6•3 kgDM.ha−1mm−1year−1 for L. chinense steppe and 4•9 for S. grandis steppe, using PSC as the estimate of ANPP. Monthly and seasonal patterns of precipitation were as important as annual precipitation in determining responses of these two steppes