关键词: 黄土高原, 达乌里胡枝子, 分布密度, 气候梯度, 乔木层, 灌木层, 草本层, 凋落物层, 叶片, 地理因子 

Abstract: Field survey and position monitoring were conducted from 2000 to 2009 to study the effects of climate change on the distribution and growth of Lespedeza davurica community on Loess Plateau. As affected by air temperature, the appropriate growth region of L. davurica community on the Plateau had an obvious zonal distribution from northwest to southeast. For the distribution of L. davurica community, the suitable air temperature was 7.4 ℃-10 ℃, average population density was 13.9 plants·m^-2, and reproductive branch was averagely 11.4 per cluster. As affected by precipitation gradient, the horizontal distribution of L. davurica community changed from a constructive or predominant species in typical grassland region into a companion species in forest steppe region, and then, the community gradually became dominant species. The L. davurica community appeared as an occasional species on the half sunny slope of gullies and valleys and the sand dunes in desert steppe region, and extended gradually from its optimal region with yearly precipitation 300-500 mm to the region with yearly precipitation 270-600 mm. Also, the L. davurica community extended from its
 optimal altitude 1100-1700 m to 600-1950 m. Under the background of global climate change, the eco-breadth of L. davurica community expanded gradually.

Key words: Loess Plateau, Lespedeza davurica, distributed density, climate gradient, tree layer, shrub layer, herb layer, litter layer, leaf, geographical factor.