changes in patterns of animal and plant diversity along with precipitation gradient has been widely recognized. However, it is still unknown about how and to what extent the precipitation affects the geogphical distribution of soil microbes.Based on the data from 3700km-long smpling belt in North China grasland and bacteria 16SrRNA gene sequencing,the bacterial diversity, spatial patterns of bacterial community composition and its driving force were analyzed. The findings are as folows: 1) Actinomycetes, Acidobacteria, α-Protobacteria, δ-Protobacteria, Quasi Bacillus and Plactomyces are dominate groups in soil of north-China arid and semiarid grassland. 2) Aridity index (MAP/MAT) is the most significant environment factor that affects the diversity of bacterial community and community composition. The drier the area, the lower the bacterial diversity., but there is obvious spatial variations. 3) Aridity is also a factor influencing relative abundance of dominant bacterial groups. 4) The  patterns of species abundance of bacteria differs from plant, but similar to big animals in locality. 5) The similarity of bacterialcommunity decreases with increased geographical and environmental distance. The geographical diatance is another fctor affecting bacterial community composition.6) Geographical distance explains more spatial variations in bacterial community. Along with increase in scale concerned, the effect becomes more and more significant. Tis indicates that the bacterial community composition and diversity patterns on arid and semiarid frasslan are driven by both historical (such as dispersal limitation) and mordern environmental heterogeneity.

The results were published in FEMS Microbiology Ecology.

Xiaobo Wang, JoyD. VanNostrand, Ye Deng, Xiaotao Lü, Chao Wang, Jizhong Zhou, Xingguo Han*. 2015. Scale-dependent effects of climate and geographic distance on bacterial diversity patterns across northern China's grasslands. FEMS Microbiology Ecology, doi: 10.1093/femsec/fiv133 (IF: 3.568).