Abstract: It is of significance to investigate soil moisture content and aboveground biomass under different terrains in desert steppe for understanding the effects of terrain on spatiotemporal heterogeneity of soil moisture content and aboveground biomass. Based on the TDR and field survey, we analyzed the heterogeneity of soil moisture content and aboveground biomass under 3 different terrains using the multivariate analyses, such as the oneway ANOVA, multiple comparison and Kriging interpolation. We also used the person correlation coefficient to analyze the relationship between soil moisture content and aboveground biomass and to clarify the effects of soil moisture content in different soil layers on vegetation at different growth stages.  The  results  are as follows: (1) The vertical distribution of soil moisture content was obvious, and CV was the lowest in soil layer of 0-20 cm but the highest in soil layer of  60-80 cm. The spatial heterogeneity of aboveground biomass was significant in whole growth season; (2) Soil moisture content and its spatiotemporal distribution pattern were different among the 3 different terrains, it means that terrain was the key factor affecting soil moisture content; (3) Terrain was not the main factor affecting the spatial variation of grassland productivity, and it affected significantly the dynamic vegetation growth but slightly the aboveground biomass; (4) The relationship between soil moisture content and aboveground biomass was different at different growth stages. Water consumption for vegetation growth at the initial growth stage was mainly from soil layer of 60-100 cm; there was a weak correlation between soil moisture content and biomass at other growth stages, which may be related to the formation time of drought-tolerant organs of plants.

Key words: desert steppe, terrain, soil moisture content, biomass, spatiotemporal, Yanchi country, Ningxia