Abstract:Hulunber steppe with a plateau landscape is a component of the Mongolian Plateau of central Asia and located in the eastern part of Inner Mongolian. Its elevation is almost over 600 meters, and the ground-surface is undulated due to hilly distribution and precipitation decrease from the east to west following the climatic change from sub-humid to semi-arid. The region of ecological space expanded greatly as complex terrain small changes, and the relationship between vegetation and environment is complicated. Our study is focused on the effect of the terrain and the influence of soil-environment on the structure of Hulunber steppe communities.
A DCCA was used to quantitatively analyze the relationship between soil and topographic factors, both of which influenced the changes of community structure based on field experiment in 2006 in Hulunber grassland. The results showed that the pure soil environmental factors can explain 12.48% of the species diversity change, and the pure topographic factors can explain 8.34% of the species diversity change. 4.76% can be explained by the latter two factors and the unexplainable parts were 74.42%. Topographic factors played an important role to community structure by affecting the reallocation of the hydro-thermal combination. Among all the factors, total soil nitrogen, effective potassium and nitrogen, available phosphorus, organic matter and the slope shape decide the changes of the communities’ niche, which lead to changes of the communities’ types distribution gradient.