The effects of aboveground biomass variations on root system in in Leymus chinensis Steppe with different degradation degrees

FASTCLUS method was used to classify Leymus chinensis steppe in Dalinuoer natural reserve,Keshiketeng Banner of Chifeng City,Inner Mongolia.The grasslands were classified quantitatively into areas with different degrees of degradation according to plant community characteristics,which indicated there were three different degradation degrees with the distance of 0-1 700 m,1 700-2 700 m and 2 700-4 100 m respectively.We explored the effects of aboveground biomass variations on root system among different communities.The results showed that underground biomass variations had no relevant decreasing tendencies with more human disturbances and less biomass aboveground.The area under moderate grazing pressures(0-1 700 m) had the maximum underground biomass.The differences of underground biomass among communities with different degradation degrees were mainly caused by root biomass accumulated in the layer of 0-10 cm top soil.