R∶S Ratios of Temperate Steppe and the Environmental Controls in Inner Mongolia
MA Wenhong FANG Jingyun(Department of Ecology,College of Environmental Sciences,Center for Ecological Research & Education,and Key Laboratory for Earth Surface Processes of the Ministry of Education,Peking University,Beijing,100871)
Grasslands play a significant role in terrestrial ecosystem carbon cycle due to large biomass stored belowground. R∶S ratio (belowground to aboveground biomass ratio) has been widely used for estimating root biomass. However,there was a gap for the estimation of R∶S ratio in regional or large scale. Therefore,it is necessary to provide R∶S ratio data for a wide range of community types,which will improve the accuracy of carbon budget and root biomass estimate. Here the authors synthesized field biomass data from 113 sites and conducted regression analysis between R∶S ratio and environmental variables in Inner Mongolia temperate steppe,aiming to illustrate spatial variations of R∶S ratio and their regulating factors. The results showed that overall aboveground and belowground biomass of the temperate steppe averaged 135.3 and 775.2?g·m -2 ,respectively. R∶S ratio varied from 5.2 to 6.7 in different steppe,with median value 6.3. No significant relationships were found between R∶S ratio and mean annual temperature,soil water content,annual precipitation and steppe types.