内蒙古温带草原的根冠比及其影响因素

R∶S Ratios of Temperate Steppe and the Environmental Controls in Inner Mongolia

温带草地大部分生物量分布在地下,地下生物量在草地生态系统碳循环中起着重要作用。利用根冠比(R∶S)和地上生物量来估算地下生物量是目前常用的方法,但目前缺乏根冠比的数据。本研究利用内蒙古温带草原的生物量实测数据,分析了R∶S及其影响因素。结果显示(1)内蒙古温带草原地上和地下生物量分别为135.3、775.2g.m-2,不同草原类型生物量差异显著,荒漠草原、典型草原和草甸草原的地上生物量分别为56.6、133.4和196.7g.m-2,地下生物量分别为301.0、688.9和1385.2g.m-2。(2)研究区3种草原类型的R∶S差异较小,荒漠草原、典型草原和草甸草原R∶S中值分别为6.7、5.3和5.2,总体上,内蒙古温带草地的R∶S为6.3。(3)R∶S与年均温、年降水和土壤含水率之间没有显著相关关系。

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.