Abstract: In order to explore the influences of environmental factors on belowground biomass and biomass allocation in grassland ecosystems and to test ‘functional equilibrium hypothesis’, the vertical distribution of belowground biomass and the relationship of belowground biomass (BGB) with belowground biomass, as well as the patterns of BGB and the response of belowground/aboveground biomass ratio (B/A) to environmental factors were examined in the central Inner Mongolia grassland along with thermal and moist gradients. Results showed that belowground biomass mainly concentrated in topsoil layer and had significant correlation with aboveground biomass. Belowground biomass had positive response to annual mean precipitation, organic carbon and total nitrogen, whereas negative response to annual mean temperature. Precipitation, besides the effect of soil features, was the most prominent factor that influenced the geographic disparity of belowground biomass. Additionally, the effect of total nitrogen on B/A was significantly positive which disagreed with the Functional Equilibrium Hypothesis. Those results indicated that the effects of environmental factors on B/A were rather complicated, and suggested further integrated study in physiological and ecological traits of grassland plants.

Key words: Belowground biomass, Biomass allocation, Below-aboveground biomass ratio, Climatic factors, Soil environmental factors

摘要： 为探究环境因子对草原地下生物量与生物量分配的影响以及验证功能平衡假说,沿水热变化梯度通过采样获取内蒙古中部草原的生物量,分析了地下生物量的垂直分布及其与地上生物量的关系,采用回归和结构方程模型的方法探讨了地下生物量与地下地上生物量比对环境因子的响应规律。结果表明:地下生物量主要分布在土壤表层,地下与地上生物量成显著正相关;地下生物量对年均降水量、土壤有机碳和全氮为正响应,对年均温和土壤pH值则为负响应;其中,降水量是导致地下生物量差异的主要因子;土壤环境也具有重要的作用。土壤全氮与地下地上生物量比之间的显著正响应关系与功能平衡假说不符。综上所述表明,环境因子对地下地上生物量比产生的影响十分复杂,需要进一步结合植物生理和生态学特性等多方面的综合分析才能得出可靠的结论。

关键词: 地下生物量, 生物量分配, 地下地上生物量比, 气候因子, 土壤环境因子