蒙古高原草原土壤微生物量碳氮特征

沿着水分梯度采集了蒙古高原不同草原类型表层土壤样品 1 44个 ,分析了土壤微生物量C、N含量及其与年平均温度和降雨量的关系。结果表明 :蒙古高原草原土壤微生物量C、N与土壤有机C、全N、降雨量、温度均表现出了很好的相关性。微生物量C变化在5 1 7～ 797mgkg- 1之间 ,微生物量N变化在 1 1 0～ 1 1 8 6mgkg- 1之间。微生物量C∶N比变化在 5～ 9之间。土壤微生物量碳 (Cmic)占土壤有机碳 (Corg)的比例 (Cmic Corg)变化在 1 1 5 %～ 4 1 %之间 ,Cmic Corg与土壤有机C、全N、降雨量均成显著的负相关。土壤呼吸表现为草甸草原土壤 >典型草原 >荒漠草原 ,土壤呼吸与降雨量显著正相关 ,与温度显著负相关。呼吸熵 (QCO2 )与降雨量成二次抛物线关系。放牧对微生物量的影响与不同草原类型和放牧率有关。

SOIL MICROBIAL BIOMASS CARBON AND NITROGEN IN MONGOLIAN GRASSLAND

144 soil samples were collected along the moisture gradient in grassland region of the Mongolian Plateau for investigating soil microbial biomass C(C_mic)and N(Nmic),and their relations to annu al average temperature and rainfal.The results are as followings:Soil microbial biomass C and N showed significant correlations with soil organic carbon,total nitrogen,precipitation,and tempera ture.C_mic ranged from 51.7 to 797mg kg^-1;Nmic from 11 to 118.6mg kg^-1;C_mic:Nmic from 5 to 9,and C_mic/C_org from 1.15% to 4.1%.C_mic/C_org was correlative negatively with soil organic C, total N,and annual average precipitation.Soil respiration showed a decreasing trend:meadow steppe>typical steppe>desert steppe,correlating positively with precipitation,and negatively with temperature.The relationship of metabolic quot ient CO₂(Q_CO2) with precipitation can fit in quadratic equation.Effect of grazing on soil microbial biomass depends on grassland types and grazing intensity.