中文摘要：

在横穿内蒙古和青藏高原长达4000 km的中国草地样带中，设置了132个采样样地，采集到120个植物根系样品，对样品进行了化学元素测定。在此基础上，分析了植物根系N、P元素的基本特征，空间分布格局以及其与气候因子的关系。研究结果表明，草地植物根系P元素含量的变异系数大于N 元素，而青藏高原地区植物根系N、P含量的变异系数均高于内蒙古地区。植物根系N和P元素含量之间的相关性明显，同时，P 与N／P 的相关关系比N与N／P的相关关系更为明显。在草地类型上，高寒草甸类植物根系的N含量最低，而温性草原最高。在与生境因子的关系上，草地植物根系N含量具有随着海拔增加而降低，随年均温的增加而增加，随年均降水量的增加而降低的趋势，但其相关程度都较弱，这说明植物根系的元素含量可能受到植被组成、环境因素等多方面的综合影响。对草地植物根系元素化学计量学特征的研究，有助于为全球气候变化条件下草地的C、N、P 元素循环研究以及草地生态系统对全球气候变化的响应和适应研究提供依据，同时也可为相关生态模型提供基础数据。

英文摘要：

120 plant root samples were collected from 132 sample plots along a 4000 km Chinese grassland tran-sect from Inner Mongolia to the Qinghai-Tibet Plateau.Plant root N and P content and their relationship to geographical and climate factors were analyzed.The aims are to understand grassland plant root stoichiometry for these two elements,in order to provide a basis for studies of grassland C,N,and P circulation under condi-tions of global climate change,to study the grassland ecosystem responses to global climate change.In addi-tion,the research may provide fundamental data for relevant ecologic models.The coefficient of variation for P content is higher than that of N in plant roots.The coefficients of variation of both P and N contents in plant roots collected from the Qinghai-Tibet area are higher than those for samples collected from the Inner Mongo-lia area.There is significant correlation between N and P levels in plant roots.In addition,the correlation be-tween P and N/P is more significant than the correlation between N and N/P.From the grassland type perspec-tive,highest and lowest values for the N content of plant root were both found in samples from the temperate steppe.From the perspective of correlation between biological and environment factors,plant root N content decreased with increasing altitude,increased with increasing of annual mean temperature,and decreased with increasing of annual precipitation.However,these correlation relation are not strong.Thus it indicate that the element content in plant root may be affected by various combination factors such as vegetation composition and environmental factors.