Abstract: In Chinese grassland transect which across Inner Mongolia and Qinghai-Tibet Plateau, 132 sampling plots were set up, and 329 leaf samples which belong to 138 species were collected. Based on the chemical analyses of plant samples, the spatial pattern of leaf nitrogen and phosphorus elements and its related to climatic factors were analyzed. The purpose of the study was to provide the basis for the researches of grassland C, N and P element cycles and grassland ecosystem response to global climate change, and also provide basic data for ecological model. Results showed that plant N and P contents in Qinghai-Tibet Plateau region were higher than those in Inner Mongolia area. The N content of plant leaf decreased, whereas P content and N/P ratio did not change significantly with the increase of mean annual temperature. The N and P contents of plant leaf slightly increased, while N/P had no obvious change with the increase of mean annual precipitation. These results proved a temperature -plant physiological hypothesis, and also supported a soil substrate age hypothesis and a growth rate hypothesis. However, The pattern, rule and mechanism of N and P in grassland vegetation needed further study.

Key words: Grassland plant, N, P, Spatial pattern, Climate factor

摘要： 在横穿内蒙古和青藏高原的中国草地样带中，设置了132个采样样地，采集到138种、329个植物叶片样品。在对植物样品进行化学元素分析的基础上，分析了植物叶片氮磷元素空间格局及其与气候因子的关系，试图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，同时也为相关生态学模型提供基础数据。结果表明：青藏高原地区植物N，P含量均高于内蒙古地区。随着年均温的增加，植物叶片N元素含量呈降低趋势，P元素含量和N/P变化不明显；随着年均降水量的增加，植物叶片N，P元素含量均略呈增加的趋势，而N/P变化不明显。上述研究结果验证了温度-植物生理假说（TPPH），同时，还支持土壤年龄假说和生长速率假说。然而，地带性气候因子对植物叶片N，P元素变异的解释率并不高，这表明草地植被N，P元素变化的格局、规律和机制仍需进一步深入研究。

关键词: 草地植物, 氮, 磷, 空间格局, 气候因子