实测了青藏高原植被样带 2 2个地区不同植被类型的地上部分生物量并进行了格局分析。对于未受人为干扰的以常绿阔叶林为基带的亚高山天然植被 ,随着海拔升高 ,地上生物量呈递增趋势 ,在一定海拔高度达最大 ,海拔继续升高地上生物量则迅速下降。这一垂直分异规律在一定程度上反映了全球地带性森林植被最大生物量分布的纬向分异性。基于Weber定律的回归分析表明 ,地上生物量与水热因子的相关关系可用Logistic函数拟合 ,1月平均气温、7月平均气温、年平均气温、年降水量及其组合因子可解释高原植被样带地上生物量变化的 2 8%～5 3% ,其中年降水量及其同年平均气温的组合与地上生物量的相关性最高 (R2 为 0 .4 6～ 0 .5 3,p <0 .0 0 1)。但是 ,年降水量和平均气温的变化不足以解释西藏色齐拉山暗针叶林具有最高的地上生物量。我们认为 ,自然植被地上部分生物量的分布格局受到更为复杂的气候因子的制约 ,例如太阳辐射、湿度、风、水分和能量平衡等。

We measured aboveground live_biomass density (ABD) in 22 sites along the Tibetan Alpine Vegetation Transects (TAVT ) for different vegetation types including forests, shrublands and grasslands. Pattern analysis indicated that ABD of natural vegetation in the mountain areas increased from lower to higher altitudinal zones until the maximumwas reached at some optimum elevation level and then declined as the altitude continued to increase. We believe that the altitudinal patterns to some extent reflect the latitudinal differences of maximum biomass in global forests. Regressions of transformed data based on the Weber. slaw revealed that January, July and annual mean temperatures and annual precipitation, singly or in combination, accounted for 28%_53% of the variation in ABD along theTAVT where annual precipitation and its combinationwith annual mean temperature had the highest relationship to ABD ( R2=0.46_0.53, p<0.001). The relationships between ABD and the climatic factors could be expressed as logistic equations with amaximumABD of 1 500Mg DW#hm-2. However, the variations in annual precipitation and mean temperatures could not explain the highest ABD in the alpine fir forest in SergyemlaMountains because ABD distribution patterns of natural vegetation can be limited by additional climatic factors such as solar radiation, wind, moisture and related water/ energy balances.