青藏高原北部植物叶片碳同位素组成的空间特征

测定了青藏高原北部13个地点101份草本植物叶片碳同位素组成(δ¹³C值), 结果发现, 植物叶片δ¹³C值的分布范围在-29.2‰～-23.8‰之间, 平均值约为-26.89‰, 明显低于全球高海拔植物叶片δ¹³C值(-2.6‰) ; 而植物叶片δ¹³C值随海拔和经、纬度的变化趋势与其它同类报道相似:随着海拔的升高和经、纬度的降低, 植物叶片δ¹³C值呈现升高趋势. 叶片δ¹³C值也随土壤含水量和土壤温度的变化而变化:土壤含水量越高, 土壤温度越低, 植物叶片δ¹³C值越小, 但它们之间的相关关系不具统计学意义. 初步分析表明, 大气压力 (CO₂分压)和温度的协同变化导致了叶片δ¹³C值随着海拔变化的分布格局, 而温度和相对湿度的变化是引起叶片δ¹³C值的经、纬度效应的主要因子.

Spatial Distribution of Stable Carbon Isotope Compositions of Plant Leaves in the North of the Tibetan Plateau

Tibetan Plateau is an important position for studying the global changes due to its ecological vulnerability and climatic sensitivity. The stable carbon isotope compositions in plant leaves can be used to provide information of original carbon in soil organic matter and paleo-ecological evolutions, based on the good relationship between the stable carbon isotope compositions and water use efficiency in plants or plant productivity to some extent. However, the pattern of spatial distribution of stable carbon isotope compositions of plant leaves in the Tibetan Plateau is less studied. The aim of this study is to determine the effects of altitude, latitude and longitude on foliar δ¹³C values and their mechanisms;A total of 101 samples used in this study were collected from 13 sites in the northern part of the plateau. The analyses show that foliar δ¹³C, with an average of -26.89‰, ranged from^-29.52‰ to -23.85‰. The δ¹³C increased with increasing altitude and decreasing latitude and longitude. There was a statistically insignificant effect of soil water contents and soil temperature on the foliar δ¹³C. These results suggest that altitude effect of foliar δ¹³C was mainly ascribed to temperature and atmospheric pressure (the partial pressure of CO₂), while temperature and relative humidity were possibly responsible for the latitude and longitude trends of foliar δ¹³C.