青藏高原北部植物叶片碳同位素组成特征的环境意义

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（δ 13 C值）。研究结果表明，与其它地区相比，青藏高原北部植物叶片δ 13 C值相对较高，并且在海拔 4161 m的西大滩仍有植物δ 13 C值落在C4植物区，说明青藏高原的地理特殊性以及植物适应环境的策略。随海拔的升高，植物叶片δ 13 C值也随之升高，但变化程度具有物种的依赖性。唐古拉山南边植物叶片δ 13 C值明显高于北边植物叶片δ 13 C值，分析表明植物叶片δ 13 C值南北分布的这种格局主要是由降水的差异决定的。

THE ENVIRONMENTAL SIGNIFICANCE OF STABLE CARBON ISOTOPE COMPOSITION OF MODERN PLANT LEAVES IN THE NORTHERN PART OF THE TIBETAN PLATEAU

The Tibetan plateau is an important place for global changes studies owing to its ecological fragility and climatic sensitivity. The stable carbon isotope compositions in plant leaves can be used to provide information on the origin of carbon in soil organic matter and paleo-ecological evolutions due to the good relationship between the stable carbon isotope compositions and water use efficiency in plants or plant productivity to some extent. However, the knowledge about the pattern of spatial distribution of stable carbon isotope compositions of plant leaves in the Tibetan plateauis less available.
A total of 101 samples used in this study was collected from 13 sites in the northern part of the Tibetan plateau. The analyzed results show that foliar δ¹³C values in the northern Tibet , with an average of -26．89‰, were higher than other mountain regions in the world. Interestingly, C4 plants were found at the elevation of 4 161 m, where there was usually no C4 species distribution. The foliar δ¹³C values increased with increasing altitude, however, the amplitude of increase was dependent on species. Furthermore, compared with plants grown in the northern part of Tanggula mountains, there were significantly higher δ¹³C values at the southern part. The analysis revealed that the differences of δ¹³C values between the northern and southern part of Tanggula mountains were mainly ascribed to precipitation.