青藏高原现生禾本科植物的δ13C与海拔高度的关系

文章通过分析青藏高原4种C3禾本科植物碳同位素值随海拔高度的变化,发现穗三毛(Trisetumspicatum),垂穗鹅观草(Roegnerianutans),紫花针茅(Stipapurpurea),垂穗披碱草(Elymusnutans)的碳同位素值随海拔高度增加而变重的趋势明显,平均每增高1km变重1.37‰,其中Trisetumspicatum和Roegnerianutans的碳同位素值随海拔高度增加而变重的趋势更为显著。研究认为温度和大气CO₂分压是引起C3植物碳同位素值随海拔高度变化的主要因素。另外,研究发现一些C4植物的生长高度可以达到海拔4000m以上,最高可达海拔4520m。

ALTITUDINAL TRENDS OF STABLE CARBON ISOTOPE COMPOSITION FOR POECEAE IN QINGHAI-XIZANG PLATEAU

In a global survey of δ¹³C values of plants collected from a wide range of altitudes, spanning many taxonomic and physiognomic groups as well as a wide geographic range, C.Korner et al . found that δ¹³C values increased with altitude. Other researchers found that δ¹³C values in single species increase with altitude. However, Most of these studies were carried out on a very restricted range of sites. So far, relatively few systematic studies have addressed how δ¹³C values in single species growing in a complicated environment like Qinghai Xizang Plateau change with altitude. In this survey stable carbon isotope compositions are determined on leaves of Poaceae plants (Trisetum spicatum, Roegneria nutans, Stipa purpurea, Elymus nutans) sampled along a 2 000 km transect on Qinghai Xizang Plateau of China. δ¹³C values for all samples increase with altitude generally, the mean δ¹³C increase with altitude is 1.37‰/km. Carbon isotope ratios of Trisetum spicatum and Roegneria nutans increase significantly with altitude. The result of linear analyses indicates that temperature and CO₂ partial pressure are the major factors causing the δ¹³C ratios of C₃ plants to increase with altitudes. In this study, we sampled C₄ plants: Chloris virgata,Eragrostis ferruginea,Eragrostis nigra,Arundinella yunnanensis,Orinus thoroldii,Pennisetum centrasiaticum,Atriplex centralasiatica, Salsola ruthenica and found some of them distributed above 4 000m, even reached 4 520m.