Carbon isotope composition of plants along altitudinal gradient and its relationship to environmental factors on the Qinghai-Tibet Plateau

Abstract

Distribution pattern of δ 13 C values of plateau plants and their responses to environment along altitudinal gradients were in- vestigated. In the growing season of 2003 (June- August), stable carbon isotope ratios (δ 13 C) of 174 plant samples belonging to 89 species of 20 families and 58 genera along the gradient 2800- 4400 m (above sea level) was studied in six sites on the east edge of Qinghai-Tibet Plateau. The results indicated that the range of δ 13 C values of plants is narrow from -30.2‰ to -25.2‰, which means that none of the species examined belonged to C4 photosynthetic pathway and all of these species performed C3 photosynthetic pathway. The average δ 13 C values of plants at 6 sites were positively correlated to altitude (r = 0.974, P 0.05) as well as the sunlight duration(r = 0.630, P> 0.05).