Altitudinal trends of leaf δ13C follow different patterns across a mountainous terrain in north China characterized by a temperate semi‐humid climate

Many studies have documented that the δ13C values of plants increase with altitude both on a global scale and locally in humid climates, while in semi-arid areas the opposite trend has been found. The study reported herein was conducted in a mountainous area of China characterized by a temperate semi-humid climate. The δ13C values of C3 species do not exhibit a consistent variation along an altitudinal gradient and the observations suggest that the pattern of increasing δ13C with altitude cannot be generalized. In the study area, in addition to environmental factors such as changing air pressure and light, the interaction between temperature and plant water balance determines the δ13C-altitude variations in C3 plants. The δ13C of the leaves of C4 plants is found to increase with altitude with a mean gradient of 0.9‰/km. The altitudinal trend of C4 plants is attributed to the combined influences of water availability and other factors rather than temperature. Copyright © 2010 John Wiley & Sons, Ltd.