干旱区生态环境知识资源中心

Understanding the mechanisms of how environmental factors limit species distribution along environmental gradients is a central question in ecology. This study aimed to understand species acclimation in view of photosynthetic parameters in an arid mountainous region. We measured some photosynthetic parameters and light and CO2 photosynthesis response curves for all plant communities with seven dominant species in 13 sites along an elevation gradient in the Qilian Mountains in arid northwestern China. ’I he results showed that species in xerothermic environments had low maximum rate of carboxylation (Vcmax) (14.5 mu mol m(-2) s(-1)) and maximum rate of electron transport (Jmax) (22.7 mu mol m(-2) s(-1)), high light compensation points (60.0 mu mol m(-2) s(-1)) and light saturation points (1150.7 mu mol m(-2) s(-1)), high dark respiration rates (5.3 mu mol m(-2) s(-1)), and high maximum photosynthetic rates (Amax) (18.1 mu mol m(-2) s(-1)) compared with species in mesic environments. Photosynthesis parameters did not vary with temperature, precipitation, and altitude in different communities dominated by the same species, Picea crassifolia. However, some photosynthesis parameters varied with temperature, precipitation, and altitude in communities dominated by species other than spruce at different elevations. Selected photosynthesis parameters could be used to measure species adaptation to environmental gradients in arid mountain regions.