摘要：This study aimed to make a reasonable use of forests in Liaoning province. By using C-isotope (leaf 13 C value) as an index for long-term water-use efficiency (WUE), we evaluated the WUE of threetypical afforestation tree species, namely, Pinus sylvestris var. mongolica, Pinus tabulaeformis, andQuercus mongolica. We then determined their response to environmental factors, such as annualaverage precipitation, annual average air temperature, altitude, and soil nutrient. Results of linearregression analysis indicate that (1) the 13 C values of the three tree species were -30.37‰ to -23.51‰, and the 13 C values in their leaves decreased with the longitudes. (2) The 13 C values in theleaves of the three tree species were significantly influenced by the annual average precipitation andaltitude, i.e., the 13 C values decreased significantly with the annual average precipitation and increasedwith altitude, although the 13 C values in their leaves were less influenced by the annual average airtemperature. (3) Except soil nutrients, such as calcium contents, which showed no obvious relationshipwith 13 C of Q. mongolica, P. sylvestris and P. tabulaeformis were significantly affected by soilnutrients. This work was the first to investigate the WUE of the three tree species mentioned above.This study also explored the main factors influencing WUE. Overall, our findings may facilitate futurescientific studies on WUE based on 13 C, and these studies will be beneficial to environmental protection.
