Abstract:

Aims There have been many studies of carbon isotope composition (δ¹³C) of C₃ plants in China, and δ¹³C has been widely used as an index of water use efficiency (WUE); however, most studies focused on single sites or small regions. Therefore, our objective was to study the spatial pattern of δ¹³C, the relationships between δ ¹³C and climate factors and whether δ ¹³C can represent WUE in large regions.
Methods We obtained leaf δ ¹³C for 478 C₃ species from 187 sites in China based on the literature.
Important findings The range of δ¹³C was from -33.50‰ to -22.00‰, and the mean was -(27.10‰ ± 1.70)‰. There were significant differences among δ¹³C of grasses, shrubs and trees, with grasses having the highest value and trees the lowest. The result was different from studies in single sites and small regions. For different phylogenic plants, δ ¹³C of seed plants was significantly higher than ferns, the difference between gymnosperms and angiosperms was not statistically significant and monocotyledons had significantly higher values than dicotyledons. Leaf δ ¹³C had irregular variation with increasing longitude, but significantly increased with increasing latitude. Leaf δ ¹³C significantly increased with mean annual temperature and decreasing mean annual precipitation. The relationship between δ ¹³C and precipitation was similar to that of WUE and precipitation, so we conclude that δ ¹³C of C₃ plants can be used as an index of WUE in large regions as well as in single sites or small regions.

Key words: C₃ plant, life-form, precipitation, stable isotope, water use efficiency