目前, 在中国区域关于植物碳稳定性同位素组成(δ¹³C)已经有了很多的研究, 同时, δ ¹³C作为植物水分利用效率(WUE)的替代指标, 得到了越来越广泛的应用。而这些研究多集中在站点或小的区域尺度, 那么在整个中国区域尺度上, δ¹³C能否作为植物WUE的替代指标值得探讨。该文通过对文献资料的收集整理, 研究了中国区域187个采样点478种C₃植物叶片的δ¹³C, 统计分析结果表明δ¹³C的变化范围为-33.50‰- -22.00‰, 均值为-(27.10 ± 1.70)‰。在乔木、灌木和草本3种不同的生活型间, 叶片δ¹³C的差异达到极显著水平, 其中以草本的δ¹³C最高, 乔木最低, 这与在站点或小的区域尺度上的研究结果不同。对不同系统发育类型的植物而言, 种子植物的δ¹³C极显著地大于蕨类植物; 祼子植物与被子植物间的差异未达到显著水平; 单子叶植物极显著地大于双子叶植物。叶片δ¹³C值随经度的变化没有明显的规律, 但是随纬度的增加, δ ¹³C极显著地升高。随年均温度和年均降雨量的降低, 叶片δ¹³C值极显著升高。年均降雨量与δ¹³C间的这种极显著的负相关关系, 与WUE和降水量间的关系一致, 这表明在大的区域尺度上, δ¹³C可以作为植物WUE的指示指标。

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.