Electronic supplementary material from Precipitation is the main factor affecting the variation of foliar nitrogen isotope composition in two leguminous shrub species of northwestern China
2018-07-11T12:46:29Z (GMT) by
An increase in foliar nitrogen isotope composition (δ<sup>15</sup>N) with decreasing precipitation has been shown to occur widely in non-N<sub>2</sub>-fixing plant species. However, similar patterns have not been identified in N<sub>2</sub>-fixing species. Here, we tested the relationships of foliar δ<sup>15</sup>N with local environmental factors and leaf properties in two leguminous shrub species (<i>Caragana korshinskii</i> and <i>Caragana liouana</i>) sampled from 30 populations. Results indicated that the mean annual precipitation (MAP) primarily accounted for the variation of foliar δ<sup>15</sup>N in the two species. Further analysis revealed strong negative correlations between foliar δ<sup>15</sup>N and MAP within and across species. These results suggest that the foliar δ<sup>15</sup>N of leguminous shrub species also shift along precipitation gradients, which augments our understanding of the relationships between foliar δ<sup>15</sup>N and climatic factors.