Soil δ15N is a better indicator of ecosystem nitrogen cycling than plant δ15N: A global meta-analysis

Liao, Kaihua; Lai, Xiaoming; Zhu, Qing

The nitrogen-15 (inline-formula15N) natural abundance composition (inline-formulaδ15N) in soils or plants is a useful tool to indicate the openness of ecosystem N cycling. This study aimed to evaluate the influence of the experimental warming on soil and plant inline-formulaδ15N. We applied a global meta-analysis method to synthesize 79 and 76 paired observations of soil and plant inline-formulaδ15N from 20 published studies, respectively. Results showed that the mean effect sizes of the soil and plant inline-formulaδ15N under experimental warming were inline-formula−0.524 (95 % CI (confidence interval): inline-formula−0.987 to inline-formula−0.162) and 0.189 (95 % CI: inline-formula−0.210 to 0.569), respectively. This indicated that soil inline-formulaδ15N had negative response to warming at the global scale, where warming had no significant effect on plant inline-formulaδ15N. Experimental warming significantly (inline-formulap<0.05) decreased soil inline-formulaδ15N in Alkali and medium-textured soils, in grassland/meadow, under air warming, for a 4–10-year warming period and for an increase of inline-formula>3inline-formulaC in temperature, whereas it significantly (inline-formulap<0.05) increased soil inline-formulaδ15N in neutral and fine-textured soils and for an increase of 1.5–3 inline-formulaC in temperature. Plant inline-formulaδ15N significantly (inline-formulap<0.05) increased with increasing temperature in neutral and fine-textured soils and significantly (inline-formulap<0.05) decreased in alkali soil. Latitude did not affect the warming effects on both soil and plant inline-formulaδ15N. However, the warming effect on soil inline-formulaδ15N was positively controlled by the mean annual temperature, which is related to the fact that the higher temperature can strengthen the activity of soil microbes. The effect of warming on plant inline-formulaδ15N had weaker relationships with environmental variables compared with that on soil inline-formulaδ15N. This implied that soil inline-formulaδ15N was more effective than plant inline-formulaδ15N in indicating the openness of global ecosystem N cycling.



Liao, Kaihua / Lai, Xiaoming / Zhu, Qing: Soil δ15N is a better indicator of ecosystem nitrogen cycling than plant δ15N: A global meta-analysis. 2021. Copernicus Publications.


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