Abstract
Background: Plant and soil nitrogen stable isotope (δ15N) can integrate several fundamental biogeochemical processes in ecosystem nitrogen dynamics, and reflect characteristics of ecosystem nitrogen cycling.
Aims: We investigated how climate change influenced plant-soil nitrogen cycling by relating soil δ15N, plant δ15N and Δδ15N (difference between soil and plant δ15N) with climatic factors.
Methods: Field investigation was conducted in temperate grasslands in Inner Mongolia during August 2015. Plant δ15N, soil δ15N and Δδ15N were determined, and their relationships with climatic factors were examined by simple regression analyses and general linear models.
Results: Soil δ15N was significantly higher than plant δ15N, and there was a positive linear correlation between them. Soil and plant δ15N were negatively related with mean annual precipitation (MAP) and positively with mean annual temperature (MAT); conversely, Δδ15N was positively related with MAP and negatively with MAT.
Conclusion: Soil δ15N was dominantly controlled by MAT, while it was MAP for plant δ15N. Climate factors influenced plant δ15N not only through their effects on soil nitrogen dynamics but also strategies of plant nitrogen acquisition. Thus, compared with plant δ15N, soil δ15N can more accurately reflect soil nitrogen dynamics, while plant δ15N may integrate soil nitrogen dynamics and plant nitrogen acquisition.
Acknowledgements
The research was funded by the National Natural Science Foundation of China (grant no. 31400413, 41571455, 51578115), Fundamental Research Funds for the Central Universities of China (grant no. N130301001, N160102001), the Doctoral Startup Foundation of Liaoning Province (grant no. 20141017). We thank the central physicochemical laboratory of the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences for isotope determining.
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No potential conflict of interest was reported by the authors.
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Chengwu Song
Yongchun Zhou is a research ecologist interested in stable isotope ecology and global climate change. Haibo Li is a research ecologist interested in environment bio-remediation. Xilei Cheng is a research ecologist interested in environment ecology. Xinyang Xu is a research ecologist interested in Environment ecology. Hongli Zhang is a M. Phil. student whose research interest is focused on stable isotope ecology. Wenbo Zhang is a M. Phil. student whose research interest is focused on stable isotope ecology. Lin Liu is a researcher interested in ecologically sustainable development. Yinghua Li is a research ecologist interested in environment bio-remediation. Chengwu Song is a M. Phil. student whose research interest is focused on environment bio-remediation.