Patterns of soil and plant nitrogen isotope composition and their relationships with climate factors in Xilingol League, Inner Mongolia, China

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.

Keywords:

• mean annual precipitation
• mean annual temperature
• plant δ¹⁵N
• soil δ¹⁵N
• temperate grasslands

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.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

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).

Notes on contributors

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.