Relative importance of climatic and edaphic factors as drivers of plant δ¹⁵N along a longitudinal transect

ABSTRACT

Many studies have shown that climatic and edaphic factors influence the variations in nitrogen isotopes (δ¹⁵N) in terrestrial ecosystems. However, the relative importance of co-varying climatic and edaphic controls on plant δ¹⁵N remains somewhat unclear. To address this issue, regional-scale plant (L. chinensis) and soil samples were collected along a longitudinal transect across the temperate grasslands in northern China. The influences of climatic and edaphic factors on the plant δ¹⁵N were disentangled using the variable importance in projection (VIP) approach. We found that the climatic and edaphic variables explained 52.4% and 31.2%, respectively, of the variation in plant δ¹⁵N. The mean annual precipitation (MAP), soil N, and mean annual temperature (MAT) were the most important variables, but the soil water content (SWC), aridity index (AI), and soil clay content were also important variables. The soil pH and soil C: N ratios were identified as unimportant variables. Furthermore, a high-performance model for simulating plant δ¹⁵N values was constructed based on the important variables (VIP > 0.8). Further investigations should focus on the effects of the interaction between the climatic and edaphic variables on the N cycles in the temperate grasslands to provide more reliable predictions of plant δ¹⁵N.

KEYWORDS:

• Relative importance
• nitrogen isotopes
• climatic variables
• edaphic variables
• L. chinensis

Highlights

• The relative importance of climatic and edaphic controls on plant δ¹⁵N was systematically studied across the temperate grasslands in northern China.

• The influences of climatic and edaphic factors on the plant δ¹⁵N were disentangled using the VIP approach.

• Compared with the edaphic factors, the climatic factors explained more of the variation in the plant δ¹⁵N along the transect.

• The important information about the responses of the ecosystem’s N cycle to climatic and edaphic changes was provided in the temperate grasslands in northern China.

Acknowledgments

This work was supported by the Natural Science Foundation of Hunan Province (grant number 2020JJ4296). The authors would like to thank the editors and the anonymous reviewers for their valuable comments and suggestions on this paper. We also thank LetPub (www.letpub.com) for its linguistic assistance during the preparation of this manuscript.

Declaration of conflict interest statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Funding

This research was financed by the Natural Science Foundation of Hunan Province (No. 2020JJ4296).