Loss of grazing by large mammalian herbivores can destabilize the soil carbon pool

Naidu, Dilip G. T., Roy, Shamik ORCID: https://orcid.org/0000-0002-9916-5651 and Bagchi, Sumanta (2022) Loss of grazing by large mammalian herbivores can destabilize the soil carbon pool. Proceedings of the National Academy of Sciences, 119 (43). ISSN 0027-8424

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Grazing by mammalian herbivores can be a climate mitigation strategy as it influences the size and stability of a large soil carbon (soil-C) pool (more than 500 Pg C in the world’s grasslands, steppes, and savannas). With continuing declines in the numbers of large mammalian herbivores, the resultant loss in grazer functions can be consequential for this soil-C pool and ultimately for the global carbon cycle. While herbivore effects on the size of the soil-C pool and the conditions under which they lead to gain or loss in soil-C are becoming increasingly clear, their effect on the equally important aspect of stability of soil-C remains unknown. We used a replicated long-term field experiment in the Trans-Himalayan grazing ecosystem to evaluate the consequences of herbivore exclusion on interannual fluctuations in soil-C (2006 to 2021). Interannual fluctuations in soil-C and soil-N were 30 to 40% higher after herbivore exclusion than under grazing. Structural equation modeling suggested that grazing appears to mediate the stabilizing versus destabilizing influences of nitrogen (N) on soil-C. This may explain why N addition stimulates soil-C loss in the absence of herbivores around the world. Herbivore loss, and the consequent decline in grazer functions, can therefore undermine the stability of soil-C. Soil-C is not inert but a very dynamic pool. It can provide nature-based climate solutions by conserving and restoring a functional role of large mammalian herbivores that extends to the stoichiometric coupling between soil-C and soil-N.

Item Type: Article
Additional Information: Data, Materials, and Software Availability: The data are available through the Zenodo repository (https://doi.org/10.5281/zenodo.7071575) (67), and the computer code is provided in SI Appendix. Funding Information: D.G.T.N. was supported by a graduate fellowship from the Divecha Centre for Climate Change; S.R. was supported by a graduate fellowship from Council for Scientific and Industrial Research-India; S.B. was supported by Ministry of Human Resource Development-India. This work was funded by Department of Science and Technology - Fund for Improvement of S&T infrastructure, Department of Science and Technology - Science and Engineering Research Board, Indian Institute of Science - Space Technology Cell, Ministry of Environment, Forests, and Climate Change, and by Department of Biotechnology - Indian
Uncontrolled Keywords: biogeochemistry,carbon cycle,path analysis,phase-space analysis,stoichiometry
Faculty \ School: Faculty of Science > School of Biological Sciences
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Depositing User: LivePure Connector
Date Deposited: 08 Feb 2023 09:30
Last Modified: 08 Feb 2023 09:30
URI: https://ueaeprints.uea.ac.uk/id/eprint/91074
DOI: 10.1073/pnas.2211317119

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