Long-term reindeer grazing limits warming-induced increases in CO2 released by tundra heath soil: potential role of soil C quality

V�is�nen, Maria; Sjogersten Turner, Sofie; Large, David; Drage, Trevor; Stark, Sari

Abstract

© 2015 IOP Publishing Ltd. The current climate warming in the Arctic may increase the microbial degradation of vast pools of soil carbon (C); however, the temperature sensitivity of decomposition is often highly dependent on the quality of accumulated soil C. Grazing by reindeer (Rangifer tarandus L.) substantially affects the dominant vegetation and often increases graminoids in relation to dwarf shrubs in ecosystems, but the effect of this vegetation shift on the soil C quality has not been previously investigated. We analyzed the soil C quality and rate of microbially mediated CO2 release at different temperatures in long-term laboratory incubations using soils from lightly grazed dwarf shrub-dominated and heavily grazed graminoid-dominated tundra ecosystem. The soil C quality was characterized by solid-state cross-polarization magic angle spinning (CPMAS 13C NMR) spectroscopy, which showed a higher relative proportion of carbohydrate C under light grazing and higher relative proportion of aliphatic not-O-substituted C under heavy grazing. Initial measurements showed lower temperature sensitivity of the CO2 release in soils under light grazing compared with soil under heavy grazing, but the overall CO2 release rate and its temperature sensitivity increased under light grazing as the soil incubation progressed. At the end of incubation, significantly more carbohydrate C had been lost in soils under light grazing compared with heavy grazing. These findings indicate that there may be a link between the grazer-induced effects on soil C quality and the potential of soils to release CO2 to atmosphere. We suggest that vegetation shifts induced by grazing could influence the proportion of accumulated soil C that is vulnerable to microbial degradation under warming climate.

Citation

Väisänen, M., Sjogersten Turner, S., Large, D., Drage, T., & Stark, S. (2015). Long-term reindeer grazing limits warming-induced increases in CO2 released by tundra heath soil: potential role of soil C quality. Environmental Research Letters, 10(9), Article 094020. https://doi.org/10.1088/1748-9326/10/9/094020

• Journal Article Type: Article
• Acceptance Date: Sep 3, 2015
• Publication Date: Sep 16, 2015
• Deposit Date: Sep 15, 2017
• Publicly Available Date: Feb 5, 2019
• Journal: Environmental Research Letters
• Electronic ISSN: 1748-9326
• Publisher: IOP Publishing
• Peer Reviewed: Peer Reviewed
• Volume: 10
• Issue: 9
• Article Number: 094020
• DOI: https://doi.org/10.1088/1748-9326/10/9/094020
• Public URL: https://nottingham-repository.worktribe.com/output/1116560
• Publisher URL: https://iopscience.iop.org/article/10.1088/1748-9326/10/9/094020/meta
• PMID: 00036714
• Contract Date: Feb 5, 2019