Herbivores suppress soil microbes to influence carbon sequestration in the grazing ecosystem of the Trans-Himalaya

Bagchi, Sumanta, Roy, Shamik ORCID: https://orcid.org/0000-0002-9916-5651, Maitra, Alakananda and Sean, Rubanpreet (2017) Herbivores suppress soil microbes to influence carbon sequestration in the grazing ecosystem of the Trans-Himalaya. Agriculture, Ecosystems & Environment, 239. pp. 199-206. ISSN 0167-8809

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Understanding factors that regulate carbon (C) pools is of high importance for offsetting greenhouse-gas emissions. Soils represent a vast C pool, whose size and stability are strongly influenced by land-use. Grazing, by native herbivores and livestock, is the predominant land-use across over 40% of the terrestrial surface and influences over 109 Mg of soil-C annually in the world’s dry regions. The interactions between plants, grazers, and soil microbes, is of critical importance for this soil-C pool. However, soil microbial responses to grazing, and associated feedbacks, remain poorly understood. Grazing management policies are unable to adequately accommodate key interactions that are important for effective ecosystem stewardship. After 10-yr of experimental herbivore-exclusion in the semiarid Trans-Himalayan ecosystem, we measured grazer effects on soil microbial abundance in n = 30 herbivore exclosures, each paired with an adjacent control plot using substrate-induced respiration, microbial-carbon, and microbial-nitrogen (SIR, MBC, MBN). We found that grazing reduced soil microbial biomass by 13–16%, over the course of the vegetation growing season. But, the strength and direction of grazer effects varied through time at different points in the growing season. Grazing also shifted fungal:bacterial ratio towards dominance by fungi which were more tolerant of periodic dry-down and seasonal fluctuations in soil moisture than bacteria. So, grazer influence on microbial abundance and community composition may collectively play crucial roles in net soil-C dynamics. But, this effect is constrained by environmental factors, such as moisture availability. The projected climatic trend in the Trans-Himalaya is towards progressively wetter conditions, and this may counter grazer effect on microbes, alter microbial communities, and ultimately impact potential soil-C storage. So, accounting for projected changes in precipitation, in addition to managing stocking density of herbivores, may also be crucial for these large soil-C pools.

Item Type: Article
Uncontrolled Keywords: sdg 15 - life on land ,/dk/atira/pure/sustainabledevelopmentgoals/life_on_land
Depositing User: LivePure Connector
Date Deposited: 02 Feb 2023 16:30
Last Modified: 06 Feb 2023 01:29
URI: https://ueaeprints.uea.ac.uk/id/eprint/90940
DOI: 10.1016/j.agee.2017.01.033

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