Functional substitutability of native herbivores by livestock for soil carbon stock is mediated by microbial decomposers. Issue 8 (2nd February 2023)

• Record Type: Journal Article
• Authors: Roy, Shamik; Naidu, Dilip G. T.; Bagchi, Sumanta
• Is Part Of: Global change biology. Volume 29:Issue 8(2023)
• Page Start: 2141
• Page End: 2155
• Publication Date: 2023-02-02
• Subjects: carbon hoofprint -- carbon use efficiency -- ecosystem disservice -- grassland -- microbiome rewilding -- restoration -- soil microbial enzymes -- tetracycline; Climatic changes -- Environmental aspects -- Periodicals; Troposphere -- Environmental aspects -- Periodicals; Biodiversity conservation -- Periodicals; Eutrophication -- Periodicals; 551.5
• DOI: 10.1111/gcb.16600
• Languages: English
• ISSNs: 1354-1013

Abstract

Abstract: Grazing by large mammalian herbivores impacts climate as it can favor the size and stability of a large carbon (C) pool in the soils of grazing ecosystems. As native herbivores in the world's grasslands, steppes, and savannas are progressively being displaced by livestock, it is important to ask whether livestock can emulate the functional roles of their native counterparts. While livestock and native herbivores can have remarkable similarity in their traits, they can differ greatly in their impacts on vegetation composition which can affect soil‐C. It is uncertain how these similarities and differences impact soil‐C via their influence on microbial decomposers. We test competing alternative hypotheses with a replicated, long‐term, landscape‐level, grazing‐exclusion experiment to ask whether livestock in the Trans‐Himalayan ecosystem of northern India can match decadal‐scale (2005–2016) soil‐C stocks under native herbivores. We evaluate multiple lines of evidence from 17 variables that influence soil‐C (quantity and quality of C‐input from plants, microbial biomass and metabolism, microbial community composition, eDNA, veterinary antibiotics in soil), and assess their inter‐relationships. Livestock and native herbivores differed in their effects on several soil microbial processes. Microbial carbon use efficiency (CUE) was 19% lower in soils under livestock. Compared to native herbivores, areas used by livestock contained 1.5 kg C m −2 less soil‐C. Structural equation models showed that alongside the effects arising from plants, livestock alter soil microbial communities which is detrimental for CUE, and ultimately also for soil‐C. Supporting evidence pointed toward a link between veterinary antibiotics used on livestock, microbial communities, and soil‐C. Overcoming the challenges of sequestering antibiotics to minimize their potential impacts on climate, alongside microbial rewilding under livestock, may reconcile the conflicting demands from food‐security and ecosystem services. Conservation of native herbivores and alternative management of livestock is crucial for soil‐C stewardship to envision and achieve natural climate solutions. Abstract : Livestock have become the dominant grazers around the world, as they progressively replace native herbivores. It remains unclear whether livestock can match soil‐C services provided by native herbivores. And if so, then to what extent? We find that livestock could attain only three‐fourths of soil‐C stocks compared to native herbivores. This was due to lower soil microbial carbon use efficiency under livestock, and veterinary use of antibiotics which eventually enter the soil to alter microbial communities. Sequestering antibiotics alongside microbial rewilding may help livestock production systems to emulate the ecosystem services provided by native herbivores.