Grazing practices affect the soil microbial community composition in a Tibetan alpine meadow

Abstract

Grazing is the primary land‐use activity on the Tibetan Plateau and can affect soil microbes and their function through aboveground vegetation removal, animal trampling, and manure deposition. Two distinct grazing systems (i.e., winter grazing [WG] and annual grazing [AG]) dominate on the Tibetan Plateau, but their effects on soil microbes have rarely been assessed. Taking advantage of a 5‐year field experiment that controlled timing and density of grazers via fence exclosures, we examined impacts of different grazing practices on the biomass, diversity, and composition of the soil microbial community in a Tibetan alpine meadow. On the basis of high‐throughput sequencing, we found that grazing had no significant effects on bacterial and fungal α‐diversities but altered their community compositions. Although total soil carbon (TC), total soil nitrogen (TN), and carbon/nitrogen (C/N) were related to both bacterial and fungal community compositions, plant shoot biomass only correlated with bacteria, and soil pH and moisture significantly influenced fungi under grazing. Also, grazing altered plant community composition but did not lead to corresponding changes in bacterial or fungal community composition. Moreover, grazing practices affected the relative abundance of specific bacterial and fungal taxa, reducing Actinobacteria but increasing Basidiomycete fungi in WG. Soil TC and TN were higher, and the soil microbial community was more stable in AG than WG, likely due to more stable litter inputs in AG. Together, these results showed that AG was less disruptive to soil microbes, suggesting that AG may provide a viable option for sustainable utilization and conservation of these fragile alpine systems.

Peer Review #1 of "Response of arbuscular mycorrhizal fungal community in soil and roots to grazing differs in a wetland on the Qinghai-Tibet plateau (v0.1)"

“…Grazing significantly affected the AM fungal community composition in soil, in consistent with some previous studies reported in desert steppe and grassland ecosystems (Murray, Frank & Gehring, 2010;Bai et al, 2013). Grazing may influence the AM fungal community composition by changing soil properties through animal trampling and fecal deposition (McNaughton, Banyikwa & McNaughton, 1997;Yang et al, 2019). For example, animal trampling may make the soil tight and alter soil bulk density (Kauffman, Thorpe & Brookshire, 2004;Byrnes et al, 2018), thereby influencing AM fungal community (Yang et al, 2018).…”

“…Besides, grazing may cause changes in AM fungal richness and community composition in plant roots and surrounding soil (Bai et al, 2013;Yang et al, 2013). However, these responses are environmentally dependent and habitatsensitive and may be influenced by soil characteristics and dynamics (Ren et al, 2018;Yang et al, 2019). This study represents the first one to analyze AM fungal responses to grazing in wetland ecosystems.…”

Grazing significantly increases root shoot ratio but decreases soil organic carbon in Qinghai‐Tibetan Plateau grasslands: A hierarchical meta‐analysis

“…Studies found that grazing significantly influenced the structure and function of grassland ecosystems (Yang et al, 2019;Zhuang, Zhang, & Li, 2019). In the current study, grazing decreased both the plant production and soil carbon and nitrogen contents of QTP grasslands ( Figure 5).…”

Temporal and spatial succession and dynamics of soil fungal communities in restored grassland on the Loess Plateau in China

“…They are often presumed to be more important in natural ecosystems than in intensively managed systems that are mostly dominated by bacteria (Franciska T. de Vries, Hoffland, Nvan, Brussaard, & Bloem, ). The communities of soil bacteria and fungi are correlated with different soil edaphic factors under two distinct grazing systems dominating on the Tibetan Plateau (Yang et al, ). In particular, strong interactions occur between soil fungal diversity and edaphic variables in natural ecosystems (Zhang, Dong, et al, ), and soil fungi may be greater affected by the process of woody plant encroachment compared with soil bacteria (Hollister, Schadt, Palumbo, James Ansley, & Boutton, ).…”