Reduced microbial stability in the active layer is associated with carbon loss under alpine permafrost degradation

Abstract

Permafrost degradation may induce soil carbon (C) loss, critical for global C cycling, and be mediated by microbes. Despite larger C stored within the active layer of permafrost regions, which are more affected by warming, and the critical roles of Qinghai-Tibet Plateau in C cycling, most previous studies focused on the permafrost layer and in high-latitude areas. We demonstrate in situ that permafrost degradation alters the diversity and potentially decreases the stability of active layer microbial communities. These changes are associated with soil C loss and potentially a positive C feedback. This study provides insights into microbial-mediated mechanisms responsible for C loss within the active layer in degraded permafrost, aiding in the modeling of C emission under future scenarios.

Variations and Mutual Relations of Vegetation–Soil–Microbes of Alpine Meadow in the Qinghai-Tibet Plateau under Degradation and Cultivation

“…In addition, AAG and IAM covered more common bacteria regardless of taxonomic units, indicating a possibly improving microbial environment in the AAG (Table 2). Microbial functional genes are more sensitive to environmental disturbance [50,51]. Consistent with the previous studies, Chemoheterotrophy, aerobic chemoheterotrophy, and nitrification were the dominant functional bacteria groups under degradation and cultivation (Figure 5) [9,13].…”

Aridity Threshold Induces Abrupt Change of Soil Abundant and Rare Bacterial Biogeography in Dryland Ecosystems

“…Equally important, we found that community assembly exhibited a distinct pattern of nonlinear responses to increasing aridity. Although the coexistence networks based on Spearman correlation may be biased for compositional data (compared with SparCC) ( 60 ), the networks can still meet the overall trend of coexistence relationships ( 61 – 63 ). Specifically, the relative influence of stochastic processes on rare taxa and deterministic processes on abundant taxa increased with increasing aridity under lower aridity stress.…”

Foliar Herbivory Reduces Rhizosphere Fungal Diversity and Destabilizes the Co-occurrence Network

“…Microbial community stability is crucial to ensure ecosystem functioning ( Wu et al, 2021 ). Our study found that aboveground herbivores were quite capable of disturbing rhizofungal community stability.…”

“…Mounting evidence has revealed that species interactions in biological community networks are crucial for their stability ( Neutel et al, 2002 ; Coux et al, 2016 ). Likewise, the capacity of soil microbial communities to maintaining stability under disturbances largely depends on the complexity of interactions between species within that community ( Steele et al, 2011 ; Schmitt et al, 2012 ; Wu et al, 2021 ). Recently, co-occurrence network approaches have been increasingly applied to investigate in detail the association relationships among microbial individuals ( Faust et al, 2012 ; Ma et al, 2018b ; Shi et al, 2020a ; Yuan et al, 2021a ).…”

“…Recently, co-occurrence network approaches have been increasingly applied to investigate in detail the association relationships among microbial individuals ( Faust et al, 2012 ; Ma et al, 2018b ; Shi et al, 2020a ; Yuan et al, 2021a ). In addition, network robustness, calculated as the degree of natural connectivity determined by “attacking” the edges and nodes characterizing the network (removing the nodes and edges in the network randomly; Albert et al, 2000 ; Peng and Wu, 2016 ) is frequently being used ( Fan et al, 2018 ; Shi et al, 2019b ; Wu et al, 2021 ); higher robustness of networks (greater resistance of natural connectivity under attack) indicates that the community is more stable, while a sharply declining slope indicates lower network stability. It is conceivable that rhizofungal community networks may be sensitive to aboveground insect herbivory, as a form of biotic disturbance; nevertheless, their property changes and stability in response to insect herbivory remain largely unknown.…”