Whole-soil warming decreases abundance and modifies the community structure of microorganisms in the subsoil but not in surface soil

Abstract

Abstract. The microbial community composition in subsoils remains understudied, and it is largely unknown whether subsoil microorganisms show a similar response to global warming as microorganisms at the soil surface do. Since microorganisms are the key drivers of soil organic carbon decomposition, this knowledge gap causes uncertainty in the predictions of future carbon cycling in the subsoil carbon pool (> 50 % of the soil organic carbon stocks are below 30 cm soil depth). In the Blodgett Forest field warming experiment (California, USA) we investigated how +4 ∘C warming in the whole-soil profile to 100 cm soil depth for 4.5 years has affected the abundance and community structure of microorganisms. We used proxies for bulk microbial biomass carbon (MBC) and functional microbial groups based on lipid biomarkers, such as phospholipid fatty acids (PLFAs) and branched glycerol dialkyl glycerol tetraethers (brGDGTs). With depth, the microbial biomass decreased and the community composition changed. Our results show that the concentration of PLFAs decreased with warming in the subsoil (below 30 cm) by 28 % but was not affected in the topsoil. Phospholipid fatty acid concentrations changed in concert with soil organic carbon. The microbial community response to warming was depth dependent. The relative abundance of Actinobacteria increased in warmed subsoil, and Gram+ bacteria in subsoils adapted their cell membrane structure to warming-induced stress, as indicated by the ratio of anteiso to iso branched PLFAs. Our results show for the first time that subsoil microorganisms can be more affected by warming compared to topsoil microorganisms. These microbial responses could be explained by the observed decrease in subsoil organic carbon concentrations in the warmed plots. A decrease in microbial abundance in warmed subsoils might reduce the magnitude of the respiration response over time. The shift in the subsoil microbial community towards more Actinobacteria might disproportionately enhance the degradation of previously stable subsoil carbon, as this group is able to metabolize complex carbon sources.

Effects of pesticide treatment against nematode disease on soil bacterial community structure and sweet potato yield and quality

“…A total of 37 bacterial phyla were annotated from all soil samples, among which 10 were dominant (average relative content >1.00%). They were Actinobacteria (29.40%), Proteobacteria (28.13%), Acidobacteria (16.90%), Chloroflexi (9.97%), Gemmatimonadetes (2.70%), Firmicutes (2.30%), WPS‐2 (Candidatus Eremiobacterota) (1.99%), Bacteroidetes (1.81%), TM7 (Saccharibacterium) (1.62%) (Zosso et al., 2021), and Planctomycetes (1.47%), and the cumulative average relative content was up to 96.29%. Significant analysis of variance showed that the relative contents of 10 dominant phyla in soil bacterial communities after different pesticide treatments were not significantly different ( p > 0.05).…”

“…As an important part of the soil ecosystem, soil microorganisms could decompose organic matter in the soil, release growth hormones and trace elements, which are absorbed and utilized by plants, and improve the soil utilization rate (Vidal et al., 2021). Soil microorganisms play an important fundamental role in soil functions, and the community structure of soil microorganisms is a key factor regulating ecological functions (Wang, Liu, et al., 2020; Wang, She, et al., 2020; Zosso et al., 2021). The application of pesticides has toxic effects on soil microorganisms and soil animals, reduces the diversity of soil microorganisms (Li et al., 2020; Sim et al., 2022), destroys the ecological balance of soil, causes the loss of soil nutrients, and interferes with the material cycle and energy flow in soil (Tripathi & Gaur, 2021).…”

Climate Effects on Subsoil Carbon Loss Mediated by Soil Chemistry

“…As such, these insights support the need for future in situ studies of climate change effects on subsoil C flux that account for gradients in the dominant drivers of mineral SOC protection, in addition to ecological and physiological adaptations that may mitigate temperature or moisture response at longer timescales (e.g., shifts in vegetation, the soil microbiome, or soil chemical properties and mineralogy). 10,31,74,75 The potential for high warming response of soil respiration in tropical soils 33 also motivates the evaluation of system-dependent climate sensitivities, accounting for local soil chemical properties. Global subsoil measurements of both extractable base cations and reactive metals are imperative to the application of a framework for prediction of climate change response informed by the soil physicochemical gradient described here.…”

Effects of coffee pericarp and litter mulsching on soil microbiomes diversity and functions in a tropical coffee plantation, South China

“…There is a significant coupling relationship between soil microbiome structure assembly and diversity ( Zosso et al, 2021 ). The change in cultivation patterns can significantly change the structure of the soil microbiome through four regulatory pathways in the ecological recycling cultivation system ( Gao et al, 2022 ; Wang Y. et al, 2022 ; Zhang M. et al, 2023 ).…”