Dispersal changes soil bacterial interactions with fungal wood decomposition

Abstract

Although microbes are the major agent of wood decomposition - a key component of the carbon cycle - the degree to which microbial community dynamics affect this process is unclear. One key knowledge gap is the extent to which stochastic variation in community assembly, e.g. due to historical contingency, can substantively affect decomposition rates. To close this knowledge gap, we manipulated the pool of microbes dispersing into laboratory microcosms using rainwater sampled across a transition zone between two vegetation types with distinct microbial communities. Because the laboratory microcosms were initially identical this allowed us to isolate the effect of changing microbial dispersal directly on community structure, biogeochemical cycles and wood decomposition. Dispersal significantly affected soil fungal and bacterial community composition and diversity, resulting in distinct patterns of soil nitrogen reduction and wood mass loss. Correlation analysis showed that the relationship among soil fungal and bacterial community, soil nitrogen reduction and wood mass loss were tightly connected. These results give empirical support to the notion that dispersal can structure the soil microbial community and through it ecosystem functions. Future biogeochemical models including the links between soil microbial community and wood decomposition may improve their precision in predicting wood decomposition.

Not all soil carbon is created equal: Labile and stable pools under nitrogen input

“…Heat tree analysis indicated that N input increases the abundance of Proteobacteria , Firmicutes , and Bacteroidetes and slightly increases the abundance of Acidobacteria and Verrucomicrobia (at medium and high N levels). Fungi are considered to have more oligotrophic characteristics than bacteria (Wang & Kuzyakov, 2024), often are less sensitive, and have inconsistent responses to long‐term nutrient addition (de Vries et al., 2018; Jansson & Hofmockel, 2022). The relative abundances of hemicellulose, cellulose, and chitin degradation genes were observed under N input in the long term (Figure 5), suggesting that N decreased the production of C‐degrading enzymes by soil bacteria and further suppressed SOM mineralization.…”

“…N input shifts microbial communities by giving an advantage to copiotrophs over oligotrophs, which utilize labile and stable compounds, respectively (Dai et al., 2018; Ramirez et al., 2012). Bacteria and fungi degrade labile and stable substances by producing hydrolytic and oxidative enzymes (Cusack et al., 2011; Jian et al., 2016), whereas bacteria are more efficient in the utilization of labile, and fungi for persistent compounds (Wang & Kuzyakov, 2024). N input can decrease microbial N mining from SOM and increase microbial C use efficiency, without affecting total microbial biomass (Spohn et al., 2016; Zang, Blagodatskaya, Wang, et al., 2017).…”