Interconnections among co-existing soil bacteria taxa drive the home-field advantage of litter decomposition

Abstract

The home-field advantage (HFA) hypothesis postulates that plant litter decomposes faster in the home habitat than in other locations (i.e., away site) due to specialized microbial decomposers. However, we still have limited understanding of how specific microbes contribute to HFA. Here, we examined how variation in HFA relates to differences in soil bacterial diversity and interconnections among co-existing bacteria taxa. A 480-d reciprocal transplant experiment was designed using Schima superba and Zea mays litter collected from forest and farmland ecosystems, respectively. Our findings showed that litter decomposition is associated with specific soil bacterial taxa that generate HFA effects for litter use. The decomposition of labile Z. mays litter in away site increased the biodiversity of soil bacteria, thereby creating more complex and stable co-occurrence networks. In contrast, the decomposition of recalcitrant S. superba litter in away site reduced the interconnections among co-existing taxa by preventing the establishment of specific taxa such as Proteobacteria and Actinobacteria, resulting in less complex and stable networks. The simplified bacterial networks in away sites led to reduced ecosystem functions, including nutrient cycling and decomposition, and were responsible for the generation of HFA in litter decomposition. Furthermore, the effect of soil bacterial diversity on litter mass loss was indirectly driven by network stability, suggesting that interconnections among co-existing taxa enable a better explanation how specific microbes contribute to drive HFA than the diversity metrics. Our results highlight the importance of co-occurrence networks as a key component of microbial biodiversity linking it with litter decomposition.