Localized plant-soil-microbe interactions regulate spatial variations of soil oxidase activities within afforested systems in a subtropical area

Soil oxidases play a vital role in soil organic carbon decomposition. However, the question how biotic and abiotic factors interactively affect spatial variations of soil oxidase activities within ecosystems remains unresolved. Here, we identified soil oxidase (peroxidase (PER) and polyphenol oxidase (PPO)) activities at different locations within two afforested systems (coniferous woodland and leguminous shrubland), and investigated the associated variables of vegetation, soil environments, microbial communities and spatial structure to explore their relative importance in regulating oxidase activities. Our results showed that 32.5%–46.9% of variations in oxidase activities could be explained by the localized effects of vegetation, soil environments and microbial communities. Plant-soil-microbe interactions explained more variations of oxidases compared to the sole fraction of each group. High oxidase activities were closely associated with high pH and low present litter biomass. Meanwhile, the abundance of gram-negative bacteria was the key microbial factor on oxidase activities in the woodland, while the abundance of gram-positive bacteria was the key factor on PER activity in the shrubland. Taken together, our results provide novel experimental insight into spatial variability of soil oxidases, and reveal a profound impact of key vegetation, soil and microbial factors and their localized interactions on spatial patterns of soil oxidases at ecosystem-level.