Impacts of forest thinning on soil microbial community structure and extracellular enzyme activities: A global meta-analysis
Tao Zhoua,b, Chuankuan Wanga,b, Zhenghu Zhoua,b
Center for Ecological Research, Northeast Forestry University, 26 Hexing Road, Harbin, 150040, China.
Thinning profoundly affects soil microbial communities and carbon (C) cycling through altering soil microclimate, plant growth, C inputs and allocations. However, these effects are uncertain and may change with thinning intensity, recovery stage, forest type, and climate. Here, we conducted a global meta-analysis, based on 337 observations from 49 studies, to quantify the responses of soil properties, microbial biomass and community structure, and extracellular enzyme activities (EEAs) to thinning. We found that thinning did not change the total microbial biomass, but significantly shifted the soil microbial community structure and EEAs. Thinning stimulated both C-oxidase and C-hydrolase, but decreased the ratio of oligotrophic to copiotrophic microbes (i.e. fungi to bacteria ratio and Gram-positive bacteria to Gram-negative bacteria ratio) in the early recovery stage. In contrast, in the mid recovery stage, thinning enhanced C-oxidase but reduced C-hydrolase, and increased the ratio of oligotrophic to copiotrophic microbes. In the late recovery stage, neither community structure nor EEAs differed significantly between thinned and control stands. Such recovery dynamics reflect shifts of the resource-utilization strategies of microbes that are associated with community reorganization. Besides, the distinct litter quality between coniferous and broadleaf forests explained their different microbial responses. Overall, the current meta-analysis suggested that microbes can adapt the thinning-induced biotic and abiotic changes by adjustment of community structure rather than their biomass. The global patterns of how soil microbial community structure and EEAs respond to thinning deepen the understanding of the mechanisms underlying the thinning impacts on the soil C cycling.
Keywords: Forest thinning, Extracellular enzymes, Microbial community, Forest management, Fungi:bacteria.