Soil Microbes Mediate Productivity Differences Between Natural and Plantation Forests.

Area of Science:

• Ecology
• Soil Science
• Forestry

Background:

• Forest productivity is influenced by climate, but the role of soil microbial communities, especially the differences between natural and plantation forests, is not well understood at large scales.
• Quantifying the mechanistic contribution of soil microbes to forest productivity divergence is crucial for understanding ecosystem function.

Purpose of the Study:

• To conduct a unified analysis evaluating climate, soil conditions, and soil microbes to compare the mechanisms behind productivity differences in natural versus plantation forests.
• To assess how microbial diversity, dominant taxa, and soil drivers relate to forest productivity (gross primary productivity and net primary productivity) across forest types.

Main Methods:

• Synthesized data from 237 observations across China, integrating productivity metrics with microbial and soil data.
• Employed structural equation models to identify key drivers of productivity and random forest models to pinpoint predictors of microbial diversity.

Main Results:

• Plantation forest productivity exhibited nonlinear responses to microbial diversity and was more sensitive than natural forests.
• Natural forests had higher bacterial diversity (Shannon, Chao1) and distinct microbial taxa (e.g., *Nitrobacter*, *Bradyrhizobium*, *Cortinarius*).
• Plantations were characterized by opportunistic taxa (e.g., *Sphingomonas*, *Fusarium*, *Gemmatimonas*), suggesting functional simplification. Climate was the strongest productivity correlate, while soil properties like cation-exchange capacity and total nitrogen were key predictors of microbial diversity in plantations.

Conclusions:

• Soil microbial communities are differentially associated with forest productivity across forest types and environmental contexts.
• Understanding these differences is vital for effective forest management and conservation strategies.
• Future research should incorporate climate-comparable designs and management intensity data to better isolate microbial contributions to forest productivity.