Tree Diversity Enhances Nitrogen Retention and Accelerates Phosphorus Cycling

Area of Science:

• Ecology
• Biogeochemistry
• Forest Science

Background:

• Nitrogen (N) and phosphorus (P) cycling are vital for ecosystem productivity and carbon sequestration.
• The precise mechanisms linking biodiversity to soil nutrient cycling remain incompletely understood, hindering accurate ecosystem modeling.
• Subtropical China presents a unique N-sufficient yet P-limited environment for studying nutrient dynamics.

Purpose of the Study:

• To investigate how tree species richness influences ecosystem nutrient cycling in a P-limited subtropical region.
• To elucidate the mechanistic links between tree diversity and N and P cycle regulation.

Main Methods:

• Conducted a large-scale tree diversity experiment in subtropical China.
• Analyzed changes in N and P stocks, plant nutrient resorption, soil nutrient availability, and microbial activity.
• Measured N leaching, N2O emissions, and stable isotopes (δ15N) to assess N cycling efficiency.

Main Results:

• Increased tree species richness led to enhanced N retention through boosted plant N uptake and recycling, reduced N leaching, and lower N2O emissions.
• Evidence of tighter N cycling was observed, indicated by reduced soil δ15N values.
• Tree diversity elevated soil acid phosphatase activity, increased foliar P resorption efficiency, and enhanced plant P storage, accelerating P cycling.

Conclusions:

• Tree species richness directly regulates both nitrogen and phosphorus cycling in terrestrial ecosystems.
• Biodiversity plays a critical role in mitigating nutrient imbalances and enhancing ecosystem resilience to nutrient limitations.
• Findings provide experimental evidence crucial for modeling ecosystem responses to biodiversity changes.