Increased Soil Carbon and Nitrogen Stocks Associate With Stronger Calcium-Microbial and Multi-Trophic Interactions...

Area of Science:

• Soil Science
• Ecology
• Biogeochemistry

Background:

• Converting cropland to planted forests can improve soil organic carbon (SOC) and total nitrogen (TN) storage, contributing to climate change mitigation.
• Mechanisms linking soil calcium (Ca), micro-food web interactions, and nutrient accumulation under warming are not fully understood.
• Understanding these pathways is crucial for optimizing land management for carbon sequestration.

Purpose of the Study:

• To investigate the roles of exchangeable Ca²⁺, soil micro-food web interactions, and nutrient accumulation in driving mineral-associated organic matter (MAOM), SOC, and TN accumulation in planted forests versus croplands under warming.
• To elucidate the mechanistic links between these factors and their contribution to soil carbon and nitrogen storage.

Main Methods:

• Compared MAOM, SOC, and TN content in planted forests and croplands under ambient and warming conditions.
• Assessed soil exchangeable Ca²⁺, microbial necromass, and Ca-microbial and multi-trophic associations.
• Utilized correlation analyses to determine relationships between soil properties, microbial interactions, and nutrient accumulation.

Main Results:

• Planted forests showed higher MAOM, SOC, and TN than croplands, with stronger carbon-nitrogen coupling.
• Warming increased MAOM, SOC, and TN in planted forests but decreased SOC in croplands.
• Planted forests exhibited elevated exchangeable Ca²⁺, microbial necromass, and stronger Ca-microbial and cross-trophic associations, which were amplified by warming and positively correlated with nutrient accumulation.

Conclusions:

• Warming promotes SOC and TN storage in planted forests by strengthening exchangeable Ca²⁺, Ca-microbial, and cross-trophic interactions.
• Cross-trophic associations, modulated by soil exchangeable Ca²⁺, are key drivers of MAOM, SOC, and TN accumulation in planted forests.
• Multi-trophic interactions and Ca-mediated processes are vital for stabilizing microbial necromass and enhancing carbon and nitrogen preservation during vegetation restoration under warming.