High Microbial Diversity Promotes Soil Ecosystem Functioning.

Area of Science:

• Soil Ecology
• Microbial Ecology
• Biogeochemistry

Background:

• Functional redundancy in soil microbial communities challenges the direct link between microbial diversity and carbon transformations.
• The relationship between microbial diversity and soil carbon cycling is not fully understood, particularly concerning different carbon source types.

Purpose of the Study:

• To investigate how decreasing microbial diversity affects the decomposition of easily degradable (allochthonous) versus recalcitrant (autochthonous) carbon sources.
• To test the hypothesis that functional redundancy decreases with increasing carbon source recalcitrance, altering the diversity-carbon cycling relationship.

Main Methods:

• Manipulated microbial diversity in controlled laboratory experiments.
• Assessed the decomposition rates of allochthonous and autochthonous carbon sources under varying diversity levels.
• Measured global carbon dioxide (CO2) emissions as an indicator of decomposition.

Main Results:

• A decrease in microbial diversity significantly affected the decomposition of both autochthonous and allochthonous carbon sources.
• Reduced microbial diversity led to a decrease in overall CO2 emissions by up to 40%.
• Lower diversity shifted CO2 emissions towards the preferential decomposition of more degradable carbon sources, with effects amplified by nutrient availability.

Conclusions:

• Soil carbon cycling is more sensitive to microbial diversity changes than previously thought, especially in nutrient-rich environments.
• Preserving soil microbial diversity is crucial for maintaining soil ecosystem services, including carbon storage, particularly under global change scenarios.
• Findings underscore the importance of microbial diversity for organic matter decomposition and soil carbon dynamics.