Soil microbial functioning and organic carbon storage: can complex timber tree stands mimic natural forests?

Area of Science:

• Soil Science
• Ecology
• Forestry

Background:

• Conversion of natural forests to anthropogenic land use systems (LUS) can lead to significant carbon loss.
• Proper management of LUS may offer potential for carbon sequestration and improved soil health.
• Understanding soil microbial functioning and soil organic carbon (SOC) dynamics is crucial for sustainable land management.

Purpose of the Study:

• To assess soil microbial functioning and SOC stocks in different tree stands in Côte d'Ivoire's semi-deciduous forest zone.
• To determine if complex tree stands can replicate the soil attributes of natural forests.
• To evaluate the potential of mixed tree stands (MTS) as a climate-smart forestry approach.

Main Methods:

• Compared soil properties (0-10 cm depth) in natural forest, teak monoculture, cocoa monoculture, and a mixed tree stand (MTS).
• Analyzed soil organic carbon (SOC) stocks, microbial biomass carbon (MBC), microbial activities, MBC/SOC ratio, and metabolic quotient (qCO2).
• Calculated carbon mineralization rates and mineral nitrogen concentrations across different land use systems.

Main Results:

• Monocultures of cocoa and teak showed significantly lower C mineralization and mineral N concentrations compared to natural forest.
• SOC stocks were significantly reduced in teak and cocoa monocultures but comparable in MTS to the natural forest.
• MTS exhibited soil microbial functioning (MBC/SOC ratio, qCO2) similar to the natural forest, suggesting enhanced soil health.

Conclusions:

• Complex mixed tree stands (MTS) can effectively mimic natural forests in maintaining soil microbial activity and organic carbon status.
• The diversity of litter quality in MTS contributes to their ability to sustain soil health.
• Mixed tree stands present a viable strategy for developing climate-smart timber systems in West and Central Africa.