Optimizing soil carbon sequestration: The role of biopores in plant diversity and strategic species combinations

Plant diversity promotes soil organic carbon (SOC) gains through intricate changes in root-soil interactions and their subsequent influence on soil physical and biological processes. The goal of this study was to assess SOC and pore characteristics of soils under a range of switchgrass-based plant systems, representing a gradient of plant diversity with species richness ranging from 1 to 30. We focused on the structure of biopores, assumed to represent a legacy of root activities, and its relationships with SOC accumulation in the studied systems.

Our findings reveal that plant diversity enhances SOC through biopore-mediated mechanisms, with plant functional richness accounting for 29% of bioporosity variation and bioporosity explaining 32% of the variation in SOC. While a positive correlation between plant diversity and SOC accumulation was observed across all studied systems, a two-species mixture of switchgrass (Panicum virgatum L.) and ryegrass (Elymus canadensis) exhibited the highest bioporosity and achieved SOC levels comparable to those of the systems with 6 and 10 plant species, and inferior only to the system with 30 species. The findings suggest the potential for identifying specific plant combinations that efficiently foster biopore formation and promote SOC sequestration.