Plant functional composition influences rates of soil carbon and nitrogen accumulation

Summary

This 12-year field experiment at Cedar Creek, Minnesota demonstrates that high-diversity grassland plant mixtures accumulated substantially more soil carbon and nitrogen than monocultures on degraded soils. The effect was driven by functional complementarity between legume species (providing biological nitrogen fixation) and C4 grasses (efficient nitrogen uptake and below-ground biomass allocation). The findings suggest that specific plant functional group combinations—particularly C4 grass–legume associations—are key drivers of soil carbon accumulation and ecosystem services in diverse grassland systems.

Regional applicability

This study was conducted in the United States (Minnesota), but the mechanisms identified—functional complementarity between nitrogen-fixing legumes and efficient C4 grasses—are relevant to United Kingdom grassland management and soil restoration. However, UK grassland systems differ in climate, existing species pools, and historical management, so direct transference of species combinations would require adaptation to temperate conditions and native/naturalised species.

Key measures

Net soil carbon accumulation (to 1 m depth), net soil nitrogen accumulation (to 1 m depth), root biomass, root biomass distribution to 60 cm soil depth

Outcomes reported

The study measured net soil carbon and nitrogen accumulation to 1 metre depth over 12 years in a grassland biodiversity experiment, quantifying the effects of plant functional composition on soil C and N storage rates.

Topic tags