Exploring the Control of Plant Diversity On Microbial Residue Storage in Experimental Grasslands.

Rising atmospheric CO₂ concentration and global mean temperatures, as a threatening trend, has stimulated interest in the potential for terrestrial systems to sequester carbon and mitigate climate change. In “WICST Prairie Establishment Experiment”, a managed grassland experiment on a former agricultural field, we investigated the control of plant diversity on microbial residue and carbon storage with soil depth. The two prairie treatments established since 1999 were a high diversity prairie (hdpR, 25 species) and a low diversity prairie (ldpR, 6 species). Stratified soil samples were taken in 2008 through 100-cm depth with 5 intervals: 0-2 cm, 12-15 cm, 25-27 cm, 50-52 cm and 98-100 cm. We found that the microbial residue amino sugars appeared to decrease downward through the profile in all treatments. Following a decade of management, the ldpR treatment in top layer significantly accumulates more microbial residues than the ldpR treatment, while amino sugars tend to be more enriched in bottom layer for the hdpR treatment. Our analysis indicates that plant species richness accelerate the build-up of new carbon pools. Additionally, high plant diversity mitigated soil microbial residue losses in deeper horizons, while low plant diversity functioned in top horizons. This suggests that higher plant diversity might sustain higher soil carbon sequestration by recalcitrant inputs in the long-term and, therefore diversity conservation might play a role in greenhouse gas mitigation.