Restoration of grassland biodiversity and soil carbon sequestration: Synergistic goal?

Conservation of biodiversity and carbon sequestration are both of major concern in a world facing global change. Diverse plant communities can enhance carbon fixation by increased primary productivity above-ground. However, the effect of plant diversity on carbon sequestration and carbon loss below-ground remains largely unexplored. Here we investigate whether management practices aimed at restoration of grassland diversity also impact on soil carbon sequestration. We hypothesized that restoration practices, such as reduced fertilizer application and seeding treatments, stimulate carbon sequestration by promoting above-ground plant as well as soil carbon pools. We investigated the above-ground and below-ground carbon pools in a mesotrophic grassland in northern England, subjected to 15 years of restoration. Preliminary results indicate that on a per area basis the soil carbon pool outweighs above-ground carbon pools, and mainly comprises old carbon. Cessation of fertilizer application has increased the total soil carbon pool, especially in the young soil carbon pool. The total above-ground carbon pool was not affected by restoration practices. However, cessation of fertilizer application reduced the total carbon pool in plant shoots and roots, and enhanced it in bryophytes. Interactions between seed additions and fertilizer application were found for the pool of carbon in roots. Further investigations will link the changes in vegetation and soil microbial communities to the restoration-induced changes in soil carbon sequestration.