More grass species, more carbon captured

Do you want the good news or the good news?

OK, researchers have discovered two things of vital importance to soil C sequestration:

1. rising temperatures from Global Warming will increase biodiversity in grasslands; and

2. increasing diversity in grasslands means more carbon is sequestered in the soil.

FINDING 1: le Roux and McGeoch (2008) have discovered "the expansion of species distributions along their cooler boundaries in response to rising temperatures," which "appears to be a consistent biological consequence of recent climate warming," and which we have further indicated leads to increases in local biodiversity throughout the world.*

FINDING 2: Another group of scientists in Jena, Germany, concluded "carbon storage significantly increased with sown species richness in all depth segments and even carbon losses were significantly smaller with higher species richness." Consequently, they concluded that "plant species richness ... accelerate[d] the build-up of new carbon pools within four years," and that "higher plant diversity mitigated soil carbon losses in deeper horizons."**

They had sowed 20m by 20m plots of soil with seeds of either 1, 2, 4, 8, 16 or 60 species of either 1, 2, 3 or 4 plant functional groups (grasses, small herbs, tall herbs, and legumes). During the first two years of the study, soil carbon storage was limited to the top five cm of soil, while below ten cm depth, carbon was actually lost. After four years, however, carbon stocks had increased significantly within the top twenty cm of the soil.

The journal's editor comments: "this phenomenon represents a previously unrecognized negative feedback phenomenon, since studies such as that of le Roux and McGeoch have demonstrated that global warming typically leads to higher local and regional biodiversity wherever the process has been studied throughout the world."

*Le Roux, P.C. and McGeoch, M.A. 2008. Rapid range expansion and community reorganization in response to warming. Global Change Biology 14: 2950-2962.
**Steinbeiss, S., Bessler, H., Engels, C., Temperton, V.M., Buchmann, N., Roscher, C., Kreutziger, Y., Baade, J., Habekost, M. and Gleixner, G. 2008. Plant diversity positively affects short-term soil carbon storage in experimental grasslands. Global Change Biology 14: 2937-2949