February 3rd, 2010
In another example of an exotic grass altering carbon storage, Japanese stiltgrass (Microstegium vimineum), which is invading many US forests, has been found to reduce soil carbon stores, probably by stimulating higher rates of decomposition in the soil.
According to Michael Strickland and fellow researchers, extra losses of native plant-derived carbon due to more rapid decomposition are greater than carbon gains from the extra photosynthesis due to invasion.
They proposed that the invader increases soil carbon turnover through higher quality litter inputs and perhaps also through root exudates. Such exudates partly consist of glucose and other compounds that are readily used by soil microbes and have stimulated decomposition when applied to soils.
If their results apply to other sites of invasion by stiltgrass, they have long term implications for forest soil fertility and carbon storage.
Strickland MS, Devore JL, Maerz JC, Bradford MA. 2009. Grass invasion of a hardwood forest is associated with declines in belowground carbon pools. Global Change Biology (2009), doi: 10.1111/j.1365-2486.2009.02042.x.