We repeatedly sampled the surface mineral soil (0–20 cm depth) in three northern temperate forest communities over an 11-year experimental fumigation to understand the effects of elevated carbon dioxide (CO 2 ) and/or elevated phyto-toxic ozone (O 3 ) on soil carbon (C). After 11 years, there was no significant main effect of CO 2 or O 3 on soil C. However, within the community containing only aspen ( Populus tremuloides Michx.), elevated CO 2 caused a significant decrease in soil C content. Together with the observations of increased litter inputs, this result strongly suggests accelerated decomposition under elevated CO 2. In addition, an initial reduction in the formation of new (fumigation-derived) soil C by O 3 under elevated CO 2 proved to be only a temporary effect, mirroring trends in fine root biomass. Our results contradict predictions of increased soil C under elevated CO 2 and decreased soil C under elevated O 3 and should be considered in models simulating the effects of Earth’s altered atmosphere.
Peer Reviewed
http://deepblue.lib.umich.edu/bitstream/2027.42/78639/1/j.1461-0248.2009.01380.x.pdf