HR: 1340h
AN: B43B-1173    [Abstracts]
TI: Effects of invasive species on ecosystem carbon dynamics in a restored tallgrass prairie
AU: * Matamala, R
EM: matamala@anl.gov
AF: Argonne National Laboratory, sion, BioSciences Division, Argonne, IL 60439, United States
AU: Graham, S L
EM: sgraha3@uic.edu
AF: University of Illinois at Chicago, Department of Biological Sciences, Chicago, IL 60607, United States
AU: Cook, D R
EM: drcook@anl.gov
AF: Argonne National Laboratory, Environmental Sciences Division, Argonne, IL 60439, United States
AU: Gonzalez-Meler, M A
EM: mmeler@uic.edu
AF: University of Illinois at Chicago, Department of Biological Sciences, Chicago, IL 60607, United States
AB: Land cover is an important determinant of soil C storage and dynamics. Restoration of degraded ecosystems and soils represents a target sink for offsetting rising atmospheric CO₂ levels by increasing carbon sequestration in soils. The Conservation Reserve Program (CRP) and other initiatives to halt land degradation after cessation of cultivation present opportunities to assess the C sequestration potential of restoration practices. Our aim is to study what key ecosystem and climatic components exert the largest leverage for these lands to be sustainable C sinks. When considering controls on ecosystem C cycling, biodiversity has the potential to be a strong biotic influence. Invasive species can disrupt ecosystem processes by exhibiting functional characteristics which are distinct from their native counterparts. Invasive species, while affecting nearly all ecosystems, may pose a particular threat to restorations and impact rates of C accrual. We measured net ecosystem production (NEP) at a 18 years-old restored tallgrass prairie using the eddy covariance technique coupled to biometric estimates of biomass and soil C in a two year study where climatic conditions and plant species dominance varied. In 2005, the prairie restoration was a strong C sink with a NEP 438 gCm^-2, despite a pronounced spring drought. In 2006, with above normal precipitation, a Melilotus alba dominance dramatically reduced NEP when compared to 2005. The loss of ecosystem functional diversity that resulted from the dominance of the invasive M. alba led to a 42% reduction in the length of the photosynthetically active season, as compared to the previous year. These results suggest that understudied biotic limitations to NEP may outweigh the effects of more commonly studied abiotic limitations. Ecosystem models and management strategies should consider biotic limitations to NEP in grasslands in order to maximize long term C sequestration of restorations and CRP management practices.
DE: 0410 Biodiversity
DE: 0428 Carbon cycling (4806)
DE: 0476 Plant ecology (1851)
DE: 0481 Restoration
SC: Biogeosciences [B]
MN: 2007 Fall Meeting