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Title: GLOBAL CLIMATE CHANGE AND COMMUNITY STRUCTURE: EFFECTS OF ELEVATED ATMOSPHERIC CO2 ON COMPETITION IN A MODEL LONGLEAF PINE COMMUNITY

Author
item DAVIS, MICHEAL - AUBURN UNIVERSITY
item Pritchard, Seth
item MITCHELL, ROBERT - JONES ECOLOGICAL RES CTR
item Prior, Stephen - Steve
item Rogers Jr, Hugo
item Runion, George

Submitted to: Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/19/2001
Publication Date: 2/26/2002
Citation: Davis, M.A., Pritchard, S.G., Mitchell, R.J., Prior, S.A., Rogers, H.H., and Runion, G.B. 2002. Global climate change and community structure: Effects of elevated atmospheric CO2 on competition in a model longleaf pine community. Journal of Ecology 90:130-140.

Interpretive Summary: Longleaf pine lands in the Southeast have been reduced by >95% since the 1600s. This drastic reduction makes these systems sensitive to further stresses, such as the altering of the global carbon cycle through increased atmospheric CO2. As atmospheric CO2 continues to rise, it is important to understand plant responses to CO2 enrichment. Different types of plants have differing responses to elevated CO2 which could change competition between plants. We constructed a pine community and exposed it to ambient or twice-ambient levels of atmospheric CO2. We used five kinds of plants: longleaf pine, sand post oak, wiregrass, rattlebox, and butterfly weed. These species differ in both form and function. After two years, plots exposed to high CO2 had over twice the weight, mostly due to increased pine growth. Butterfly weed and rattlebox performed poorly under high CO2. Our data suggest that longleaf pine communities as a whole will perform well in a future higher CO2 world, but some plants may fall prey to competition.

Technical Abstract: The land area occupied by longleaf pine forests in the southeastern United States has been reduced by >95% since the 1600s. Consequently, these ecosystems are sensitive to further anthropogenic influences, such as the altering of the global carbon cycle via increased atmospheric CO2 emissions. As atmospheric CO2 continues to rise (it is predicted to double in the next century), it is critical to further our understanding o plant community responses to CO2 enrichment. Differences in morphology, physiology, life form, and symbiotic relationships generate differences in species responses to CO2 enrichment, which can alter competitive interactions, thus affecting community structure and function. Here, we present data from a two-year study, examining the community responses to elevated CO2 of a model regenerating longleaf pine community. The model was constructed from an assemblage of early successional forest species representing major functional guilds within a typical longleaf pine- wiregrass community: (1) a C3 evergreen conifer; (2) a C4 bunch grass; (3) a C3 broadleaf tree; (4) a C3 perennial herbaceous legume; (5) a C3 herbaceous prennial. After two years, CO2-enriched plots had 109% greater aboveground biomass than ambient plots, mainly due to a 117% increase in pine biomass. Overall community structure was largely unaffected by CO2 enrichment. Some species had higher mortality and less biomass in high CO2 plots, suggesting that not all species will perform well as global CO2 rises. Our data suggest that longleaf pine communities as a whole will perform well in a future higher CO2 world, but some species may fall prey to competitive interactions for light and soil moisture.