Elevated atmospheric CO2 affects structure of a model regenerating longleaf pine community

Differences in plant morphology, physiology, life form, and symbiotic relationships can generate differences in species responses to CO2-enrichment, which call alter competitive interactions, thus affecting community structure and function. Here, we present data from a two-year study, examining the species and community responses to elevated[CO2] of a model regenerating longleaf pine community. The model community was constructed from an assemblage of early successional forest species representing major functional guilds within a typical longleaf pine-wiregrass community: (1) a C-3 evergreen conifer (Pinus palustris); (2) a C-4 bunch grass (Aristida stricta); (3) a C-3 broadleaf tree (Quercus margaretta); (4) a C-3 perennial herbaceous legume (Crotalaria rotundifolia); and (5) a C-3 herbaceous perennial (Asclepias tuberosa). After 2 years, CO2-enriched plots had 109% greater above-ground biomass than ambient plots, mainly due to a 117%, increase in pine biomass. Community structure was altered by CO2 enrichment; Crotalaria and Asclepias 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 altered competitive interactions for light and soil moisture.