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

Micheal A. Davis, University of Southern Mississippi
SG Pritchard
RJ Mitchell
SA Prior

Abstract

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.