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Title: NITROGEN AND CARBON CYCLING IN A MODEL LONGLEAF PINE COMMUNITY AS AFFECTED BY ELEVATED ATMOSPHERIC CO2

Author
item Torbert, Henry - Allen
item Prior, Stephen - Steve
item Runion, George
item DAVIS, MICHEAL - UNIV. OF SO. MISS.
item PRITCHARD, SETH - BELMONT UNIVERSITY
item Rogers Jr, Hugo

Submitted to: Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/18/2003
Publication Date: 7/15/2004
Citation: Torbert III, H.A., Prior, S.A., Runion, G.B., Davis, M.A., Pritchard, S.G., Rogers Jr, H.H. 2004. Nitrogen and carbon cycling in a model longleaf pine community as affected by elevated atmospheric co2. Environmental Management. 33(1):S132-s138

Interpretive Summary: Increasing atmospheric CO2 concentration has led to concerns regarding its potential effects on environment, including the potential for global warming. It has been theorized that some of the atmospheric C can be stored in the soil and trees in forest. This study examined the potential of storing C in the soil of a longleaf pine forest when growing under elevated CO2 conditions. The study consisted of a model of a typical longleaf pine-wiregrass community consisting of the following plants: longleaf pine; wiregrass; sand post oak; rattlebox; and butterfly weed. These species (common associates throughout the southeastern U.S.) were grown at normal and twice normal CO2 concentrations. The CO2-enriched plots had greater aboveground biomass growth, mainly due to increased pine biomass. Soil samples indicated a decreased soil C respiration and C turnover, but increased N mineralization with the elevated CO2. The results indicate that an increase in soil C storage is likely for soils in this longleaf pine ecosystem under elevated CO2 conditions.

Technical Abstract: Increasing global atmospheric CO2 concentration has led to concerns regarding its potential effects on the terrestrial environment and the long-term storage of C and N in soil. A study examined the responses to elevated CO2 of a typical regenerating longleaf pine-wiregrass community. The study consisted of a model community of five plant species: 1) an evergreen conifer (Pinus palustris), 2) a bunch grass (Aristida stricta), 3) a broadleaf tree (Quercus margaretta), 4) a perennial herbaceous legume (Crotalaria rotundifolia), and 5) a herbaceous perennial (Asclepias tuberosa) grown at two CO2 concentrations (ambient and twice ambient). The CO2-enriched plots had greater aboveground biomass than ambient plots, mainly due to increased pine biomass. After 3 yrs, soil (Blanton loamy sand: loamy, siliceous, thermic Grossarenic Paleudult) samples were collected from 0-5, 5-10, and 10-20 cm depth increments. Microbial respiration, potential C and N mineralization, and C turnover were measured during a 120 d incubation of the soil samples. Elevated CO2 decreased soil C respiration and C turnover, but increased N mineralization. The results indicate that soil C sequestration is likely for soils in this longleaf pine ecosystem.