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Title: EFFECTS OF GLOBAL CHANGE ON SOUTHERN PINE FORESTS: RESPONSE OF A REGENERATING LONGLEAF PINE COMMUNITY TO ATMOSPHERIC CO2 ENRICHMENT

Author
item DAVIS, MICHEAL - UNIV. OF SO. MISS.
item Pritchard, Seth
item Rogers Jr, Hugo
item MITCHELL, ROBERT - JONES ECOL. RES. CTR.
item Runion, George
item Prior, Stephen - Steve
item GJERSTAD, DEAN - AUBURN UNIVERSITY
item DUTE, ROLAND - AUBURN UNIVERSITY

Submitted to: Environmental Protection Agency
Publication Type: Other
Publication Acceptance Date: 11/7/2002
Publication Date: 11/7/2002
Citation: Davis, M.A., Pritchard, S.G., Rogers, H.H., Mitchell, R.J., Runion ,G.B., Prior, S.A., Gjerstad, D.H., and Dute, R.R. 2002. Effects of Global Change on Southern Pine Forests: Response of a Regenerating Longleaf Pine Community to Atmospheric CO2 Enrichment. Final Technical Report, Experimental Program to Stimulate Competitive Research (Contract No. R826259-1), U.S. EPA, Washington, DC. 103 pp.

Interpretive Summary: Understanding the influence of the rise in global atmospheric CO2 on the structure and function of forest ecosystems is important due to their economic and ecological value. This is particularly true for Longleaf pine savannahs which once occupied 37.2 million ha of the southeastern United States; however, due to factors such as timber harvesting, fire suppression, and conversion of forests to farmland, the land area of this system now occupies less than 4% of its original range. A model regenerating Longleaf pine community consisting of an evergreen conifer (longleaf pine), a bunch grass (wiregrass), a broadleaf tree (sand post oak), a perennial herbaceous legume (rattlebox), and a herbaceous perennial (butterfly weed) was exposed to two levels of atmospheric CO2 (ambient or elevated). Productivity of longleaf pine forests will likely be enhanced by rising levels of atmospheric CO2, although community structure may be altered.

Technical Abstract: Barring further anthropogenic degradation of remaining habitats, Sandhills type longleaf forests should perform well in a future higher CO2 world. These data indicate that Pinus palustris and Aristida stricta would remain keystone species in future longleaf forests. Productivity of longleaf pine forests will likely be enhanced by rising levels of atmospheric CO2, although community structure may be altered. The ability of longleaf pine ecosystems to sequester carbon will likely increase as CO2 rises. Increases in allocation to woody biomass and increases in belowground allocation of C will enhance the C sequestration capabilities of these longleaf ecosystems. The pyric characteristics of this fire-dependent ecosystem should also be well-maintained. Caution should be used, however, when making broad ecosystem-scale predictions from this experiment. Small understory species did not perform well in CO2-enriched portions of our model ecosystem. If species diversity is reduced in these communities, then total ecosystems response to elevated CO2 may be reduced. Frequently burned Sandhills savannahs typically have > 40 species ha-1 that represent a variety of growth forms, hence it is impossible to make accurate predictions for each species. However, longleaf ecosystems harbor a large number of threatened and endangered species and their current tenuous position in these communities may become more imperiled if these species cannot maintain or improve their competitive abilities as atmospheric CO2 continues to rise.