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Title: SENSITIVITY OF PROSOPIS VELUTINA TO SUMMER RAINFALL AND CONSEQUENCES FOR SEASONAL PATTERNS OF ECOSYSTEM CARBON EXCHANGE 1793

Author
item POTTS, D. - UNIVERSITY OF ARIZONA
item CABLE, J. - UNIVERSITY OF ARIZONA
item Scott, Russell - Russ
item WILLIAMS, D. - UNIVERSITY OF WYOMING
item Goodrich, David - Dave
item HUXMAN, T. - UNIVERSITY OF ARIZONA

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 10/1/2005
Publication Date: 12/5/2005
Citation: Potts, D.L., Cable, J.M., Scott, R.L., Williams, D.G., Goodrich, D.C., Huxman, T.E. 2005. Sensitivity of prosopis velutina to summer rainfall and consequences for seasonal patterns of ecosystem carbon exchange. {abstract}. Eos. Trans. AGU, 86(52), Fall Meet. Suppl. Abstract B43D-0302.

Interpretive Summary:

Technical Abstract: Future changes in dryland vegetation composition will interact with climate variability to influence carbon and water cycling in unforeseen ways. Observed increases in the density of woody plants in North America's savanna ecosystems may be an important terrestrial carbon sink and could alter patterns of regional hydrologic cycling. During the 2005 growing season we compared seasonal patterns of Prosopis velutina plant water status and leaf gas exchange in upland and riparian savannas. Previous work suggested the plant size class constrained alluvial groundwater access and that mature individuals were less sensitive to the onset of summer rains at the riparian site. We predicted that at the upland site, where groundwater was unavailable, mature and juvenile plants would respond similarly to the onset of summer rains. Furthermore, we predicted that this increased sensitivity by the dominant vegetation to seasonal rainfall would be reflected in NEE data collected by eddy-covariance at both sites. Results indicate that mesquite performance and the duration and magnitude of ecosystem carbon exchanges are tightly linked to precipitation at the upland site. Comparing upland and riparian sites demonstrates how seasonal pattern of precipitation, plant-available alluvial groundwater and vegetation structure interact to govern ecosystem carbon balance in savanna ecosystems.