ARS | Publication request: SOIL AND CANOPY CONTROL OVER ECOSYSTEM CARBON AND WATER FLUXES IN A DESERT GRASSLAND: PATTERNS FROM A RAINFALL MANIPULATION EXPERIMENT 1791

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: October 1, 2005
Publication Date: December 5, 2005
Citation: Huxman, T.E., Williams, D.G., Scott, R.L., Cable, J.M., Potts, D., Payao-Zuckerman, M., Ignace, D. 2005. Soil and canopy control over ecosystem carbon and water fluxes in a desert grassland: patterns from a rainfall manipulation experiment. {abstract}. Eos. Trans. AGU, 86(52), Fall Meet. Suppl. Abstract B41D-0231.

Technical Abstract: While plant canopies are important controllers over water and carbon fluxes between the biosphere and atmosphere, in water limited ecosystems soils have important direct and indirect effects on ecosystem fluxes. Using whole-ecosystem assessments of water and carbon exchanges in large plots exposed to different precipitation regimes, we have attempted to understand how individual rainfall events and characteristics of precipitation in time influence exchange processes. Since precipitation is an important trigger for biological and physical processes that result in exchange, how soils translate rainfall into biologically available water affects microbially-mediated carbon cycling and potential plant activity. Additionally, the expanse of bare-ground area and microclimate characteristics can influence the relative importance of transpiration versus evaporation following rainfall events. Because physical processes, such as gas displacement by infiltrating water, occur quicker than photosynthetic upregulation by plants, semi-arid and arid ecosystems are often immediate sources of carbon to the atmosphere following rainfall events and only become sinks should water persist in the rooting zone for sufficient time to allow for plant activity. In general, characteristics of rainfall, such as frequency and magnitude influence ecosystem processes primarily by controlling the duration of process rather than the maximum rate of activity. Understanding such controllers is important to mechanistically modeling biosphere / atmosphere exchange in water limited ecosystems.