HR: 1330h
AN: B22A-0800    [PDF]
TI: Spatial and temporal variability in carbon flux and its correlation with canopy level vegetation indices
AU: * Hastings, S J
EM: shasting@sunstroke.sdsu.edu
AF: Global Change Research Group, San Diego State University, San Diego, CA 92182-4614 United States
AU: Oechel, W C
EM: oechel@sunstroke.sdsu.edu
AF: Global Change Research Group, San Diego State University, San Diego, CA 92182-4614 United States
AU: Gamon, J A
EM: jgamon@calstatela.edu
AF: Department of Biological Sciences, California State University, Los Angles, Los Angles, CA 90032 United States
AU: Salinas, C
AF: Centro de Investigaciones Biol¢gicas del Noroeste, S.C., Mar Bermejo No. 195, Col. Playa Palo de Santa Rita, Apdo. Postal 128, La Paz, BCS 23090 Mexico
AB: The temporal variability of carbon and water flux of a sarcocaulescent desert shrub ecosystem from July 2001 to September 2003 as measured using the eddy covariance technique in La Paz, Baja California Sur, Mex are described. Our objective was to link site specific measurements of net ecosystem flux with both canopy and satellite remote sensing measurements. Initially, using daily mid day web cam photos, patterns of phenological development and the rate of carbon uptake or loss were found to be linked with the timing and amount of rainfall. When seasonal rains began earlier than normal (2001), loss of carbon via soil respiration was observed with no development of the photosynthetic canopy. Upon the onset of the historical rainy season for the area, seasonal maximum values of net ecosystem flux (-1.5 vs -0.7 gC m$^{-2}$ day$^{-1}$ in 2001 and 2002 respectively) was strongly correlated with the amount of rainfall in 2001 and 2002 with precipitation in 2001 approximately twice as large as in 2002 (338 mm vs 124 mm). Spatially explicit measurements of soil respiration and canopy level normalized difference vegetation index were initiated in April of 2003. Mid August rains in 2003 resulted in the anticipated response of the vegetation with respect to development of the canopy. Using the spatial patterns of soil respiration and canopy level NDVI coupled with soil moisture and root biomass sampling, root development was shown to make up a large portion of ecosystem respiration upon the onset of the seasonal rains in 2003. These results are compared with 21 years of regional AVHRR and precipitation for the area as well as MODIS remote sensing outputs.
DE: 0614 Biological effects
DE: 1866 Soil moisture
DE: 3360 Remote sensing
DE: 4227 Diurnal, seasonal, and annual cycles
DE: 4815 Ecosystems, structure and dynamics
SC: Biogeosciences [B]
MN: 2003 Fall Meeting