HR: 14:40h
AN: B43F-05    [Abstracts]
TI: Interannual Variability in FPAR and NPP across California­_s Ecosystems
AU: * Jin, Y
EM: yufang@uci.edu
AF: University of California, Irvine, Department of Earth System Science, Irvine, CA 92697-3100 United States
AU: Goulden, M L
EM: mgoulden@uci.edu
AF: University of California, Irvine, Department of Earth System Science, Irvine, CA 92697-3100 United States
AU: Randerson, J T
EM: jranders@uci.edu
AF: University of California, Irvine, Department of Earth System Science, Irvine, CA 92697-3100 United States
AB: Quantifying the response of ecosystems to climate is particularly important for understanding California­_s regional carbon budget because of large year-to-year changes in precipitation and because of large changes in temperature and precipitation that are predicted to occur across the western U.S. during the 21st century. Here, we examined how net primary production (NPP) varies with precipitation and how this ecosystem process contributes to the changes in carbon storage on interannual timescales. We used FPAR derived from NOAA AVHRR satellite observations during 1982-2003 and from MODIS observations during 2000-2005 as inputs to the CASA biogeochemical model. We found that mean annual integrals of NDVI, FPAR, and NPP were closely linked with mean annual precipitation levels across the state. The sensitivity of NPP to interannual variability in precipitation depended on ecosystem type. Desert shrub and grassland ecosystems responded the most to interannual changes in precipitation, whereas forests showed little or no response. In semiarid ecosystems, the site-level temporal sensitivity of NPP to variations in precipitation was found to be lower than the sensitivity of NPP to precipitation derived from a spatial model, suggesting that other constraints such as plant structure or nitrogen availability may limit NPP responses to short-term precipitation transients.
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0480 Remote sensing
SC: Biogeosciences [B]
MN: Fall Meeting 2005