The contribution of C3 and C4 grasses to interannual variability in time-integrated NDVI over the U.S. Great Plains

Time integrated normalized difference vegetation index (ΣNDVI) derived from NOAA AVHRR multitemporal imagery over a 10-yr period (1989-1998) was used as a surrogate for primary production to investigate the impact of interannual climate variability on grassland performance for central and northern U.S. Great Plains. First, the contribution of C₃ and C₄ species abundances to the major grassland ecosystems of the U.S. Great Plains is described. Next, the relation between mean ΣNDVI and the ΣNDVI coefficient of variation (CV ΣNDVI) used as a proxi for interannual climate variability is analyzed. Results suggest that the differences in the long-term climatic control over ecosystem performance approximately coincide with changes between C₃- and C₄-dominant grassland classes. Variation in remotely sensed net primary production over time is higher for the southern and western plains grasslands (primarily C4 grasslands), whereas the C₃-dominated classes in the northern and eastern portion of the U.S. Great Plains generally show lower CV ΣNDVI values.