The role of C3 and C4 grasses to interannual variability in remotely sensed ecosystem performance over the US Great Plains

Time integrated normalized difference vegetation index (SigmaNDVI) derived from National Oceanic and Atmospheric Administration (NOAA) Advanced Very High Resolution Radiometer (AVHRR) multi-temporal imagery over a 10-year 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 US Great Plains. First, the contribution of C-3 and C-4 species abundance to the major grassland ecosystems of the US Great Plains is described. Next, the relation between mean SigmaNDVI and the SigmaNDVI coefficient of variation (CV SigmaNDVI) used as a proxy for interannual climate variability is analysed. Results suggest that the differences in the long-term climatic control over ecosystem performance approximately coincide with changes between C-3- and C-4-dominant grassland classes. Variation in remotely sensed net primary production over time is higher for the southern and western plains grasslands (primarily C-4 grasslands), whereas the C-3-dominated classes in the northern and eastern portion of the US Great Plains, generally show lower CV SigmaNDVI values.