Interannual variability of NDVI and species richness in Kenya

Ecologists have long recognized the spatial variability of species richness . In an attempt to identify the factors responsible for this variability, e cologists have traditionally used environmental data obtained from sparse p oint samples (such as meteorological stations). However, remotely sensed da ta also provide a means of estimating relevant environmental factors and th ereby improving predictions of species richness. The Advanced Very High Res olution Radiometer Normalized Difference Vegetation Index (AVHRR NDVI) has been shown to be related to net primary productivity (NPP) and actual evapo transpiration ( AET) for many vegetation types. NPP and AET have frequently been used as surrogate measures for species richness. Local spatial variab ility of NPP and AET, indicating habitat heterogeneity, is hypothesized as another influence on species richness. We examined the relationship between interannual maximum NDVI parameters and species richness of vascular plant s and mammals. The study was done at a landscape scale, which matches the s cale of data collection. Statistical analyses revealed that higher average NDVI results in lower species richness, whereas standard deviation and coef ficient of variation correlated positively with species richness. Thus, NDV I parameters appear to represent environmental factors influencing species richness. Hence, by utilizing remote sensing, our understanding of the spat ial variability of species richness was improved.