, Volume 6, Issue 3, pp 401-422

Are biodiversity ‘hotspots’ correlated with current ecoclimatic stability? A pilot study using the NOAA-AVHRR remote sensing data

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The GAC (Global Area Coverage) by the NOAA-AVHRR satellites represents an excellent data set for studying global and regional patterns of variations in surface conditions driven in part by climatic variation. In this pilot study we examined whether biodiversity ‘hotspots’, defined from peak concentrations of neoendemics as well as geographically relict forms, differ in ecoclimatic stability from surrounding areas under present-day climatic conditions. Coefficients of variation of the ratio between brightness surface temperature (Ts) and the Normalized Difference Vegetation Index (NDVI) based upon 10 years' monthly composited scenes of tropical Africa revealed distinctive geographical patterns of interannual variability in surface conditions. Regions with a predominance of old species are characterized by spatial uniformity in the ecoclimatic variability, while regions where rapidly radiating groups dominate are spatially complex in this respect. However, the exact ‘hotspots’, with peak concentrations of endemic species, are characterized by a local reduction in ecoclimatic variability, or placement on the boundary to a stable region. This relationship was supported statistically by comparing ecoclimatic profiles across montane forests representing ‘hotspots’, and those of other montane forests. It is suggested that, because of interactions between prevailing atmospheric flows, topography and vegetation, the impact of extreme weather is moderated locally. The correlation between current stability and aggregates of neoendemics as well as old relics indicate that local moderation of climatic extremes persist through shifting climatic periods, permitting populations of unique species to survive in these places. The results are used to identify study sites for better ground truthing and for paleoclimatological studies which may be useful for more thorough studies of these relationships.