Phenological Variation in Habitat Type Inferred from High-Resolution Satellite Imagery in a Diversely Managed Conservation Landscape

Le résumé fourni par la source

Large herbivore (>100 kg) species are globally threatened by the combined impacts of climate change, hunting, and habitat loss as a consequence of human land use. These species play important ecological roles, and their loss from ecosystems often triggers a cascade of negative consequences, for both ecosystems and humans. In northern Namibia, above-average warming is predicted to increase the occurrence of droughts, heatwaves, and similar extreme weather events that detrimentally impact ecosystem structure and function. Understanding how such ecosystem changes drive or impact large herbivore populations requires detailed examination of their habitat. Satellite observations have been combined with GPS telemetry to examine environmental and vegetative influences on movement ecology in the past; however, the spatial scales of investigation are relatively coarse (e.g. 500 m pixel size). New remote sensing data streams provide improved opportunities for understanding fine-scale drivers of animal movement. In this study we use multispectral satellite imagery with high spatial resolution (∼3 m) and temporal frequency (daily revisits) to map heterogeneity in vegetation cover across a 1000 km2 area centred on the Etosha Heights Private Reserve in northern Namibia. Annual timeseries of the Enhanced Vegetation Index (EVI) and Soil Adjusted Vegetation Index (SAVI) demonstrate clear differences in the timing and seasonal amplitude of vegetation activity of key land cover types identified from detailed field surveys. We explore the utility of phenological metrics for mapping fine-scale land cover in this region, and also for understanding movement ecology of large herbivores across a diversely managed multiple-use landscape.

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