title: Environmental hydro-refugia demonstrated by vegetation vigour in the Okavango Delta, Botswana.
abstract: Climate shifts at decadal scales can have environmental consequences, and therefore, identifying areas that act as environmental refugia is valuable in understanding future climate variability. Here we illustrate how, given appropriate geohydrology, a rift basin and its catchment can buffer vegetation response to climate signals on decadal time-scales, therefore exerting strong local environmental control. We use time-series data derived from Normalised Difference Vegetation Index (NDVI) residuals that record vegetation vigour, extracted from a decadal span of MODIS images, to demonstrate hydrogeological buffering. While this has been described previously it has never been demonstrated via remote sensing and results in relative stability in vegetation vigour inside the delta, compared to that outside. As such the Delta acts as a regional hydro-refugium. This provides insight, not only to the potential impact of future climate in the region, but also demonstrates why similar basins are attractive to fauna, including our ancestors, in regions like eastern Africa. Although vertebrate evolution operates on time scales longer than decades, the sensitivity of rift wetlands to climate change has been stressed by some authors, and this work demonstrates another example of the unique properties that such basins can afford, given the right hydrological conditions.
authors: Institute for Studies in Landscape and Human Evolution, Faculty of Science and Technology, Bournemouth University, Fern Barrow, Poole, BH12 5BB, UK.
authors: S C
authors: SC
authors: Reynolds
authors: Nottingham University, University Park, Nottingham, NG7 2RD, UK.|Edge Hill University, Ormskirk Campus, Ormskirk, L39 4QP, UK.
authors: C G
authors: CG
authors: Marston
authors: Institute for International Energy Studies, Tehran 1967743711, Iran.
authors: H
authors: H
authors: Hassani
authors: Laboratoire de Tectonique, Institut de Physique du Globe de Paris, Paris Cedex 05, France.
authors: G C P
authors: GC
authors: King
authors: Institute for Studies in Landscape and Human Evolution, Faculty of Science and Technology, Bournemouth University, Fern Barrow, Poole, BH12 5BB, UK.
authors: M R
authors: MR
authors: Bennett