Modelling habitat suitability in the Green Sahara using a quantitative proxy-based paleoclimate reconstruction

Abstract

This study uses published paleoclimate proxy data to develop an accurate climate surface for North Africa and the Arabian Peninsula during the mid-Holocene (approximately 6 ka). The result is a paleoclimate surface of 2x2 degree resolution composed of four climate variables: mean annual temperature, mean annual precipitation, and mean temperature of the warmest and coldest months. This is a novel and useful resource for modelling habitat suitability in the Green Sahara, and is appropriate for application in regional-scale habitat modelling.

This climate surface is used to model habitat suitability for three species using a maximum entropy modelling approach: the sand cat (Felis margarita), an obligate desert species; the Dama gazelle (Nanger dama), a Sahel specialist; and the African wildcat (Felis silvestris lybica), a generalist species. Habitat models for the Dama gazelle act as a proxy for Sahelian environments; while vegetated grassland likely dominated the geography of northern Africa during the mid-Holocene, the climate was not precisely analogous to the modern Sahel. Suitable habitat for the sand cat during the mid-Holocene was limited to possible refugia in Egypt, Morocco and central Saudi Arabia, all likely occupied by the African wildcat at this time. As modern habitat suitability models indicate large regions of overlap between the species in the present day, competition from the wildcat may not have been significantly detrimental to the sand cat population. In addition, sand cat populations in northern Africa, Arabia, and Asia were likely isolated during Green Sahara periods due to restricted habitat availability.