Accelerating land cover change in West Africa over four decades as population pressure increased

Stefanie M Herrmann,Martin Brandt,Rasmus Fensholt,Kjeld Rasmussen

doi:10.1038/s43247-020-00053-y

Stefanie M Herrmann, Martin Brandt + Show 2 more

Open Access

https://doi.org/10.1038/s43247-020-00053-y

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Abstract

Rapid population growth in West Africa has exerted increasing pressures on land resources, leading to observable changes in the land cover and land use. However, spatially explicit and thematically detailed quantitative analyses of land cover change over long time periods and at regional scale have been lacking. Here we present a change intensity analysis of a Landsat-based, visually interpreted, multi-date (1975, 2000, 2013) land cover dataset of West Africa, stratified into five bioclimatic sub-regions. Change intensities accelerated over time and increased from the arid to the sub-humid sub-regions, as did population densities. The area occupied by human-dominated land cover categories more than doubled from 493,000 km2 in 1975 to 1,121,000 km2 in 2013. Land cover change intensities within 10 km of new settlement locations exceeded the region-wide average by up to a factor of three, substantiating the significant role of population pressure as a force of change. The spatial patterns of the human footprint in West Africa, however, suggest that not only population pressure but also changing socioeconomic conditions and policies shape the complexity of land cover outcomes.

Highlights

Rapid population growth in West Africa has exerted increasing pressures on land resources, leading to observable changes in the land cover and land use
We stratified the vast and geographically diverse study region into six sub-regions defined by their mean annual precipitation (Fig. 1c) to highlight the variety of land cover compositions and dynamics along the precipitation gradient
Particular emphasis was placed on land cover changes associated with the expansion of settlements as a proxy for increasing population pressure (Fig. 1c)

Summary

Introduction

Rapid population growth in West Africa has exerted increasing pressures on land resources, leading to observable changes in the land cover and land use. Land cover change intensities within 10 km of new settlement locations exceeded the region-wide average by up to a factor of three, substantiating the significant role of population pressure as a force of change. The spatial patterns of the human footprint in West Africa, suggest that population pressure and changing socioeconomic conditions and policies shape the complexity of land cover outcomes. The landscapes of West Africa have had a millennia-long history of human settlement, natural resource exploitation and development, and as a result they are very much anthropogenic landscapes[12,13], where origins of agriculture date back an estimated 4000–5000 years[8]. Local-scale studies from the region hint to rural population growth as an important driver for cropland expansion in semiarid southern Burkina Faso[16] and northern Ghana[17]

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