Climatic and non-climatic vegetation cover changes in the rangelands of Africa

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About 21% of the African population directly depends on rangeland resources. As this number is predicted to grow, it is important to understand the response of African rangelands to global environmental change and formulate, in turn, better hypotheses on their capacity to support livelihoods. Here we used three decades of satellite data and a dynamic global vegetation model to study the response of rangeland vegetation to recent climate change and to describe changes in the vegetation structure accompanying greening and browning trends. Long-term climate change was the dominant driver of vegetation dynamics in ca. 2,495,000 km2 of African rangelands (22.7% of the total extent). Examples of these rangelands are in Mauritania, Senegal, Chad, Namibia, Botswana, and South Africa, where the vegetation greened up due to an overall increase in trees, shrubs, and short herbaceous vegetation. We further identified a more extended different type of rangeland (ca. 2,915,000 km2) where vegetation dynamics appeared to be largely unrelated to long-term climate variations. In these rangelands, we observed opposite trends between woody cover (trees and shrubs) and short vegetation (mostly representative of the herbaceous layer). Greening (West Africa, South Sudan) was associated with an overall increase in woody cover (+4.4%) and a concomitant decline in short vegetation (−3.4%), while browning (Angola, Mozambique) resulted from a decrease in woody cover (−2.6%) and an increase in short vegetation (+4.3%) (total per cent change average during 1982–2015). Our results offer a nuanced perspective to frame greening and browning trends in rangeland systems. While greening may mitigate climate change via higher carbon uptake, the encroachment of less palatable woody species reduces the resources available to pastoral communities. On the other hand, browning due to a reduction in the woody cover attenuates carbon sequestration rates, but the observed increase in short herbaceous vegetation may hint a relative increase in forage resources.

Original languageEnglish
Article number103516
JournalGlobal and Planetary Change
Number of pages13
Publication statusPublished - Jul 2021

Bibliographical note

Funding Information:
We thank all research groups that produced and shared the datasets used in this study. We thank JP Guzman for the support with R Studio; F Detsch for addressing the use of the CRAN package ‘gimms’; J Sheffield for the suggestions on quality controls; LA Brown, C Abel, R Fensholt, and S Horion for the discussions. FD was partly funded by the European Cooperation in Science and Technology (COST) Action CA16233 ‘Drylands facing change: interdisciplinary research on climate change, food insecurity, political instability’. MB was funded by an AXA research grant and a DFF Sapere Aude grant.

Publisher Copyright:
© 2021 Elsevier B.V.

    Research areas

  • DGVM, Pastoral welfare, Rangeland dynamic, Remote sensing, Trend analysis, Vegetation composition

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