Modelling biome shifts and tree cover change for 2050 in West Africa
Article first published online: 21 JUN 2011
© 2011 Blackwell Publishing Ltd
Journal of Biogeography
Volume 38, Issue 12, pages 2248–2258, December 2011
How to Cite
Heubes, J., Kühn, I., König, K., Wittig, R., Zizka, G. and Hahn, K. (2011), Modelling biome shifts and tree cover change for 2050 in West Africa. Journal of Biogeography, 38: 2248–2258. doi: 10.1111/j.1365-2699.2011.02560.x
- Issue published online: 15 NOV 2011
- Article first published online: 21 JUN 2011
- bioclimatic envelope models;
- climate change;
- forest degradation;
- generalized additive model;
- human impact;
- species distribution modelling
Aim Africa is expected to face severe changes in climatic conditions. Our objectives are: (1) to model trends and the extent of future biome shifts that may occur by 2050, (2) to model a trend in tree cover change, while accounting for human impact, and (3) to evaluate uncertainty in future climate projections.
Location West Africa.
Methods We modelled the potential future spatial distribution of desert, grassland, savanna, deciduous and evergreen forest in West Africa using six bioclimatic models. Future tree cover change was analysed with generalized additive models (GAMs). We used climate data from 17 general circulation models (GCMs) and included human population density and fire intensity to model tree cover. Consensus projections were derived via weighted averages to: (1) reduce inter-model variability, and (2) describe trends extracted from different GCM projections.
Results The strongest predicted effect of climate change was on desert and grasslands, where the bioclimatic envelope of grassland is projected to expand into the desert by an area of 2 million km2. While savannas are predicted to contract in the south (by 54 ± 22 × 104 km2), deciduous and evergreen forest biomes are expected to expand (64 ± 13 × 104 km2 and 77 ± 26 × 104 km2). However, uncertainty due to different GCMs was particularly high for the grassland and the evergreen biome shift. Increasing tree cover (1–10%) was projected for large parts of Benin, Burkina Faso, Côte d’Ivoire, Ghana and Togo, but a decrease was projected for coastal areas (1–20%). Furthermore, human impact negatively affected tree cover and partly changed the direction of the projected change from increase to decrease.
Main conclusions Considering climate change alone, the model results of potential vegetation (biomes) show a ‘greening’ trend by 2050. However, the modelled effects of human impact suggest future forest degradation. Thus, it is essential to consider both climate change and human impact in order to generate realistic future tree cover projections.