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Waxing and waning of forests: Late Quaternary biogeography of southeast Africa
- Source :
- Global Change Biology, Global Change Biology, Wiley, 2018, 24 (7), pp.2939-2951. ⟨10.1111/gcb.14150⟩, Global Change Biology, 2018, 24 (7), pp.2939-2951. ⟨10.1111/gcb.14150⟩
- Publication Year :
- 2018
- Publisher :
- HAL CCSD, 2018.
-
Abstract
- International audience; African ecosystems are at great risk. Despite their ecological and economic importance, long‐standing ideas about African forest ecology and biogeography, such as the timing of changes in forest extent and the importance of disturbance, have been unable to be tested due to a lack of sufficiently long records. Here, we present the longest continuous terrestrial record of late Quaternary vegetation from southern Africa collected to date from a drill core from Lake Malawi covering the last ~600,000 years. Pollen analysis permits us to investigate changes in vegetation structure and composition over multiple climatic transitions. We observe nine phases of forest expansion and collapse related to regional hydroclimate change. The development of desert, steppe and grassland vegetation during arid periods is likely dynamically linked to thresholds in regional hydrology associated with lake level and moisture recycling. Species composition of these dryland ecosystems varied greatly and is unlike the vegetation found at Malawi today, with assemblages suggesting strong Somali‐Masai affinities. Furthermore, nearly all semiarid assemblages contain low forest taxa abundances, suggesting that moist lowland gallery forests formed refugia along waterways during arid times. When the region was wet, forests were species‐rich and very high afromontane tree abundances suggest frequent widespread lowland colonization by modern high elevation trees. Furthermore, species composition varied little amongst forest phases until ~80 ka when disturbance tolerant tree taxa characteristic of the modern vegetation increased in abundance. The waxing and waning of forests has important implications for understanding the processes that control modern tropical vegetation biogeography as well as the environments of early humans across Africa. Finally, this work highlights the resilience of montane forests during previous warm intervals, which is relevant for future climate change; however, we point to a fundamental shift in disturbance regimes which are crucial for the structure and composition of modern East African landscapes.
- Subjects :
- 0106 biological sciences
010504 meteorology & atmospheric sciences
Steppe
Climate Change
Biogeography
hydrology
[PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]
Forests
010603 evolutionary biology
01 natural sciences
palaeoclimate
Trees
Forest ecology
Tropical vegetation
Humans
Environmental Chemistry
biogeography
global change
0105 earth and related environmental sciences
General Environmental Science
tropical forests
Global and Planetary Change
geography
geography.geographical_feature_category
Ecology
Gallery forest
Vegetation
15. Life on land
Biological Evolution
Arid
Disturbance (ecology)
13. Climate action
palaeoenvironments
Lake Malawi
Africa
Subjects
Details
- Language :
- English
- ISSN :
- 13541013 and 13652486
- Database :
- OpenAIRE
- Journal :
- Global Change Biology, Global Change Biology, Wiley, 2018, 24 (7), pp.2939-2951. ⟨10.1111/gcb.14150⟩, Global Change Biology, 2018, 24 (7), pp.2939-2951. ⟨10.1111/gcb.14150⟩
- Accession number :
- edsair.doi.dedup.....872beb6bc81966889c9df43462170836