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Vegetation Controls on Weathering Intensity during the Last Deglacial Transition in Southeast Africa
- Source :
- PLoS ONE, PLoS ONE, Public Library of Science, 2014, 9 (11), pp.e112855. ⟨10.1371/journal.pone.0112855⟩, PLoS ONE, 2014, 9 (11), pp.e112855. ⟨10.1371/journal.pone.0112855⟩, PLoS ONE, Public Library of Science, 2014, 9 (11), pp.e112855 ⟨10.1371/journal.pone.0112855⟩, PLoS ONE, Vol 9, Iss 11, p e112855 (2014)
- Publication Year :
- 2014
- Publisher :
- HAL CCSD, 2014.
-
Abstract
- International audience; Tropical climate is rapidly changing, but the effects of these changes on the geosphere are unknown, despite a likelihood of climatically-induced changes on weathering and erosion. The lack of long, continuous paleo-records prevents an examination of terrestrial responses to climate change with sufficient detail to answer questions about how systems behaved in the past and may alter in the future. We use high-resolution records of pollen, clay mineralogy, and particle size from a drill core from Lake Malawi, southeast Africa, to examine atmosphere-biosphere-geosphere interactions during the last deglaciation (,18–9 ka), a period of dramatic temperature and hydrologic changes. The results demonstrate that climatic controls on Lake Malawi vegetation are critically important to weathering processes and erosion patterns during the deglaciation. At 18 ka, afromontane forests dominated but were progressively replaced by tropical seasonal forest, as summer rainfall increased. Despite indication of decreased rainfall, drought-intolerant forest persisted through the Younger Dryas (YD) resulting from a shorter dry season. Following the YD, an intensified summer monsoon and increased rainfall seasonality were coeval with forest decline and expansion of drought-tolerant miombo woodland. Clay minerals closely track the vegetation record, with high ratios of kaolinite to smectite (K/S) indicating heavy leaching when forest predominates, despite variable rainfall. In the early Holocene, when rainfall and temperature increased (effective moisture remained low), open woodlands expansion resulted in decreased K/S, suggesting a reduction in chemical weathering intensity. Terrigenous sediment mass accumulation rates also increased, suggesting critical linkages among open vegetation and erosion during intervals of enhanced summer rainfall. This study shows a strong, direct influence of vegetation composition on weathering intensity in the tropics. As climate change will likely impact this interplay between the biosphere and geosphere, tropical landscape change could lead to deleterious effects on soil and water quality in regions with little infrastructure for mitigation. This is an open-access article, free of all copyright, and may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose. The work is made available under the Creative Commons CC0 public domain dedication. Data Availability: The authors confirm that all data underlying the findings are fully available without restriction. All relevant data are within the paper and its Supporting Information files. Funding: Lake Malawi Drilling Project-Earth System History Program (NSF-EAR-0602404) funded field operations, logistics, and some laboratory analysis. NSF Graduate Research Fellowship (2009078688) provided student salary and tuition and some travel support for laboratory analysis. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist.
- Subjects :
- Geologic Sediments
Malawi
010504 meteorology & atmospheric sciences
Rain
lcsh:Medicine
Marine and Aquatic Sciences
Limnogeology
Woodland
010502 geochemistry & geophysics
01 natural sciences
CARBON-DIOXIDE
X-Ray Diffraction
Global Change Ecology
Tropical climate
Dry season
Limnology
lcsh:Science
Kaolin
History, Ancient
Sedimentary Geology
Multidisciplinary
CLIMATE-CHANGE
Geography
Ecology
[SDE.IE]Environmental Sciences/Environmental Engineering
POLLEN
Geology
Vegetation
Biodiversity
TANZANIA
Biogeography
Erosion
Aluminum Silicates
Research Article
LAKE MALAWI
Forest Ecology
TROPICAL EAST-AFRICA
Climate Change
[SDE.MCG]Environmental Sciences/Global Changes
Climate change
TANGANYIKA
Biology
Species Specificity
Paleoclimatology
Deglaciation
Paleobotany
GLACIAL MAXIMUM
Younger Dryas
Paleolimnology
Particle Size
Terrestrial Ecology
Plant Physiological Phenomena
0105 earth and related environmental sciences
Tropical Climate
LATE QUATERNARY
Silicates
lcsh:R
Ecology and Environmental Sciences
Biology and Life Sciences
Paleontology
Geomorphology
15. Life on land
[SDE.ES]Environmental Sciences/Environmental and Society
Lakes
13. Climate action
RAINFALL SEASONALITY
Earth Sciences
Clay
lcsh:Q
Physical geography
Paleoecology
Paleobiology
[SDE.BE]Environmental Sciences/Biodiversity and Ecology
Subjects
Details
- Language :
- English
- ISSN :
- 19326203
- Database :
- OpenAIRE
- Journal :
- PLoS ONE, PLoS ONE, Public Library of Science, 2014, 9 (11), pp.e112855. ⟨10.1371/journal.pone.0112855⟩, PLoS ONE, 2014, 9 (11), pp.e112855. ⟨10.1371/journal.pone.0112855⟩, PLoS ONE, Public Library of Science, 2014, 9 (11), pp.e112855 ⟨10.1371/journal.pone.0112855⟩, PLoS ONE, Vol 9, Iss 11, p e112855 (2014)
- Accession number :
- edsair.doi.dedup.....36fd19acd262b649949c2b7cc2c4274f