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Impact of vegetation greening on carbon and water cycle in the African Sahel-Sudano-Guinean region

Impact of vegetation greening on carbon and water cycle in the African Sahel-Sudano-Guinean region
Impact of vegetation greening on carbon and water cycle in the African Sahel-Sudano-Guinean region

The African Sahel-Sudano-Guinean region is one of the largest water limited environments in the world, thus making it highly vulnerable to climate change. Recent studies have shown vegetation greening in the region, but few have investigated the impact of this greening on carbon and water cycles. We used a combination of earth observation (EO) data and a diagnostic model to evaluate the extent of the vegetation greening and its impacts on carbon sequestration potential (i.e., Gross Primary Productivity-GPP) and the water cycle (i.e., Evapotranspiration-ET and Water Use Efficiency-WUE) from 1982 to 2015. Additionally, we evaluated the influence of key climatic variables (i.e., precipitation, temperature, and solar radiation) on vegetation greening, carbon sequestration potential and the water cycle. Our results showed widespread vegetation greening during the first half of the study period (1982–2000), driven mainly by increase in precipitation. However, the rate of greening reduced or became stagnant during the latter half of the study (2000–2015), but did not revert to pre-greening levels of 1980s, implying a persistent ecosystem change. The vegetation greening and increased precipitation resulted in a ~ 17.95% increase in GPP (from ~3.9 PgC/year in 1982 to ~4.6 PgC/year in 2000) and a ~ 21.28% increase in ET (from ~47 mm/year in 1982 to ~57 mm/year in 2015). The WUE showed an overall reduction, mainly attributed to large increases in ET not matched by similar magnitude of increases in GPP. Currently, there is lack of consensus on the magnitude of the contribution of drylands to the global carbon and water cycle. This study shows that drylands undergoing ecosystem change, coupled with climate change, may in future become important contributors to the global carbon and water cycle. Therefore, they could play a key role in future global warming and climate change mitigation strategies.

Carbon sequestration, Gross primary productivity, SCARF model, Vegetation greening, Water use efficiency
0921-8181
Ogutu, Booker
4e36f1d2-f417-4274-8f9c-4470d4808746
Dash, Jadunandan
51468afb-3d56-4d3a-aace-736b63e9fac8
D'adamo, Francesco
e8fbd2c1-d455-47ce-aa34-5b0f8d4259bf
Ogutu, Booker
4e36f1d2-f417-4274-8f9c-4470d4808746
Dash, Jadunandan
51468afb-3d56-4d3a-aace-736b63e9fac8
D'adamo, Francesco
e8fbd2c1-d455-47ce-aa34-5b0f8d4259bf

Ogutu, Booker, Dash, Jadunandan and D'adamo, Francesco (2021) Impact of vegetation greening on carbon and water cycle in the African Sahel-Sudano-Guinean region. Global and Planetary Change, 202, [103524]. (doi:10.1016/j.gloplacha.2021.103524).

Record type: Article

Abstract

The African Sahel-Sudano-Guinean region is one of the largest water limited environments in the world, thus making it highly vulnerable to climate change. Recent studies have shown vegetation greening in the region, but few have investigated the impact of this greening on carbon and water cycles. We used a combination of earth observation (EO) data and a diagnostic model to evaluate the extent of the vegetation greening and its impacts on carbon sequestration potential (i.e., Gross Primary Productivity-GPP) and the water cycle (i.e., Evapotranspiration-ET and Water Use Efficiency-WUE) from 1982 to 2015. Additionally, we evaluated the influence of key climatic variables (i.e., precipitation, temperature, and solar radiation) on vegetation greening, carbon sequestration potential and the water cycle. Our results showed widespread vegetation greening during the first half of the study period (1982–2000), driven mainly by increase in precipitation. However, the rate of greening reduced or became stagnant during the latter half of the study (2000–2015), but did not revert to pre-greening levels of 1980s, implying a persistent ecosystem change. The vegetation greening and increased precipitation resulted in a ~ 17.95% increase in GPP (from ~3.9 PgC/year in 1982 to ~4.6 PgC/year in 2000) and a ~ 21.28% increase in ET (from ~47 mm/year in 1982 to ~57 mm/year in 2015). The WUE showed an overall reduction, mainly attributed to large increases in ET not matched by similar magnitude of increases in GPP. Currently, there is lack of consensus on the magnitude of the contribution of drylands to the global carbon and water cycle. This study shows that drylands undergoing ecosystem change, coupled with climate change, may in future become important contributors to the global carbon and water cycle. Therefore, they could play a key role in future global warming and climate change mitigation strategies.

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Impact of vegetation greening on carbon and water cycle in the African Sahel-Sudano-Guinean region - Accepted Manuscript
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Accepted/In Press date: 20 May 2020
Published date: 24 May 2021
Additional Information: Funding Information: We would like to acknowledge the data providers including: the NASA GIMMS group for the NDVI3g.v1 dataset, the ESA CCI for the Land cover data, CARBOAFRICA for the flux tower data, FAO for the aridity index maps, Climate Hazard Centre for CHIRPS data, National Terradynamic Simulation Group (NTSG), University of Montana for the Evapotranspiration data, the University of Delaware for Temperature data, Climatology Lab at the University of Idaho for the VPD, PAR, temperature data, EUMETSAT for the solar radiation data, and the Centre for Global Change Data Processing and Analysis of Beijing Normal University, Beijing, China for the GLASS AVHRR FAPAR data. Publisher Copyright: © 2021 Elsevier B.V. Copyright: Copyright 2021 Elsevier B.V., All rights reserved.
Keywords: Carbon sequestration, Gross primary productivity, SCARF model, Vegetation greening, Water use efficiency

Identifiers

Local EPrints ID: 450366
URI: http://eprints.soton.ac.uk/id/eprint/450366
ISSN: 0921-8181
PURE UUID: abe18f8a-0962-44e3-81b6-8bccc6212f9b
ORCID for Booker Ogutu: ORCID iD orcid.org/0000-0002-1804-6205
ORCID for Jadunandan Dash: ORCID iD orcid.org/0000-0002-5444-2109
ORCID for Francesco D'adamo: ORCID iD orcid.org/0000-0003-4428-0713

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Date deposited: 26 Jul 2021 16:31
Last modified: 30 Oct 2023 05:56

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Contributors

Author: Booker Ogutu ORCID iD
Author: Jadunandan Dash ORCID iD
Author: Francesco D'adamo ORCID iD

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