Knowledge Resource Center for Ecological Environment in Arid Area
DOI | 10.1016/j.rse.2013.09.011 |
Re-greening Sahel: 30 years of remote sensing data and field observations (Mali, Niger) | |
Dardel, C.1; Kergoat, L.1; Hiernaux, P.1; Mougin, E.1; Grippa, M.1; Tucker, C. J.2 | |
通讯作者 | Dardel, C. |
来源期刊 | REMOTE SENSING OF ENVIRONMENT
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ISSN | 0034-4257 |
EISSN | 1879-0704 |
出版年 | 2014 |
卷号 | 140页码:350-364 |
英文摘要 | Desertification of the Sahel region has been debated for decades, while the concept of a "re-greening" Sahel appeared with satellite remote sensing data that allowed vegetation monitoring across wide regions and over increasingly long series of years (nowadays 30 years with the GIMMS-3g dataset). However, the scarcity of long-term field observations of vegetation in the Sahel prevents ground validation and deeper analysis of such trends. After assessing the consistency of the new GIMMS-3g NDVI product by comparison to three other AVHRR-NDVI datasets and MODIS NDVI, regional GIMMS-3g NDVI trends over 1981-2011 are analyzed. Trends are found positive and statistically significant almost everywhere in Sahel over the 1981-2011 period. Long-term field observations of the aboveground herbaceous layer mass have been collected within the Gourma region in Mali (1984-2011) and within the Fakara region in western Niger (1994-2011). These observations sample ecosystem and soil diversity, thus enabling estimation of averaged values representative of the Gourma and Fakara. NDVI measurements are found in good agreement with field observations, both over the Gourma and Fakara regions where re-greening and negative trends are observed respectively. A linear regression analysis performed between spatially averaged seasonal NDVI and a weighted average of field measurements explains 59% of the variability for the Gourma region over 1984-2011, and 38% for the Fakara region over 1994-2011. In the Gourma, which is a pastoral region, the re-greening trend is mainly observed over sandy soils, and attests for the ecosystem’s resilience to the 1980s’ drought, able to react to the more favorable rainfall of the 1990s and 2000s. However, contrasted changes in the landscape’s functioning have occurred locally. An increase in erosion and run-off processes in association with decreasing or stable vegetation cover was observed over shallow soils, which occupy 30% of the area. In the agro-pastoral Fakara, the decreasing trends observed both from satellite NDVI and field assessments of herbaceous mass are hardly explained by rainfall. These results give confidence in the dominant positive trends in Sahelian greenness, but indicate that degradation trends can also be observed, both in situ and from satellite time series. (C) 2013 Elsevier Inc. All rights reserved. |
英文关键词 | Sahel Desertification Re-greening Trend analysis Herbaceous production NDVI AVHHR Field measurements Mali Niger |
类型 | Article |
语种 | 英语 |
国家 | France ; USA |
收录类别 | SCI-E |
WOS记录号 | WOS:000329766200030 |
WOS关键词 | WEST-AFRICAN COLONIES ; AVHRR-NDVI DATA ; VEGETATION DYNAMICS ; HAPEX-SAHEL ; SEMIARID ENVIRONMENT ; SAHARA DESERT ; DATA SETS ; DESERTIFICATION ; MODIS ; TRENDS |
WOS类目 | Environmental Sciences ; Remote Sensing ; Imaging Science & Photographic Technology |
WOS研究方向 | Environmental Sciences & Ecology ; Remote Sensing ; Imaging Science & Photographic Technology |
资源类型 | 期刊论文 |
条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/184708 |
作者单位 | 1.Observ Midi Pyrenees, UMR CNRS UPS IRD CNES 5563, F-31400 Toulouse, France; 2.NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA |
推荐引用方式 GB/T 7714 | Dardel, C.,Kergoat, L.,Hiernaux, P.,et al. Re-greening Sahel: 30 years of remote sensing data and field observations (Mali, Niger)[J],2014,140:350-364. |
APA | Dardel, C.,Kergoat, L.,Hiernaux, P.,Mougin, E.,Grippa, M.,&Tucker, C. J..(2014).Re-greening Sahel: 30 years of remote sensing data and field observations (Mali, Niger).REMOTE SENSING OF ENVIRONMENT,140,350-364. |
MLA | Dardel, C.,et al."Re-greening Sahel: 30 years of remote sensing data and field observations (Mali, Niger)".REMOTE SENSING OF ENVIRONMENT 140(2014):350-364. |
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