NDVI-Derived Vegetation Trends and Driving Factors in West African Sudanian Savanna — Oak Academic Publishing
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NDVI-Derived Vegetation Trends and Driving Factors in West African Sudanian Savanna
Department of Geography, Université Joseph KI-ZERBO, Ouagadougou, Burkina Faso
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Département des Eaux, Forêts et Environnement, Institut des Sciences de l’Environnement et du Développement Rural, Université de Dédougou, Dédougou, Burkina Faso
1 Department of Geography, Université Joseph KI-ZERBO, Ouagadougou, Burkina Faso
2 Département des Eaux, Forêts et Environnement, Institut des Sciences de l’Environnement et du Développement Rural, Université de Dédougou, Dédougou, Burkina Faso
The Sudanian savanna is a key vegetation biome in West Africa providing food and vital ecosystem services. Recently, it has been reported alarming vegetation loss in this biome, calling for more investigation, relevant to tackle land degradation and ensure food security. However, vegetation dynamics in this area remains a matter of debate, and one of the main challenges is to document consistently the underlying driving factors. This study aimed at assessing vegetation trends and driving factors from 2000 to 2022. NDVI trend, detected using the Mann-Kendall’s monotonic trend test, was used as proxy to express vegetation dynamics. In addition to the non-parametric Spearman correlation analysis, variables importance scores, derived from Random Forest (RF) classifications, were used to determine key driving factors among climatic, topographic, edaphic, accessibility and demographic factors. During 2000-2022, no significant trends largely characterised the vegetation cover of the study area. However, patterns of strong (weak) browning and strong (weak) greening affected 7.1% (10.6%) and 12.8% (19.1%) of the study area respectively. According to the driving factors analysis, the observed vegetation trends were mainly driven by rainfall dynamics (trend and mean annual), population growth and anthropogenic activities. The results of this study can support the development of efficient strategies for safeguarding vegetation cover in the Sudanian savanna of Burkina Faso.
KeywordsVegetation TrendsNDVISudanian SavannaBurkina FasoWest Africa
Stavi, I. and Lal, R. (2015) Achieving Zero Net Land Degradation: Challenges and Opportunities. Journal of Arid Environments, 112, 44-51. https://doi.org/10.1016/j.jaridenv.2014.01.016
Peng, J., Li, Y., Tian, L., Liu, Y. and Wang, Y. (2015) Vegetation Dynamics and Associated Driving Forces in Eastern China during 1999-2008. Remote Sensing, 7, 13641-13663. https://doi.org/10.3390/rs71013641
Liu, Z., Wimberly, M.C. and Dwomoh, F.K. (2016) Vegetation Dynamics in the Upper Guinean Forest Region of West Africa from 2001 to 2015. Remote Sensing, 9, 5. https://doi.org/10.3390/rs9010005
Kaptué, A.T., Prihodko, L. and Hanan, N.P. (2015) On Regreening and Degradation in Sahelian Watersheds. Proceedings of the National Academy of Sciences, 112, 12133-12138. https://doi.org/10.1073/pnas.1509645112
Li, Z., Li, X., Weia, D., Xub, X. and Wanga, H. (2010) An Assessment of Correlation on MODIS-NDVI and EVI with Natural Vegetation Coverage in Northern Hebei Province, China. Procedia Environmental Sciences, 2, 964-969. https://doi.org/10.1016/j.proenv.2010.10.108
Ribeiro, N.S., Matos, C.N., Moura, I.R., Washington-Allen, R.A. and Ribeiro, A.I. (2013) Monitoring Vegetation Dynamics and Carbon Stock Density in Miombo Woodlands. Carbon Balance and Management, 8, Article No. 11. https://doi.org/10.1186/1750-0680-8-11
Bouvet, A., Mermoz, S., Le Toan, T., Villard, L., Mathieu, R., Naidoo, L. and Asner, G.P. (2018) An Above-Ground Biomass Map of African Savannahs and Woodlands at 25 m Resolution Derived from ALOS PALSAR. Remote Sensing of Environment, 206, 156-173. https://doi.org/10.1016/j.rse.2017.12.030
Braimoh, A.K. (2004) Seasonal Migration and Land-Use Change in Ghana. Land Degradation and Development, 15, 37-47. https://doi.org/10.1002/ldr.588
Hobbs, R.J. (1990) Remote Sensing of Spatial and Temporal Dynamics of Vegetation. Ecological Studies, 79, 203-219. https://doi.org/10.1007/978-1-4612-3302-2_10
Traore, S.S., Landmann, T., Forkuo, E.K. and Traore, P.C.S. (2014) Assessing Long-Term Trends in Vegetation Productivity Change over the Bani River Basin in Mali (West Africa). Journal of Geography and Earth Sciences, 2, 21-34. https://doi.org/10.15640/jges.v2n2a2
Fensholt, R. and Sandholt, I. (2005) Evaluation of MODIS and NOAA AVHRR Vegetation Indices with in Situ Measurements in a Semi-Arid Environment. International Journal of Remote Sensing, 26, 2561-2594. https://doi.org/10.1080/01431160500033724
Anyamba, A. and Tucker, C.J. (2005) Analysis of Sahelian Vegetation Dynamics Using NOAA-AVHRR NDVI Data from 1981-2003. Journal of Arid Environments, 63, 596-614. https://doi.org/10.1016/j.jaridenv.2005.03.007
Olsson, L., Eklundh, L. and Ardo, J. (2005) A Recent Greening of the Sahel— Trends, Patterns and Potential Causes. Journal of Arid Environments, 63, 556-566. https://doi.org/10.1016/j.jaridenv.2005.03.008
Mbow, C., Brandt, M., Ouedraogo, I., de Leeuw, J. and Marshall, M. (2015) What Four Decades of Earth Observation Tell Us about Land Degradation in the Sahel? Remote Sensing, 7, 4048-4067. https://doi.org/10.3390/rs70404048
Knauer, K., Gessner, U., Dech, S. and Kuenzer, C. (2014) Remote Sensing of Vegetation Dynamics in West Africa. International Journal of Remote Sensing, 35, 6357-6396. https://doi.org/10.1080/01431161.2014.954062
Leroux, L., Bégué, A. and Lo, S.D. (2014) Regional Analysis of Crop and Natural Vegetation in West Africa Based on NDVI Metrics. International Geoscience and Remote Sensing Symposium (IGARSS), Quebec City, 13-18 July 2014, 5107-5110.
Rasmussen, K., Fensholt, R., Fog, B., Rasmussen, L.V. and Yanogo, I. (2014) Explaining NDVI Trends in Northern Burkina Faso. Journal of Geography, 114, 17-24. https://doi.org/10.1080/00167223.2014.890522
Leroux, L., Bégué, A., Seen, D.L., Jolivot, A. and Kayitakire, F. (2017) Driving Forces of Recent Vegetation Changes in the Sahel: Lessons Learned from Regional and Local Level Analyses. Remote Sensing of Environment, 191, 38-54. https://doi.org/10.1016/j.rse.2017.01.014
Zoungrana, B.J.-B., Conrad, C., Thiel, M., Amekudzi, L.K. and Da, E.D. (2018) MODIS NDVI Trends and Fractional Land Cover Change for Improved Assessments of Vegetation Degradation in Burkina Faso, West Africa. Journal of Arid Environments, 153, 66-75. https://doi.org/10.1016/j.jaridenv.2018.01.005
Braimoh, A.K. and Vlek, P.L.G. (2005) Land-Cover Change Trajectories in Northern Ghana. Environmental Management, 36, 356-373. https://doi.org/10.1007/s00267-004-0283-7
Dimobe, K., Ouédraogo, A., Soma, S., Goetze, D., Porembski, S. and Thiombiano, A. (2015) Identification of Driving Factors of Land Degradation and Deforestation in the Wildlife Reserve of Bontioli (Burkina Faso, West Africa). Global Ecology and Conservation, 4, 559-571. https://doi.org/10.1016/j.gecco.2015.10.006
Ghimire, B., Rogan, J., Rodríguez-Galiano, V., Panday, P. and Neeti, N. (2012) An Evaluation of Bagging, Boosting, and Random Forests for Land-Cover Classification in Cape Cod, Massachusetts, USA. GIScience & Remote Sensing, 49, 623-643. https://doi.org/10.2747/1548-1603.49.5.623
Maxwell, A.E., Warner, T.A. and Fang, F. (2018) Implementation of Machine-Learning Classification in Remote Sensing: An Applied Review. International Journal of Remote Sensing, 39, 2784-2817. https://doi.org/10.1080/01431161.2018.1433343
Ali, I., Greifeneder, F., Stamenkovic, J., Neumann, M. and Notarnicola, C. (2015) Review of Machine Learning Approaches for Biomass and Soil Moisture Retrievals from Remote Sensing Data. Remote Sensing, 7, 16398-16421. https://doi.org/10.3390/rs71215841
Thanh Noi, P. and Kappas, M. (2017) Comparison of Random Forest, K-Nearest Neighbor, and Support Vector Machine Classifiers for Land Cover Classification Using Sentinel-2 Imagery. Sensors, 18, Article No. 18. https://doi.org/10.3390/s18010018
Löw, F., Knöfel, P. and Conrad, C. (2015) Analysis of Uncertainty in Multi-Temporal Object-Based Classification. ISPRS Journal of Photogrammetry and Remote Sensing, 105, 91-106. https://doi.org/10.1016/j.isprsjprs.2015.03.004
Fontès, J. and Guinko, S. (1995) Vegetation Map and Land Use in Burkina Faso. Explanatory Note: French Ministry of Cooperation.
Zoungrana, B.J.-B., Conrad, C., Amekudzi, L.K., Thiel, M., Da, E.D., Forkuor, G. and Löw, F. (2015) Multi-Temporal Landsat Images and Ancillary Data for Land Use/Cover Change (LULCC) Detection in the Southwest of Burkina Faso, West Africa. Remote Sensing, 7, 12076-12102. https://doi.org/10.3390/rs70912076
Callo-Concha, D., Gaiser, T. and Ewert, F. (2012) Farming and Cropping Systems in the West African Sudanian Savanna. WASCAL Research Area: Northern Ghana, Southwest Burkina Faso and Northern Benin. Bonn, No. 100.
Derbile, E.K. (2010) Local Knowledge and Livelihood Sustainability under Environmental Change in Northern Ghana. PhD Dissertation, University of Bonn, Bonn, 296 p.
Zhao, S., Zhao, X., Zhao, J., Liu, N., Sun, M., Mu, B., Sun, N. and Guo, Y. (2022) Grassland Conservation Effectiveness of National Nature Reserves in Northern China. Remote Sensing, 14, Article No. 1760. https://doi.org/10.3390/rs14071760
Najafi, Z., Fatehi, P. and Darvishsefat, A.A. (2019) Vegetation Dynamics Trend Using Satellite Time Series Imagery. The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 42, 783-788. https://doi.org/10.5194/isprs-archives-XLII-4-W18-783-2019
Li, Y., Xie, Z., Qin, Y. and Zheng, Z. (2019) Estimating Relations of Vegetation, Climate Change, and Human Activity: A Case Study in the 400 mm Annual Precipitation Fluctuation Zone, China. Remote Sensing, 11, Article No. 1159. https://doi.org/10.3390/rs11101159
Forkuor, G., Hounkpatin, O.K., Welp, G. and Thiel, M. (2017) High Resolution Mapping of Soil Properties Using Remote Sensing Variables in South-Western Burkina Faso: A Comparison of Machine Learning and Multiple Linear Regression Models. PLOS ONE, 12, e0170478. https://doi.org/10.1371/journal.pone.0170478
Breiman, L. (2001) Random Forests. Machine Learning, 45, 5-32. https://doi.org/10.1023/A:1010933404324
Kuhn, M. (2008) Building Predictive Models in R Using the Caret Package. Journal of Statistical Software, 28, 1-26. https://doi.org/10.18637/jss.v028.i05
Strobl, C., Boulesteix, A.L., Zeileis, A. and Hothorn, T. (2007) Bias in Random Forest Variable Importance Measures: Illustrations, Sources and a Solution. BMC Bioinformatics, 8, 8-25. https://doi.org/10.1186/1471-2105-8-25
Lucio, P.S., Molion, L.C.B., Valadão, C.E.A., Conde, F.C., Ramos, A.M. and de Melo, M.L.D. (2012) Dynamical Outlines of the Rainfall Variability and the ITCZ Role over the West Sahel. Atmospheric and Climate Sciences, 2, 337-350. https://doi.org/10.4236/acs.2012.23030
Bognounou, F., Tigabu, M., Savadogo, P., Thiombiano, A., Boussim, I.J., Oden, P.C. and Guinko, S. (2010) Regeneration of Five Combretaceae Species along a Latitudinal Gradient in Sahelo-Sudanian Savanna of Burkina Faso. Annals of Forest Science, 67, 306. https://doi.org/10.1051/forest/2009119
Herrmann, S.M., Anyamba, A. and Tucker, C.J. (2005) Recent Trends in Vegetation Dynamics in the African Sahel and Their Relationship to Climate. Global Environmental Change, 15, 394-404. https://doi.org/10.1016/j.gloenvcha.2005.08.004
Gray, C.L. (2005) What Kind of Intensification? Agricultural Practice, Soil Fertility and Socioeconomic Differentiation in Rural Burkina Faso. The Geographical Journal, 171, 70-82. https://doi.org/10.1111/j.1475-4959.2005.00150.x
Knauer, K., Gessner, U., Fensholt, R., Forkuor, G. and Kuenzer, C. (2017) Monitoring Agricultural Expansion in Burkina Faso over 14 Years with 30 m Resolution Time Series: The Role of Population Growth and Implications for the Environment. Remote Sensing, 9, Article No. 132. https://doi.org/10.3390/rs9020132
Houessou, L.G., Teka, O., Imorou, I.T., Lykke, A.M. and Sinsin, B. (2013) Land Use and Land-Cover Change at “W” Biosphere Reserve and Its Surroundings Areas in Benin Republic (West Africa). Environment and Natural Resources Research, 3, 87-101. https://doi.org/10.5539/enrr.v3n2p87
Ouedraogo, I., Tigabu, M., Savadogo, P., Compaore, H., Oden, P.C. and Ouadba, J.M. (2010) Land Cover Change and Its Relation with Population Dynamics in Burkina Faso, West Africa. Land Degradation and Development, 21, 453-462. https://doi.org/10.1002/ldr.981
Gessner, U., Machwitz, M., Conrad, C. and Dech, S. (2013) Estimating the Fractional Cover of Growth Forms and Bare Surface in Savannas. A Multi-Resolution Approach Based on Regression Tree Ensembles. Remote Sensing of Environment, 129, 90-102. https://doi.org/10.1016/j.rse.2012.10.026
Gessner, U., Machwitz, M., Esch, T., Tillack, A., Naeimi, V., Kuenzer, C. and Dech, S. (2015) Multi-Sensor Mapping of West African Land Cover Using MODIS, ASAR and TanDEM-X/TerraSAR-X Data. Remote Sensing of Environment, 164, 282-297. https://doi.org/10.1016/j.rse.2015.03.029
Forkuor, G. (2014) Agricultural Land Use Mapping in West Africa Using Multi-Sensor. PhD Dissertation, Julius-Maximilians-Universität, Würzburg, 175 p.
Krakauer, N., Lakhankar, T. and Anadón, J. (2017) Mapping and Attributing Normalized Difference Vegetation Index Trends for Nepal. Remote Sensing, 9, Article No. 986. https://doi.org/10.3390/rs9100986