Vegetation impoverishment despite greening: A case study from central Senegal

Herrmann, Stefanie M.; Tappan, G. Gray

doi:10.1016/j.jaridenv.2012.10.020

Cited by 123 publications

(118 citation statements)

References 35 publications

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“…Although our results point to the important role of postdrought tree population recovery and, in some areas, active tree planting in the regreening of the Sahel, such changes in tree cover may be associated with changes in tree species diversity not detected in our remote sensing data (28,29,51,52). Higher primary production is not necessarily associated with a higher biodiversity and the decline in populations of economically and culturally important trees and shrubs-despite the increase in woody cover-may explain the negative perception of vegetation condition among some local populations (51,52).…”

Section: Trend Assessments Using Changes In Decadal and Interannual Rmentioning

confidence: 61%

“…The existence and nature of Sahelian regreening following the 1980s drought has been greatly debated, with considerable polarization between camps arguing the desertification and recovery narratives (20)(21)(22)(25)(26)(27)(28)(29). A few studies have examined the specific role of long-term changes in woody and herbaceous components (e.g., refs.…”

Section: Trend Assessments Using Changes In Decadal and Interannual Rmentioning

confidence: 99%

“…Independent studies have also documented farmer strategies to restore landscape-scale function, in particular through planting of trees and soil conservation actions (23,24). Other authors, however, have used both satellite and field data to argue that the apparent "regreening" of the Sahel may still hide real degradation in the form of ecosystem ability to use available rainfall (i.e., rain-use efficiency), or in the structure and species composition of the vegetation (25)(26)(27)(28)(29).…”

mentioning

confidence: 99%

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On regreening and degradation in Sahelian watersheds

Kaptué

Prihodko

Hanan

2015

Proc. Natl. Acad. Sci. U.S.A.

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Over many decades our understanding of the impacts of intermittent drought in water-limited environments like the West African Sahel has been influenced by a narrative of overgrazing and human-induced desertification. The desertification narrative has persisted in both scientific and popular conception, such that recent regional-scale recovery ("regreening") and local success stories (community-led conservation efforts) in the Sahel, following the severe droughts of the 1970s-1980s, are sometimes ignored. Here we report a study of watershed-scale vegetation dynamics in 260 watersheds, sampled in four regions of Senegal, Mali, and Niger from 1983-2012, using satellite-derived vegetation indices as a proxy for net primary production. In response to earlier controversy, we first examine the shape of the rainfall-net primary production relationship and how it impacts conclusions regarding greening or degradation. We conclude that the choice of functional relationship has little quantitative impact on our ability to infer greening or degradation trends. We then present an approach to analyze changes in long-term (decade-scale) average rain-use efficiency (an indicator of slowly responding vegetation structural changes) relative to changes in interannual-scale rainfall sensitivity (an indicator of landscape ability to respond rapidly to rainfall variability) to infer trends in greening/degradation of the watersheds in our sample regions. The predominance of increasing rain-use efficiency in our data supports earlier reports of a "greening" trend across the Sahel. However, there are strong regional differences in the extent and direction of change, and in the apparent role of changing woody and herbaceous components in driving those temporal trends.Sahel | desertification | rain-use efficiency | drylands | West Africa

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Section: Trend Assessments Using Changes In Decadal and Interannual Rmentioning

confidence: 61%

Section: Trend Assessments Using Changes In Decadal and Interannual Rmentioning

confidence: 99%

mentioning

confidence: 99%

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On regreening and degradation in Sahelian watersheds

Kaptué

Prihodko

Hanan

2015

Proc. Natl. Acad. Sci. U.S.A.

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“…Time series of medium and high resolution RS data have been widely used for such analyses because fine scale processes, including human influences on vegetation, can be observed (e.g., Kelder et al 2013;Rasmussen et al 2014;Ruelland et al 2008;2010;Tappan et al 2000;. Other researchers have explored hotspots of vegetation change identified by coarse resolution RS through field based surveys and interviews with local land users (e.g., Milich and Weiss 2000;Herrmann and Tappan 2013;.…”

Section: Vegetation and Environmental Factors And Vegetation Change)mentioning

confidence: 99%

Remote sensing of vegetation in the Sudano-Sahelian zone: A literature review from 1975 to 2014

Karlson

Ostwald

2016

Journal of Arid Environments

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Scarcity of in situ vegetation data inhibits research and natural resource management in the Sudano-Sahelian zone (SSZ). Satellite and aerial remote sensing (RS) constitute key technologies for improving the availability of vegetation data, and consequently the preconditions for scientific analysis and monitoring. The aim of this paper was to investigate how the hands-on application of RS for vegetation analysis has developed in the SSZ by reviewing the scientific literature published between 1975 and 2014. The paper assesses the usages and the users of RS by focusing on four aspects of the material (268 peer-reviewed articles), including publication details (time of publication, scientific discipline of journals and author nationality), geographic information (location of study areas and spatial scale of research), data usage (application of RS systems and procedures for accuracy assessments), and research topic (scientific objective of the research). Three key results were obtained: i) the application of RS to analyze vegetation in the SSZ has increased consistently since 1977 and it seems to become adopted by a growing number of scientific disciplines; ii) the contribution of African authors is low, potentially signaling a need for an increased transfer of knowledge and technology from developed countries; iii) RS has primarily been used to analyze changes in vegetation productivity and broad vegetation types, whereas its use for studying interactions between vegetation and environmental factors has been relatively low. This calls for stronger collaborative RS research that enables the mapping of additional vegetation variables of high relevance for the environmental problems facing the SSZ. Remotely sensed vegetation data are needed at spatial scales that suits the requirements of both research and natural resource management in order to further enhance the usefulness of this technology.

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“…D'un point de vue écologique, ils contribuent à l'atténuation des changements climatiques par leur capacité de séquestration du carbone (Mbow, 2009 ;Kumar et Nair, 2011) et jouent un rôle important dans la protection (Samba et al, 2012) et l'amélioration de la fertilité des sols (Samba, 2001 ;Saidou et al, 2012). Cependant, les systèmes de production agricole dans le Bassin Arachidier du Sénégal, en particulier le parc agroforestier à Cordyla pinnata (l'espèce est nommée « Dimb » en langue vernaculaire wolof ; Bergeret, 1993), sont marqués par une dégradation progressive au fil des années (Herrmann et Tappan, 2013). Les principales contraintes du parc sont les coupes pour le bois d'énergie et le bois d'oeuvre, les divers prélèvements (écorce, racine, feuilles…) de plantes médicinales, les feux de brousse et l'avancée du front pionnier agricole (Lykke, 2000).…”

Section: Introductionunclassified