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Desertification or Greening?
Beginning in the late 1960s, the West African Sahel zone has repeatedly made headlines for a number of – potentially related – environmental and economic problems, which manifest themselves in changes in land cover. These changes are often referred to as ‘desertification’, despite a lack of consensus among scientists over the exact meaning of this notion, the mechanisms governing it, and the extent of the problem in the Sahel. Recent remote sensing-based studies have shown an overall greening trend in parts of the Sahel, which might indicate that positive developments have been going on. However, the meaning of ‘greening’ is as vague as that of ‘desertification’, and its implications on the ground are far from clear and unambiguous
The overall goal of this project is to develop empirical evidence that can inform our understanding of the interactions among land use, land cover, and people’s livelihoods in the in the face of rainfall variability and unpredictability in two Sahelian countries, Mauritania and Senegal. We will:
(1) use remote sensing techniques to measure land cover changes and map land use,
(2) conduct field surveys to reconstruct land use and management practices employed by natural resource user groups
(3) use information on land use decision-making by user groups with observed changes in land cover to develop a spatially explicit agent-based model that can be used to simulate land cover change under different climatic and management scenarios.
The proposed project will contribute to the understanding of the relative contribution to land use/land cover change of human behavior and climate variability in marginal climatic environments. While the issue of desertification has so far been mostly approached from either the natural or the social science perspective, this project's integrated approach will help advance the frontiers of understanding across disciplines and generate new thought and discussion. The study results may also help break the gridlock in the desertification debate. Furthermore, the synergistic effects produced from combining local wisdom and experience in dealing with climatic uncertainty with scientific expertise in remote sensing and spatial modeling will contribute to a deepened understanding of the driving forces influencing desertification and greening. Ideally, with the help of sampling, analysis and modeling protocols developed and validated in the proposed project, future research could be expanded to several more sites to embrace the large diversity of relations between environment and livelihood systems found across the Sahel – a precondition for refining hypotheses and building theories.
The broader impacts of the project involve K-12 education in the US, community outreach in Africa, as well as strengthening international institutional ties. Starting in year one, we will construct a poster board exhibit on desertification and build it up in the following years based on our findings from the Sahel. It will be housed in the Anthropology Building lobby at U of A during the project, as well as used for school presentations and visiting K-12 tours of the anthro museum. In communicating our research results to the public, we will also make use of the outreach model developed at the Center for Capacity Building at NCAR (http://www.ccb.ucar.edu/). By the end of project, we plan to organize and convene a "usable science" workshop, in which we share the outcome of our research with community representatives and educators in our study region, so as to inform natural resource managers. The project will further develop the cooperative linkages between the University of Arizona, the University of Nouakchott and the Centre de Suivi Ecologique in Dakar, Senegal and increase cooperation between the University of Arizona, NCAR and the USGS. The project will result in a database and scientific infrastructure that can be used in a decision-support system across the Sahel and will thereby contribute to bridging the gap between methodological research and operational implementation.
Stefanie Herrmann, Office of Arid Land Studies University of Arizona & Center for Capacity Building National Center for Atmospheric Research Boulder, CO
Mamadou A. Baro, Bureau of Applied Research in Anthropology, University of Arizona
Randy Gimblett, School of Natural Resources and the Environment, University of Arizona
Thomas K. Park, Department of Anthropology University of Arizona
Funded by: National Science Foundation - BCS - Geography and Regional Science
Herrman, S. M., Anyamba, A., Tucker, C.J. . 2005. Recent Trends in Vegetation Dynamics in the African Sahek and their Relationship to Climate. Global Environmental Change 15, 394-404.
Two Landsat images of the Foum Gleita region - site of an irrigation project
that was put in in 1986 and has contributed to the greening in the
region. As we learned, the kind of greening we observe on satellite imagery is
not the desired greening: a lot of the irrigation scheme has fallen into
disrepair, fields have been abandoned and taken over by shrubs. Certainly
greener today, but inadvertently so.
Cover Image: Researchers discuss a satellite image with villagers in Bakhat Dakla, Mauritania, showing their village and surroundings. Observations from space show that the area they live in appears to have gotten greener in the past 30 years.
Above: This photo shows the effects of diguettes (small earthen dykes): they slow
down surface runoff and increase infiltration and decrease soil loss by
erosion, which helps vegetation growth. Diguettes are constructed by the
population as a management tool to improve agricultural land and pastures.