Land-use influences on Sudanian landscape-scale vegetation change Burkina Faso, West Africa
Jeremy Fisher, John Mustard, Patrice Sanou (collaborator, Burkina Faso)and
Silga Ousamane (collaborator, Burkina Faso)
Burkina Faso, West Africa experiences a strong precipitation gradient
from the north (550 mm/yr) to the south (1200 mm/yr). Subsequently, Burkina
Faso straddles two major types of traditional land uses, pastoralists
(herders) in the northern desert margin and agriculturalists in south.
These groups overlap in central Burkina Faso and utilize a variety of
traditional mutually beneficial techniques to enhance fertility and maximize
herd and crop yield. Increased population growth and increased climate
variability (including longer droughts) were perceived to have pushed
a formerly sustainable practice into a driver of land degradation. With
the support of international donors and NGOs, local governments created
land management areas (LMA) to combat the loss of soil fertility, less
dense vegetation cover, and increased erosion. We hypothesize that by
observing long term (decadal) trends at carefully controlled LMAs, we
can begin to assess the various divers of change and degradation in Sudanian
West Africa.
The Nouhao Valley, Boulgou
Department of Burkina Faso, West Africa is one such LMA in SE Burkina
Faso. In the 1960s, and epidemic of Onchocerciasis (River Blindness) forced
the local populations in S. Burkina Faso to abandon river valleys, including
the Nouhao. By the early 1980s, international efforts to reduce the River
Blindness vector had succeeded in making the lands habitable again, and
the Burkinabe government quickly worked to re-settle the areas. In Nouhao,
the valley was divided into an exclusively pastoral (grazing) river valley
and an agricultural buffer, surrounded by status quo mixed use lands.
We are utilizing five Landsat scenes from 1984, 1989, 1999, 2001, and
2002 to assess sub-pixel changes in land cover (vegetation cover, eroded
surfaces, agriculture) and long time series AVHRR to provide a context
of regional and local broad vegetation changes. Evidence suggests that
since the separation of these land-use zones, vegetation in the pastoral
zone has increased significantly. This suggests that grazing pressure
and a stringent non-brush fire policy favors perennial shrubs over grasses,
leading to an increase in greenness (palatable or not) in riparian areas
and open savanna. We hypothesize that mixed land use, and seasonal low-level
burns might be critical in maintaining recognized African savanna.
The Nouhao Valley LMA is in SE Burkina Faso. The exterior, closely controlled agricultural zone surronds the river basin pastoral zone
Detail of Tenkodogo (top left), and agricultural and pastoral zones. Zones have been color enhanced for clarity
Cotton fields in the agricultural zone
Burkinabe pastoralists
Ecology and Evolutionary Biology | Environmental Change Initiative | Environmental Studies | Geological Sciences | Marine Biological Laboratory | Watson Institute
Last updated 10/20/04