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" Dynamics of biodiversity and human carrying capacity in the Senegal Sahel "
P. J. Gonzalez
J. P. Holdren
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Latin Dissertation
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English
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| Record Number
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1113061
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| Doc. No
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TLpq304347116
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| Main Entry
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J. P. Holdren
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P. J. Gonzalez
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| Title & Author
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Dynamics of biodiversity and human carrying capacity in the Senegal Sahel\ P. J. GonzalezJ. P. Holdren
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| College
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University of California, Berkeley
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| Date
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1997
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| student score
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1997
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| Degree
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Ph.D.
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| Page No
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427
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| Abstract
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Extensive field surveys over 7600 km2 in Northwest Senegal and analyses of ecological and socio-economic data show that biodiversity and tree densities have declined in the last half of the 20usd\rm\sp{th}usd Century, that population densities have risen above carrying capacity, and that the natural regeneration of local species would most effectively augment the land's ability to support people and lead towards sustainability. Species richness of areas of 400 ha declined from 64 2 species ca.1945 to 43 2 in 1993, an extremely significant usd\rm(p<0.001)usd decrease. Densities of trees of usd\rm h\ge3usd m decreased from 10.1 0.3 trees ha in 1954 to usd7.8\pm0.3usd trees ha in 1989, also extremely significant usd\rm(p Arid Sahel species have expanded from the North, tracking a concomitant retraction of mesic Sudan and Guinean species to the South. Vegetation zones have shifted at a rate of 500-600 m y Correlations coefficients, t-tests, scANOVA, gradient analyses, principal components analyses, and canonical correlations analyses mark latitude and longitude, proxies for rainfall and temperature, as the most significant factors determining tree and shrub distribution. The rural population of 45 people km exceeded the 1993 carrying capacity of firewood from shrubs of 13 people km (range 1-21 people km Charcoal use also exceeded trunk wood production. Standing wood biomass fell 2100 kg ha from 1956 to 1993, releasing CO2 at a rate of 60 kg C personusd\rm\sp{-1}y\sp{-1}.usd Seventy-seven percent of local people favor natural regeneration of local species over the plantation of exotic species. Natural regeneration is practiced traditionally, requires no special inputs, and encourages the propagation of multiple-use trees. This research has produced the first documentation of a large-scale decline in species richness and tree densities in the West African Sahel, the first range maps of all 126 tree and shrub species in the Senegal Sahel, the first complete and accurate list of the Wolof names of the 126 species, and the first large-scale carrying capacity analysis in the Sahel based on field data. The research provides a practical plan for sustainable natural resource management for international development organizations in the field. This could help improve the life of the Senegalese villager, for whom the work is ultimately destined.
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Biological sciences
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Ecology
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firewood
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forestry
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Health and environmental sciences
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sustainable development
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