Impacts of community-forest management on land use change, vegetation dynamics and carbon stocks in South-Eastern Senegal
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Date
April, 2016
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Abstract
Forest management is considered as a strategy of mitigation and adaptation to climate change
because of its ability to contribute to improve local livelihood and reduce carbon emission from
forest. This study investigated the impacts of community-forest management on changes in land
use and land cover, vegetation composition and structure as well as carbon stocks in Missirah
Forest located in south-eastern Senegal. Land use and land cover change was mapped using
Landsat images of 1990, 2003, and 2014 combined with ground truth data. The direction, rate of
change and transition among land use and land cover types were determined. Forest inventory
was conducted by sampling randomly from a number of permanent sampling plots. Data was
collected from 94 circular plots of 1256m2 in elevated lands and 57 rectangular plots of 400m2 in
riparian forest. Biomass data was collected using destructive sampling and carbon stocks
estimated by means of a model. Socio-economic data on drivers of deforestation and forest
degradation was collected through a structured survey among 136 selected households in five
villages using multi-stage sampling. The results of the land use and land cover revealed six
classes: riparian forest, tree savanna, shrub savanna, degraded shrub savanna, croplands and
settlements. Vegetation types decreased in all periods with the exception of shrub savanna that
experienced an increase of 1.46 % between 1990 and 2003. The entire forest cover showed a
decrease of 9.08 % between 1990 and 2003 and 13.63 % from 2003 to 2014. Croplands
experienced a continual increase with a rate of more than 100% from 1990 to 2003. The
transition to less wooded vegetation (31.58 %) was higher than transition to more wooded
vegetation (13.91 %). Analysis of Variance (ANOVA) showed a significant difference between
species richness in 2002 and 2013 (p-value = 0.0003) which were 50 and 42 respectively.
Prescribed species for charcoal production experienced the highest decline in their Importance
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Value Index (IVI). The mixed model ANOVA applied on structural parameters revealed that
parameters showed a significant decline with the exception of stem density suggesting the forest
was not recovering from harvests. The average carbon density of the forest was estimated at
34.10 Mg C ha-1. It varied from 71.87 Mg C ha-1in riparian forest to 12.73 Mg C ha-1 in tree
savanna and 11.42 Mg C ha-1in shrub savanna. Most of the carbon stock (67 %) was found in
five out of the fifty four species. The decreases in forest cover from1990 to 2014 resulted in a
loss of 24.43 % of total carbon stocks. Local perceptions indicate a general decline in vegetation
quality. Age group and location of communities significantly affected the rating of the level of
degradation. Species cited as declining in numbers were those of high economic value and the
perceptions were consistent with results of the inventory. The perceived drivers of vegetation
degradation were charcoal production, bush fire, seasonal migration of cattle and illegal logging.
Main economic activities and location of communities significantly affected the ranking of the
perceived drivers. This study revealed that the conditions under which forest are managed
currently do not constitute a sustainable response to deforestation and degradation induced by
charcoal production.
Description
A Thesis submitted to the Department of Civil Engineering, College of
Engineering, Kwame Nkrumah University of Science and Technology in partial
fulfilment of the requirements for the degree of Doctor of Philosophy in Climate Change and Land Use,