Abstract
This study was carried out in the classified forest of Djoli-Kera found in the South-Eastern part of Chad. It aimed to analyze the spatial and temporal dy-namics of land cover between 1972 and 2013 and to determine the drivers of vegetation degradation. The databases used were made up of 4 Landsat satellite images (1MSS of 1972, 5TM of 1984, 7ETM+ of 1990 and 2010) and a spot 6 image of 2013, supplemented by field studies. Satellite images were processed using ENVI and ArcGIS software. Interview was used to identify the activities carried out by the local population. In 1972, the classified forest consisted of four types of land cover, the most important of which was open forest (51%), followed by wooded savannah (26%), tree savannah (21%) and sparse vegetation consisting of farms and fallows (2%). Gradually open forest and tree savannah disappeared. In 2013, the main types of land cover were shrub savannah (40%), sparse vegetation (28%), wooded savannah (12%), bare soil (12%) and dwellings (8%). Livestock, agriculture, wood collection and bushfires are perceived by local population as main drivers of forest cover change. Awareness-raising, monitoring and regulation of access to resources must be pursued, but also managers of the classified forest must accompany the local populations in the planting of trees and the setting up of more efficient farming systems to reduce pressure on the forest’s resources.
Highlights
Tropical forests are one of the terrestrial ecosystems richest in biodiversity
In 1972, the classified forest consisted of four types of land cover, the most important of which was open forest (51%), followed by wooded savannah (26%), tree savannah (21%) and sparse vegetation consisting of farms and fallows (2%)
Analysis of satellite images (Figures 2-6) revealed that in 1972 the Djoli-Kera forest had only four types of land cover. These land cover have evolved in size and physiognomy over the years, either by disappearing completely or by losing surface area to give way to other land cover types
Summary
Tropical forests are one of the terrestrial ecosystems richest in biodiversity. They offer many forms of habitat for plant, animal and micro-organism species and livelihoods for those living or residing nearby. Tropical forests spread over an area of 1376 million km, representing 60% of the world’s forests (FAO, 2010) and play a key role in the carbon cycle at both flux and volume levels. They are major challenge for biodiversity conservation, water purification and climate change mitigation (Le Guen, 2010). FAO (2016) reported a net annual loss of forest of about 7 million hectares between 2000 and 2010 and increase of agricultural land of 6 million hectare per year in tropical countries. Degradation, deforestation and land uses change in developing countries would contribute for about 20 per cent of the annual global greenhouse gas emissions (Le Guen, 2010). Remote sensing has proven to be an essential technology for determining land cover at different scales (Loveland & Dwyer, 2012; Hansen et al, 2013)
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