Fabing, Aline 
  
Thus, the consequence of the demographic explosion (C.NS.E.E, 1980, 1988; D.S.D.S., 1989; I.N.S.E.E., 1961) and the 
rural exodus, throughout disproportionate migration flows, is an urban concentration, which has environmental effects. 
These repercussions are the following: 
Increase of human pressure on the rurban fringe of about 100-km (Fabing in redaction). In these areas forests are 
frequently replaced by degraded formations, which have no time to develop into a secondary forest stage. This depends 
on many factors: shifting cultivation (reduced fallow time), fuel wood (firewood and charcoal exploitation to supply the 
Pointe-Noire agglomeration. Even along the road network, the human settlements and the associated agricultural 
extension impose constraints on the forest resource (degradation in a belt of 5 to 10 km around the villages.). 
On the other hand, areas that are far away from the agglomeration became human deserts in which forest transgression 
is possible while only bush fire stops this expansion. Logging has an inconsequential effect on the forest degradation in 
the case where there is no agricultural continuum. 
1.3 Objectives 
In this context, we defined different objectives in order to develop the adequate procedure to improve the decision 
support for sustainable development. These objectives are the following. 
First, to establish a spatial assessment of the antagonism between natural forest dynamics and population pressures 
(example of the urban expansion and its consequences on the environmental resources at a regional scale) through 
remote sensing treatment, GIS analysis and interpretation. 
Second, to identify and quantify the effects of human organisation and activities on the forest resources through field 
researches and remote sensing analysis. 
Third, to provide a reliable support for natural resources management by maps predicting deforestation risks via 
dynamic predictive modelling. 
Fourth, to take into account political and individual solutions concerning the forest degradation problem. 
MATERIAL AND METHODS 
1.4 Material 
To meet these objectives, and to analyse the spatial and temporal changes in landscape patterns, photogrammetric and 
remote sensing data were used. 
1.4.4 Data choice. 
The aerial photographs have been chosen since they are the only data that exist and, give information fifty years ago. 
The resolution is about 5 meters. For the SAR data, the potential and capability for mapping and monitoring natural 
resources is already widely known, particularly in the persistent cloud-covered humid tropic region like Congo. JERS-1 
data may provide appropriate metrics (pixel of 12.50 meters) for a meso-scale study and the L-band data are useful for 
regional vegetation changes and as an information source for tropical environment monitoring. We have three multi- 
date images from one area. The study concerns restricted zones appropriate for the understanding of most typical cases 
(figure 1). 
The ground work has been defined on socio-economic inquiries (fuel wood consumption, agricultural practise, 
environmental perception) and, physical inquiries like carbon 13 sampling along 100 meters transects for each case 
complemented with botanical investigations. Also this work was supplied with bibliographical researches (literatures 
and administrative documentation). 
1.5 Methods 
Two methods were used: descriptive methods, which may allow to assess accurately past change (1951-1996) but are 
dependant on the availability of recent data or information, and predictive method, which may use historical data to 
estimate past and present changes when recent data are not available, as well as future change, through the use of 
  
422 International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000.