The objective of this study is to better understand the complexity of deforestation processes in southern Cameroon by testing a multivariate, spatial model of land-cover change trajectories associated with deforestation. The spatial model integrates a spectrum of independent variables that characterize land rent on a spatially explicit basis. The use of a time series of high-spatialresolution remote sensing images (Landsat MSS and SPOT XS), spanning two decades, allows a thorough validation of spatial projections of future deforestation. Remote sensing observations reveal a continuous trend of forest clearing and forest degradation in southern regions of Cameroon, but with a highly fluctuating rate. A significant proportion of the areas subject to a landcover conversion experienced other changes in the following years. The study also demonstrates that modeling land-cover change trajectories over several observation years allows a better projection of areas with a high probability of change in land-cover than projecting such areas on the basis of observations from the previous time period alone. Statistical results suggest that, in our southern Cameroon study area, roads mostly increased the accessibility of the forest for migrants rather than providing incentives for a transformation of local subsistence agriculture into marketoriented farming systems. The spatial model developed in this study allows simulations of likely impacts of human actions, leading to a transformation of the landscape (e.g., road projects) on key landscape attributes (e.g., biodiversity). Currently, several road projects or major logging concessions exist in southern Cameroon. Key Words: deforestation, land-use change, Africa, geographic information systems, landscape model. nderstanding processes of land-use and land-cover change has always been an important research area in geography. This research is receiving renewed interest thanks to a combination of new demands for understanding anthropogenic surface processes (Meyer and Turner 1994) and the maturation of technologies used to collect and analyze large amounts of spatially explicit data on the land surface (Lambin 1997). Enhanced monitoring and modeling abilities allow researchers to improve the detailed spatial modeling of land-use and land-cover changes while still achieving the level of generality that is required for a global perspective on such changes.Land-cover changes are often conceived as simple and irreversible conversions from one cover type to another. In this idealized representation, deforestation would be a total and permanent change from a dense forest landscape to an area with a low tree cover, and agricultural expansion would mean the transition to permanent cultivation. While such neat schemes would make the monitoring and modeling of landcover changes a straightforward task, reality is more complex. Land-cover changes are most often noncontinuous in space, leading to complex landscape mosaics and mixtures of cover types. They are also reversible, and often fol...

Fjeldså, J., Lambin, E, and Mertens, B. 1999, Correlation between endemism and local ecoclimatic stability documented by comparing Andean bird distributions and remotely sensed land surface data. ‐ Ecography 22: 63‐78. Relationships between large‐scale patterns of biodiversity and ecoclimatic variability were examined using distributions of 789 Andean birds, recorded in 15’x 15’grid cells, and interannual differences in Normalized Difference Vegetation Index and Brightness Surface Temperature, calculated month by month and resampled to 15’cells. Following the east Andean treeline from 1°N to 18°S, there is no evidence of a latitudinal gradient in species richness, but a considerable local variation reflecting the habitat complexity in individual cells. The mean endemism (inverse range‐size for all species present in a given cell) shows well marked peaks. Pairwise comparisons of‘peaks’and adjacent‘lows’of endemism provide strong evidence for linking peaks of endemism with local ecoclimatic stability. The most important single factor responsible for this correlation could be orographic moderation of the impacts a south polar winds. Presently manifested as occasional winter freezes in the southern part of the tropical zone, these winds may have been a major determinant of vegetational changes during Pleistocene glacial periods. The correlations suggest that most endemics are relict populations which survived periods of global climatic change in places where these impacts were moderated. It is suggested that, by retaining relict populations, these places play a significant role in the recruitment to the regional species pool. The stable places were also centres of Andean cultures and have dense human populations. The current conservation strategy of reserving areas with few people therefore needs to be supplemented with actions to secure sustainable landuse in certain densely populated areas.

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The rate of forest cover loss in the humid tropics of Cameroon is one of the highest in Central Africa. The aim of the large-scale, two-year research project described here was to understand the effect of the country's economic crisis and policy change on small-scale agricultural systems and land-clearing practices. Hypotheses were tested through surveys of more than 5000 households in 125 villages, and through time-series remote sensing analysis at two sites. The principal findings are that: (1) the rate of deforestation increased significantly in the decade after the 1986 onset of the crisis, as compared to the decade prior to the crisis; (2) the main proximate causes of this change were sudden rural population growth and a shift from production of cocoa and coffee to plantain and other food crops; and (3) the main underlying causes were macroeconomic shocks and structural adjustment policies that led to rural population growth and farming system changes. The implication of this study is that it is necessary to understand and anticipate the undesirable consequences of macroeconomic shocks and adjustment policies for forest cover. Such policies, even though they are often not formulated with natural resource consequences in mind, are often of greater relevance to the fate of forests than forest policy.