Tropical forest transitions: structural changes in forest area, composition and landscape

Most studies on tropical forest dynamics focus on the processes of deforestation and forest degradation and its associated ecological impacts; comparatively little attention is given to the emergence of forest transitions. This review gives an overview of forest transitions in the tropics as involving a structural reversal from a decreasing to expanding forest area as well as related changes in forest quality and forest landscape. After introducing the concept of forest transition it first summarizes the changing forest area in tropical countries. It then discusses how the identification of a forest transition greatly depends on how forests are defined. Three types of forests with contrasting forest composition are distinguished, i.e. natural forests, modified forests and transformed forests, and forest transitions are characterized as involving either forest conversion or forest restoration. Next, forest transitions are related to changes in forested landscapes and described as involving either forest extension at a retracting agricultural frontier or incorporation of forests in forested mosaic landscapes. These processes are driven by either macro-scale socio-ecological feedbacks or socio-economic changes or by location-specific development of rural forests as part of farming intensification. This paper concludes that forest transitions do not just involve a return of natural forests and/or extension of forest plantations on forest lands, but also a multidimensional co-evolution in social and ecological conditions involving an increasing incorporation of socialized forests in forested landscapes