Adi Mama

Forest fragmentation: causes, ecological impacts and implications for landscape management

In order to enable the development of appropriate landscape management plans, the causes and impacts of fragmentation should be fully understood. A new definition, incorporating the key aspects cited in landscape ecological literature since the 1980s, is proposed in order to shed light on the matter of fragmentation. By means of two case studies in the Democratic Republic of the Congo (Oriental Province) and in North Benin, the key role of anthropogenic activities in landscape fragmentation is evidenced; the spatial dispersion of forest vegetation is linked to population density and land use change. The potential impact of fragmentation on biodiversity is shown by an analysis of forest diversity in Ivory Coast (Tanda region), and by a study of edge effects on two rodent species in the Democratic Republic of the Congo (Kisangani). The chapter is concluded by an study on how planned corridors, assuming a spatial regrouping of existing teak plantations, could contribute to the conservation and management of remaining natural forest patches in the Atlantic Department in Benin.

A Methodological Framework to Quantify Anthropogenic Effects on Landscape Patterns

From an ecological landscape perspective, cultural landscapes can be considered as “anthropized” landscapes, in which patterns and processes are altered by human intervention. The importance of the study of spatial patterns in landscapes is justified by the pattern/process paradigm. The emergent properties of patterns reflect two components: landscape composition, which describes the number of patch types as well as their abundance, and landscape configuration, which refers to the spatial arrangement of the patch types. In this chapter, methods and strategies to analyze spatial pattern and landscape dynamics are discussed, and emphasis is put on the detection and quantification of anthropogenic effects on landscapes. Land mosaics showing anthropogenic effects are characterized by fragmented natural land cover, high frequencies of edge habitat, simple patch geometry, and dominant proportions of anthropogenic patch types. Landscape transformations associated with “anthropization” lead to a disintegration of natural patch types and to a reinforcement of anthropogenic ones. Four techniques to measure anthropogenic effects on pattern are discussed (1) the quantification of the fragmentation of natural habitats and its interpretation in terms of diversity, heterogeneity and entropy, (2) the quantification of edge effects in order to measure the ecological impact of human activity, (3) the determination of patch fractal dimensions to detect pattern simplification, and (4) the determination of the landscape transformation processes responsible for pattern dynamics. At the end of the chapter, a short list of analysis methods and strategies is proposed for detecting and measuring landscape “anthropization.”