The rating of biodiversity in and and semiarid regions on the basis of ecological function and genetic traits of adaptation to severe environmental stresses produces significantly higher values, than that based solely on the commonly applied structural criteria of forms of life and levels of organization. The indirect driving forces of biodiversity impoverishment listed in the Global Biodiversity Strategy that are particularly effective in and and semi-arid regions are (a) population growth, (b) economic systems and policies that fail to value the environment and its natural resources; (c) inequity in the ownership, management and flow of benefits from both the use and conservation of biological resources;, and (d) weakness in legal and institutional systems. The most effective direct human impacts are (a) habitat destruction and fragmentation, (b) overexploitation of biological resources, (c) biological invasion, and (d) agriculture. The problem in and and semiarid regions, particularly in developing countries, is exacerbated by the lack of knowledge and awareness, the paucity of research, and the diminishing number of competent systematists. This paper discusses the theoretical and practical aspects of each of the indirect driving forces, and the direct human impacts on biodiversity, and reviews case studies related to these impacts, with special reference to those carried out in and and semiarid regions. These studies include monitoring of the human impact on land cover by remote sensing, effects of landuse on species diversity, impact of habitat fragmentation by summer resorts on coastal dunes, consequences of protection from grazing on biodiversity, comparison of biodiversity in nature reserves and the traditional hema system with that of nearby territories, and the impact of desertification on animal life and endangered species. Case studies also include the tools applied for biodiversity conservation in and and semiarid lands with special emphasis on endangered species, restoration of degraded habitats and their biodiversity, the significance of nature reserves and captive breeding, the importance of conserving the populations below the species level throughout their geographical range of distribution, and ecotonal biodiversity. (C) 2003 Elsevier Science Ltd.
