|The Arabian Peninsula constitutes one of the largest contiguous arid zones in the world. Within this context of aridity the region is surprisingly diverse in climatic conditions, soil types, landscapes, and land-use patterns. Agroecological r~iches occur with edaphic conditions that can deviate substantially from those of surrounding areas and often have higher biomass or agricultural productivity. In the context of global climate
change, Chi's agroecological diversity is also an important source of abiotjcstrcss resistance in plants against drought, high temperatures, and salinity. However, the region is also ecologically fi-agile. Firstly, it is vulnerable to natural processes, such as primary salinization, and wind and water erosion. In addition, overgrazing, fuel-wood extraction, drought, and depletion of fossil water resources are increasingly threatening the sustainability of the natural resource base and may lead to potentially irreversible desertification. A rational approach to combating desertification req~~ires in the first place differentiating true degradation, as a result of over-exploitation, from processes and conditions that are the natural outcome of the biophysical limits imposed by harsh climates that prevail in the Arabian Peninsula. Such an approach necessitates the development of agroecological frameworks, which allow assessing ~hc spatial and temporal variations in the natural resource base and associated land-use systems. To combat desertification effectively, a good agroecological character~zation is of vital importance. Numerous thematic surveys in the form of soil survey reports, climatic maps, and groundwater surveys already exist in the Arabian Peninsula. However, the challenge is 'to develop integrated land and water resource information systems, based on CIS-tecl~nology. This integration will allow linkage of multidisciplinary,
geographically referenced databases at different resolutions, and to develop decision support systems for more sustainable land use management and resource i~sc regulations. By bringing together information sources from the international public domain and the Arabian Peninsula itself, and processing them with state-of-the-art GIs
technology, this report aims to initiate this process of data integration at the regional level. As such it will be of value for agricultural research planning, biodiversity management, land use planning, and public awareness at the national and regional levels. We hope it will fill a major gap in our understanding of the agro-ecological
diversity, vulnerability, and agricultural productivity of one of the most important arid
regions in the world.