Comparative research on Mediterranean-type ecosystems over the past several decades has largely focused on evergreen, sclerophyllous vegetation. Little attention has been given to comparative research on ecological structure and community diversity in the coast al transitions from mediterranean climate zones to winter rainfall deserts. This has been a particularly important oversight by the MEDECOS research community, since the Mediterranean desert transition zones are potentially as diverse as their related "true" Med iterranean counterparts. These ecotonal areas appear to support a large diversity of plant taxa, many of which are endemic (e.g. Raven and Axelrod 1978;Shmida 1985; Cowling and HiltonTaylor, in press).It is clear that the vege tation in each of these zones is under increasing pressure as population numbers rise, and the demand for economic security increases. Threats are diverse and include tho se associa ted with the mining industry, as well as overgrazing by small livestock (goats and sheep ), agriculture and urban development. Lack of research in these arid are as has not encouraged good land use practices and all three areas discussed here are poorly conserved. As pressure on these marginal farming area s increases, so should the efforts to improve, sustain and restore them. These efforts should be based on a scientific understanding of the dynamics of the vegetation, an understanding of the processes leading to degradation as well as those involved in the rehabilitation and restoration of vegetation. This requires both theoretical inve stigations into vegetation dynamics as well as the development of practical procedures by which to evaluate such theory.The comparison of the characteristics of different systems is one of the oldest approaches in ecology, and one which is very familiar to researchers in mediterranean-type ecosystems.
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