Biodiversity and Conservation Biology of Coastal Transition Zones from Mediterranean to Desert Ecosystems: An Intercontinental Comparison

Abstract

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.

Islands, Exotic Herbivores, and Invasive Plants: Their Roles in Coastal California Restoration

“…Northwest Baja California, Mexico, where Mediterranean coastal vegetation continues southward from California, has also experienced recent accelerated development. As a result few undisturbed coastal lands exist on either side of the border (Reid & Murphy 1995; Esler et al 1998).…”

“…1) (SEDUE 1989; Halvorson 1994). Consequently, these islands hold potential for the conservation of California Mediterranean coastal ecosystems (Esler et al 1998; Walter 1998). Restoration has been underway on U.S. California Islands for over 15 years (Davis et al 1994; Halvorson 1998), and recent efforts have demonstrated the conservation value of islands in northwest Mexico (Donlan et al 2000; Tershy et al 2002; Donlan et al in press).…”

Propolis from Chilean Matorral Hives

“…This community becomes lower and m ore scrubby on drier slopes, and mostly arboreal in shaded canyon ("quebradas") where moisture levels are higher (Esler et al, 1998). The site is located in a degraded area dom inated by low sclerophyll forest ("m atorral").…”