RESTORATION IN A CHANGING WORLD: CASE STUDIES FROM CALIFORNIA INTRODUCTION TO SPECIAL ISSUE

As the human footprint occupies an ever increasing proportion of the earth’s surface and resources (e.g., Vitousek 1994; Vitousek et al. 1997; Tilman et al. 2001; Wackernagel et al. 2002), conservation biologists must develop strategies that both protect remnant natural areas and rebuild the ecological integrity of highly altered landscapes (Young et al. 2005). In almost no other region on earth is this need more imperative than in California. California is home to over 36 million residents and has roughly the 7th largest economy in the world, making it a highly human-influenced environment. Yet, the state possesses an exceptional diversity of ecosystems and taxa, many of them threatened with extirpation. The California Floristic Province has been classified as a World Biodiversity Hotspot because of its exceptional level of species endemism and the conservation challenges it faces (Meyers et al. 2000; Konstant et al. 2005). While the mission of the California Botanical Society is to advance the science of western American botany, today it is evident that a key element to that science is learning how to restore native plant communities so that native biodiversity can be sustained over time. There is still much to be learned and the science of restoration ecology is still in its infancy. Furthermore, the practice of ecological restoration must be accomplished in the face of dynamic global changes. In 2005, our board was invited to sponsor a symposium at the 2006 annual meeting of the Society for Conservation Biology (SCB) to be held in San Jose, CA in June 2006. The theme of the conference was ‘‘Conservation without Borders’’. This opportunity inspired us to organize the symposium ‘‘Restoration in a changing world: Case studies from California’’ which took place on Wednesday, June 28, 2006. This special issue is the culmination of that effort. The symposium delivered eight 15 min papers by Michael Vasey, Stuart Weiss, Jeffrey Corbin, K. Blake Suttle, John Callaway, Nathan Stephenson, Jodi McGraw, and Alison Purcell. There was a remarkable congruence between most of these talks and, in fact, several other talks and symposia at the SCB meeting. The common theme was that the threats posed by such elements of global change as climate change (including associated sea level rise), invasion of non-native species, alteration of disturbance regimes, and the input of nitrogen via air pollution are exerting unprecedented pressure on biodiversity, trophic interactions, and the physical structure of ecosystems in California and throughout the world. As many authors have recognized, multiple components of global change are also capable of interacting with each other to affect ecological interactions and the prospects for successful restoration (e.g., Dukes and Mooney 1999; Weiss 1999; Vila et al. 2007). Although Rein et al. (this volume) did not participate in the symposium, we welcome their contribution to this special issue as yet another good example of the challenges that invasive species pose to restoration practitioners. Taken collectively, the results presented in the symposium and in this special issue suggest that the challenges that face sensitive ecosystems will be substantial and will, in some cases, require wholly new strategies if we are to successfully preserve biodiversity and ecosystem function in this age of global change. California is hardly unique in North America, let alone worldwide, in confronting the challenges of climate change, invasive species, and changing land-use. Indeed, nearly every part of the globe must deal with one or more of them. This special issue considers the future of conservation and restoration efforts in California in the face of the myriad threats posed by the local and regional manifestations of several of the most important drivers of global change. We hope that insights gained from these papers can be helpful to scientists and habitat managers in other regions who must also confront the challenge of restoring ecosystems in the face of these challenges.