Biodiversity in Critical Transition Zones between Terrestrial, Freshwater, and Marine Soils and Sediments: Processes, Linkages, and Management Implications

Abstract

The boundaries between aquatic and terrestrial ecosystems, and particularly the interfaces among soils, freshwater sediments, and marine sediments, are known as “critical transition zones” (CTZs). These interfaces are critically important because they are dynamic habitats that control or influence the movement of organisms, nutrients, materials, and energy within and across landscapes through linked ecosystem processes. They are therefore not only vital to local processes within the transition habitat itself but also have significant effects on adjacent ecosystems. The papers in this volume by Bardgett and others (2001), Levin and others (2001), and Ewel and others (2001) are the results of an international workshop convened by the Committee on Soil and Sediment Biodiversity and Ecosystem Functioning of the Scientific Committee on Problems in the Environment (SCOPE) to address the following topics: (a) biodiversity in the soils and sediments of CTZs, (b) the ecosystem processes that occur within these zones, (c) CTZs as pathways connecting adjacent ecosystems, and (d) the implications for the management for these habitats. Levin and others survey marine interfaces (estuaries, coastal wetlands), whereas Bardgett and others discuss terrestrial interfaces (that is, the zones between land and both fresh and marine waters). Ewel and colleagues offer a consideration of the management and restoration challenges faced by scientists and managers today, with emphasis on the need for greater collaborative efforts by all interested parties. The papers presented here reflect the current thinking on a subset of all existing types of critical transition zones. There are many other types of transition zones that are not covered in this issue (riparian zones, freshwater wetlands, and so on); however, the issues of concern raised by these authors for marine and terrestrial CTZs are analogous. It is our hope that this strict focus on the problems of marine and terrestrial CTZs will serve to stimulate the study of more diverse types of CTZs. It is particularly important that future work address land–water interfaces because of the many urgent environmental problems that are centered there. For example, the recently released National Research Council report Grand Challenges in Environmental Sciences (NRC 2000) cited water resources, land-use dynamics, and biodiversity among its list of the most pressing areas for environmental research today. Of particular concern is our need to understand how changes in the landscape affect water supplies and the flow of sediments to rivers Received 14 March 2001; accepted 16 March 2001. *Corresponding author; e-mail: diana@nrel.colostate.edu Ecosystems (2001) 4: 418–420 DOI: 10.1007/s10021-001-0103-3 ECOSYSTEMS