This is why WWF has focused its attention on critical ecoregions, the Global 200 (WWF 2000, Figure 1). These constitute a set of ecoregions selected among all terrestrial, marine, and freshwater habitats around the world through a science-based ranking effort. To identify the most outstanding examples, this ranking is based on a comparative analysis of biodiversity data throughout the world, using the ecoregions as the units of analysis. The Global 200 includes representations of all major habitat types in each major biogeographic unit. The objective of this ranking is to prioritize conservation actions throughout the world (Olson & Dinerstein 1998, Olson et al. 2000, 2001). WWF and partners are thus shifting from site-based projects to planning and action at the scale of ecoregions, in an approach called Ecoregion Conservation (ERC). Ecoregion Conservation allows us to achieve conservation goals that cannot be attained at other scales of planning and action (BOX 2). Similar approaches are taken by most other major environmental organizations throughout the world, including The Nature Conservancy, Conservation International, and others (Bright & Mattoon 2001).
Minimum conservation targets to achieve the goals of ecoregion conservation (ERC)
The term biodiversity describes the full expression of life on the planet, from genes to species, to ecological interactions, to whole ecosystems. The ERC approach is designed to address the conservation requirements of the full experience of biodiversity; and thus the fundamental goals of biodiversity conservation help shape the overarching Vision for an ecoregion. In order to be rigorous and effective in ERC, we should focus conservation activities on five specific biodiversity targets:
Distinct communities, habitats, and species assemblages (distinct units of biodiversity)
A primary conservation target is the representation of distinct biogeographic subregions, habitats, communities, and assemblages of species. Representation of specific assemblages may also be appropriate. The particular combination of units to be represented in each ecoregion strategy will vary depending on: a) the distinguishing features of each ecoregion, and b) the availability and quality of information on patterns of biodiversity. We should strive to represent and conserve habitats as well as the full diversity of species in each ecoregion.
Large expanses of intact habitat and intact biotas
Empirical studies demonstrate that large areas of intact natural habitat are best for conserving the full range of species, habitats, and natural processes. However, intact ecosystems and biotas are increasingly rare around the world. In particular, top predators and larger vertebrates are disappearing rapidly in most ecoregions as human activities convert and fragment natural habitats and exterminate populations of vulnerable species via overexploitation.
Keystone ecosystems, habitats, species, or phenomena
At ecoregional scales, certain kinds of habitat may exert a powerful influence on biodiversity in surrounding habitats and across the whole ecosystems. Their persistence and intact ecological functioning may be critical for many species and ecological processes in neighboring areas.
Large-scale ecological phenomena
The conservation of distinctive large-scale ecological processes, such as hemispheric-scale animal migrations, requires a combination of site-specific, regional, and policy-level efforts applied over vast continental areas or widely disjunct regions. Habitats or sites that may not be particularly distinctive (e.g., characterized by high richness or endemism) or intact may still act as critical habitat for migratory species. Conservation of such phenomena must be linked with ecoregion-level activities and coordinated among different ecoregions.
Species of special concern
Some species that are heavily hunted, depleted in numbers, or highly specialized in their habitat requirements run the risk of falling through the cracks of ERC, a process which gives greater weight to representation than single-species conservation efforts. However, in many ecoregions, targeted efforts to restore populations of sensitive species and their habitats are central to ERC because they serve as focal species for planning.
From: Dinerstein et al. 2000. A Workbook for developing biological assessments and developing Biodiversity Visions fore ecoregion conservation. Part I: Terrestrial Ecosystems. WWF- Conservation Science Program.
Planning and action at the ecoregional scale and for the long term are essential to achieve
conservation results and to link human development opportunities to the maintenance of biological diversity. A cornerstone of ERC is a Biodiversity Vision (Box 3). A Biodiversity Vision is an analysis of patterns of biological diversity and threats and opportunities for conservation at the ecoregional level that serves as a blueprint for conservation action - a design of what the ecoregion's biodiversity will need to survive over the long term. A Biodiversity Vision is thus a planning tool, usually in the form of a document like this, aimed at guiding biodiversity conservation activities in the ecoregion. A Biodiversity Vision sets a number of biodiversity conservation goals, based on basic and widely accepted principles of conservation biology, and identifies critical areas to be conserved, managed or restored in order to meet those goals. These areas are identified through a science-based process that relies on the best available biodiversity data and socioeconomic information. Through this process we develop a Biodiversity Conservation Landscape, represented in a map, that shows how the ecoregion will look in 50-100 years if we are successful at conserving its biodiversity and ecological processes. This Biodiversity Conservation Landscape is a central piece of the Biodiversity Vision, and its representation in a map helps to focus conservation activities on those areas of the ecoregion that will render the best results for biodiversity conservation. A Biodiversity Vision also identifies clear conservation targets and serves as a tool to prioritize conservation actions in the ecoregion.