Ecoregions in Ascendance: Reply to Jepson and Whittaker

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1 Comments Ecoregions in Ascendance: Reply to Jepson and Whittaker ERIC WIKRAMANAYAKE,* ERIC DINERSTEIN,* COLBY LOUCKS,* DAVID OLSON,* JOHN MORRISON,* JOHN LAMOREUX,* MEGHAN MCKNIGHT,* AND PRASHANT HEDAO *Conservation Science Program, World Wildlife Fund United States, th Street NW, Washington, D.C , U.S.A. Environmental Systems Research Institute, Inc., Redlands, CA 92373, U.S.A. Introduction In their essay, Jepson and Whittaker (2002 [this issue]) express three aims: (1) to place the World Wildlife Fund ( WWF ) ecoregions (Olson et al. 2001; Wikramanayake et al. 2001) in context with alternative systems for setting conservation priorities; (2) to express concern about the explicitness, transparency, and repeatability of the methods employed to define and delineate ecoregions; and (3) to ask whether the WWF ecoregions improve upon existing schemes of representing biodiversity (which they attempt to investigate by performing a qualitative test with Indonesia as a case study). Their essay contains a number of misrepresentations of our ecoregion approach. In the interest of brevity, we address only the major issues in this reply. We begin by arguing for the value of ecoregions, outlining the rationale behind the ecoregion framework and the delineation process, and comparing these with other efforts. The approach is detailed explicitly by Wikramanayake et al. (2001) and others ( Ricketts et al. 1999; Abell et al. 2000; Dinerstein et al. 2000). Why Ecoregions? Ecoregions may be a relatively new concept in conservation biology, but they are based on classical biogeography. Although a single institution like WWF may actually produce an ecoregion map, the ecoregions themselves Address correspondence to E. Dinerstein, eric.dinerstein@ wwfus.org Paper submitted August 13, 2001; revised manuscript accepted August 20, are developed through extensive collaboration with biogeographers, taxonomists, conservation biologists, and ecologists from around the world. Since 1999, three of the leading international nongovernmental organizations WWF, The Nature Conservancy ( TNC ), and Conservation International (CI ) and many other conservation partners around the world have identified ecoregions or larger biogeographic units such as hotspots (CI ) as an appropriate scale for conservation priority setting and planning. These organizations have found that ecoregions provide the critical spatial link between global priority-setting efforts and site-based assessments. Perhaps the most attractive feature of ecoregions is that they define biogeographic units that are most suitable for meeting a fundamental goal of biodiversity conservation: the representation of all habitats and distinct biotas in networks of conservation areas. The use of ecoregions allows us to avoid redundancy and enhance complementarity in the design of reserve networks better than do approaches that rely on political units to determine conservation priorities. Developing conservation strategies within a framework of ecoregions also allows us to address the ecological processes that maintain biodiversity and to protect populations of species with large spatial needs that cannot be accommodated at the site scale or that do not adhere to political boundaries ( Dinerstein et al. 2000; Groves et al. 2000; Mace et al. 2000). The magnitude of the shift to ecoregions for conservation planning is worth noting for the benefit of conservation biologists unaware of this trend. The WWF has targeted 189 of the planet s 867 terrestrial ecoregions, 15 freshwater ecoregions, and 24 marine ecoregions for such analyses. Within a few years, TNC plans to finish ecoregion strategies for all 62 of its U.S. ecoregions, and CI plans to complete similar analyses for all 25 hotspots ( Myers et al. 2000), many of which overlap with the Global 200 Ecoregions identified by WWF (Olson & Dinerstein 1998). The, Pages

2 Wikramanayake et al. Ecoregions in Ascendance 239 WWF is collaborating with both organizations on several of these efforts. Regional analyses, such as those conducted for the Nearctic, Neotropics, and Indo-Pacific ( Dinerstein et al. 1995; Ricketts et al. 1999; Abell et al. 2000; Wikramanayake et al. 2001), constitute the foundation for the WWF s efforts and have received favorable reviews in the conservation biology literature ( Pimm 1999; Terborgh 1999; Caicco 2000; Cassin 2000; Ebersole 2000; Ruhren 2000). Other regional assessments in this series are in press ( Burgess et al. 2002) or in preparation (Afrotropics freshwater, Palearctic, Neotropics). Given the trend among conservation nongovernmental organizations, we predict that within 2 years, submissions on the practice of ecoregion-based conservation will become increasingly prevalent in peer-reviewed journals such as. Even Jepson (1999) acknowledges the usefulness of our ecoregion framework to the conservation of biodiversity. In a rather critical review of BirdLife International s landmark publication, Endemic Bird Areas of the World: Priorities for Biodiversity Conservation, he writes: In short, the meat in this book does not justify the 846 pages. WWF US has incorporated endemic bird areas (EBAs) in the ecoregion approach which combines a representation and hotspot approach in the Global 200. Ecoregions probably represent the culmination of the biologist s perspective on biodiversity priorities. Jepson confuses, as he has elsewhere ( Jepson & Canney 2001), representation with prioritization. The Dasmann-Udvardy and Omernik-Bailey assessments are representation systems, as are WWF s ecoregions (Olson et al. 2001). In contrast, strategic prioritization highlights areas essential for the conservation of irreplaceable and threatened biodiversity (Margules & Pressey 2000). Conservation International s hotspots (Myers et al. 2000), WWF s Global 200 Ecoregions (Olson & Dinerstein 1998), BirdLife International s EBAs (Stattersfield et al. 1998), and the World Conservation Union ( IUCN) and WWF s centers of plant diversity ( IUCN & WWF 1995) exemplify prioritization systems that are highly congruent despite their differing scales of analysis ( da Fonseca et al. 2000). Ecoregions in Context Here we address Jepson and Whittaker s (2002 [this issue]) suggestion that WWF ecoregions are inferior to existing systems of classification. Jepson s specific criticism of WWF s ecoregions is that they conflict with the Dasmann-Udvardy system of biogeographic representation. They do not. Rather, ecoregions represent continuous updating and improvement of this system, with the goal of reconciling the numerous idiosyncratic approaches that have developed over the last few decades into a standardized global scheme. They also introduce the concept to the current generation of conservation planners and incorporate aquatic systems. Where the implementation of existing frameworks is weak, the delineation of ecoregions will strengthen it; where implementation is strong, as in Indonesia, it will reinforce it and address remaining gaps as demonstrated below. Because of their biogeographic baseline, ecoregions reflect the distribution of species and communities more accurately than do units derived from models based on combinations of coarse-scale biophysical features such as rainfall and temperature, which Jepson and Whittaker view as objective, transparent, and repeatable. Bailey s (1998) terrestrial ecoregions are derived primarily from such models and are based on global-scale biophysical data. The resulting ecoregion units are excessively large for regional planning and do not effectively reflect biogeographic patterns determined largely by historical processes, particularly in island systems such as in the Indo- Pacific. Bailey s system also ignores many tropical islands with extraordinary levels of endemism but too small in size to be classified in his approach. Dasmann (1974) and Udvardy (1975) were the first to map a global system of biogeographic units (referred to as biotic provinces) within a framework of realms and biomes. Their biotic provinces are based on known biogeographic patterns, rather than on biophysical models, and are thus comparable to ecoregions in their derivation and intent (i.e., identifying distinct biotas). But the biogeographic resolution of Dasmann and Udvardy s biotic provinces is considerably coarser than our system of terrestrial ecoregions. We have identified 867 terrestrial ecoregions for the world (Olson et al. 2001), compared with the 198 and 193 units of Dasmann s and Udvardy s systems, respectively. The increased resolution is most apparent in the tropics (between the Tropics of Cancer and Capricorn), where Dasmann (1974) and Udvardy (1975) identified 115 and 117 units, respectively, compared with 463 identified in the WWF terrestrial ecoregion map of the world. A finer-scale example that covers part of Indonesia Irian Jaya, the western part of the island of New Guinea, and the country of Papua New Guinea makes the point even more clearly. Dasmann and Udvardy treat the island of New Guinea as a single unit, whereas we distinguish 12 ecoregions consisting of four lowland and four montane broadleaf forests, one alpine scrub ecoregion along the central cordillera, one mangrove forest, one freshwater swamp forest, and one savanna-grassland ecoregion. In sum, the Bailey, Dasmann, and Udvardy models, however useful as a broad framework for understanding biogeography, are far too coarse for either representation or prioritization analyses (sensu Jepson). Thus, MacKinnon and Wind (1981) identified a third, finer-scale tier, biounits, which they nested within Udvardy s biogeographic provinces. MacKinnon subsequently applied the biounit (and subunit) concept to a broader regional area, from Pakistan

3 240 Ecoregions in Ascendance Wikramanayake et al. to Papua New Guinea ( MacKinnon & MacKinnon 1986; MacKinnon 1997 ). Although this step facilitates regional planning, the biounit classification mixed distinct biomes, making representation analyses difficult. For instance, a single biounit can be comprised of mangroves, tropical dry deciduous forests, thorn scrub, tropical semi-evergreen forests, and tropical moist forests. These habitat types differ not only in characteristic species, but also in ecological dynamics such as species assemblages, natural densities of large herbivores, vectors for seed dispersal, types of natural-disturbance regimes, response to disturbance, and degree of resiliency. Mangroves are ecological systems vastly different from tropical dry thorn scrub, and the conservation planning and representation of each is improved by recognizing them as separate ecoregions (if, for example, the area of mangroves is sufficiently extensive to meet the spatial criterion of an ecoregion). Thus, in our analysis of terrestrial ecoregions of the Indo-Pacific region ( Wikramanayake et al. 2001), we used MacKinnon s construct of the original habitat to replace biounits with ecoregions within the Udvardy framework. To subdivide Udvardy s biogeographic realms ( Fig. 1), we identified bioregions. Bioregions are based on accepted biogeographic demarcations and have been described in detail, with maps, by Wikramanayake et al. (2001). Within a given bioregion, ecoregions can be nested under different biomes. In other words, bioregions allow us to achieve a further level of representation in a global or regional priority portfolio by capturing a minimum number of ecoregions within each biome occurring in each bioregion. For example, the Western Ghats Mountains along India s western coast are clothed in rainforests, as are the mountains of central Borneo. But the flora and fauna of the Western Ghats are distinctly different from those in central Bornean forests: the former has Nilgiri tahr (Hemitragus hylocriusi ), lion-tailed macaques (Macaca silenus), Nilgiri langurs (Presbytis johnii ), tigers, and a diverse forest association, whereas the latter has orangutans (Pongo pygmaeus), gibbons, Sumatran rhinoceros (Dicerorhinus sumatrensis), and forest associations dominated by Dipterocarpaceae spp. To conserve one or the other as a representative rainforest habitat of Asia in a global or regional conservation strategy would be insufficient. Our analysis carefully considered previous approaches, such as EBAs (Stattersfield et al. 1998) and centers of plant diversity ( IUCN & WWF 1995). Where these efforts distinguished distinct biotas at a high level of resolution, we based our ecoregion delineation on them. For example, in western Indonesia we used the maps of the original vegetation from MacKinnon (1997), but in eastern Indonesia we used the EBAs (Stattersfield et al. 1998) because we considered them finer and more robust discriminators of biodiversity for this system of small island complexes. We did not use hotspots (Mittermeier et al. 1999) because these units are regional in extent and are based on a combination of high biodiversity and threat, rather than strictly on biogeography. Explicitness, Transparency, and Repeatability We delineated ecoregions according to a set of rules based on biogeography, habitat type, and elevation. Wikramanayake et al. (2001) explicitly describe these rules and define the biogeographic units and all indices and thresholds that were used to delineate and assess ecoregions for the Indo- Pacific region. To make the process of ecoregion delineation transparent and repeatable, we have made available all the information we used from Wikramanayake et al. (2001). We have also provided lists of all contributors and Figure 1. Hierarchy of spatial units used in the conservation assessment of the Indo-Pacific.

4 Wikramanayake et al. Ecoregions in Ascendance 241 reviewers for the respective ecoregions. As in any attempt to represent nature in spatial units, we do not expect unanimous acceptance of the ecoregion boundaries as we have presented them. We do hope that many regional biogeographers and conservation biologists, once they understand how the global map incorporates published, widely used classification schemes, will find it acceptable. Ecoregions Misrepresented: Gestalt, Experts, and Indonesia If nature could be fit into a one-size-fits-all framework, our task would be simple. Unfortunately, it does not. A map of eastern Indonesia shows a plethora of lines that have sprung up around Wallace s now-famous line all in attempt to refine Wallace s original effort and observations. This is because the biodiversity of archipelagos results from a complex suite of biogeographic variables including species vagility and origin, geologic history, geomorphology, landform, size, and interisland distance. Compounding the problem of detecting patterns of biogeography is a lack of comprehensive and reliable biodiversity data for many places on Earth. There are no biological databases that are uniform in detail and resolution for the entire planet. Thus, developing a global framework of ecological units necessitates working with uneven information. At times, this requires sifting through and combining the best available information from several sources and using various biological and geophysical parameters. In his aforementioned review of EBAs, Jepson (1999) commends us for incorporating them into the Global 200 Ecoregion analysis. But in their current essay, Jepson and Whittaker (2002, this issue) criticize it as part of a gestalt approach to ecoregion delineation. Yet they defend the Dasman- Udvardy-MacKinnon-Wind EBA approach that was used to guide planning for Indonesia s current protected-area system even though it uses different types of data and data sources, and zonal and azonal features ( Jepson and Whittaker s words). It is unclear to us how such an approach is less a gestalt synthesis than ours. We also believe that expert review and input strengthen the validity and accuracy of ecoregions and our approach, despite Jepson and Whittaker s skepticism. The WWF Ecoregion Approach and the Goal of Representation of Indonesia s Protected-Areas System Much of what has been described above can be viewed as a rather narrow set of academic disagreements best suited for a biogeography journal or a debate among participants at a workshop on ecoregion conservation planning in Indonesia. But Jepson and Whittaker s critique assumes real-world significance when the issue becomes the relationship between designing biogeographic frameworks and establishing representative networks of protected areas. They claim that Given that the existing schemes, despite flaws, have achieved their purpose in Indonesia... we question the wisdom of introducing the WWF ecoregion system. This statement is the extent of their test of the efficacy of ecoregions against the existing planning system. We strongly disagree with their opinion, believe that the ecoregion approach improves on the previous framework, and present a quantitative test of our own below. Ecoregions are ultimately tools for conservation planning. Although the ecoregion analyses point out many of the strengths of the existing design of a protected-areas system for Indonesia, it also highlights some significant gaps. A recent assessment by Derek Holmes ( by Wikramanayake et al. 2001) projects that, at current rates of destruction, the remaining intact lowland forests of Sumatra and Kalimantan will disappear within the next 5 and 9 years, respectively. Taking this analysis further, we can compare current levels of protection in lowland and montane forest ecoregions of Sumatra, Java, Borneo, and Sulawesi. Almost 15% of the montane forests are contained within IUCN category I IV protected areas, but less than 6% of the remaining lowland forests are protected ( Table 1). Thus, protection is biased toward inclusion of montane forests, which are largely unproductive for agriculture and too steep for logging, plantations, and settlements, whereas the rich lowland rainforests of Indonesia remain underrepresented within the protectedareas system. An analysis based on ecoregions illustrates this disparity in representation better than one based on classification schemes promoted by Jepson and Whittaker that do not effectively distinguish montane and lowland habitats. Table 1. Comparison of degree of protection (PA, protected area) in lowland and montane forests of Java, Sumatra, Borneo, and Sulawesi. Protected areas (km 2 )* Forest IUCN I-VIII IUCN I-IV Total area of lowland and montane forests (km 2 ) I VIII in PA (%) I IV in PA (%) Lowland 80,029 68,519 1,221, Montane 53,630 46, , *This analysis uses World Conservation Monitoring Centre and Asian Bureau for Conservation (1997 ) protected areas and does not include those designated as proposed.

5 242 Ecoregions in Ascendance Wikramanayake et al. Jepson and Whittaker also suggest that ecoregions can divert conservation efforts from biologically important areas. They are concerned that treatment of the lowland forests of Sulawesi as a single ecoregion may suggest to planners that targeting resources to any peninsula in Sulawesi is equally good, thereby detracting from important and high-priority conservation areas such as the northern Minahasa peninsula. In reality, any intelligent, competent conservation planner will look carefully at biogeographic patterns to ensure adequate representation within a given ecoregion, typically by creating biogeographic subdivisions, a method used by the WWF, CI, and TNC (see Dinerstein et al. 2000). Jepson and his colleagues have over the past 2 years criticized the prioritization efforts of BirdLife International s EBAs, CI s hotspots, and WWF s terrestrial ecoregion analysis without offering the scientific community a compelling alternative for representation of global biodiversity or priority setting. In their critiques of all three approaches they are literally and figuratively all over the map, offering conflicting recommendations. For example: in a critique of EBAs, Jepson (1999) proposes that WWF ecoregions are better units for prioritization and representation than are targets based on range-restricted birds as proposed by BirdLife; in a critique of hotspots, Jepson and Canney (2001) evaluate hotspots using nonbiological criteria and chastise CI for not doing a better job of representing biodiversity, when hotspots is not a representation scheme but a prioritization scheme. 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