This ecosystem profile, together with profiles under development for other regions at this time, includes a new commitment and emphasis on using conservation outcomes—targets against which the success of investments can be measured-as the scientific underpinning for determining CEPF's geographic and thematic focus for investment.
Conservation outcomes are the full set of quantitative and justifiable conservation targets in a hotspot that need to be achieved in order to prevent biodiversity loss. These targets are defined at three levels: species (extinctions avoided), sites (areas protected) and landscapes (corridors created). As conservation in the field succeeds in achieving these targets, these targets become demonstrable results or outcomes. While CEPF cannot achieve all of the outcomes identified for a region on its own, the partnership is trying to ensure that its conservation investments are working toward preventing biodiversity loss and that its success can be monitored and measured. CI's Center for Applied Biodiversity Science is facilitating the definition of conservation outcomes across the 25 global hotspots, representing the benchmarks against which the global conservation community can gauge the success of conservation measures.
Conservation outcomes focus on biodiversity across a hierarchical continuum of ecological scales. This continuum can be condensed into the three levels: species, sites and landscapes. The three levels interlock geographically through the presence of species in sites and of sites in landscapes. They are also logically connected. If species are to be conserved, the sites on which they live must be protected and the landscapes must continue to sustain the ecological services on which the sites and the species depend. At the landscape level, conservation corridors (within which sites are nested) can sometimes be defined and investments can be targeted at increasing the amount of habitat with ecological and biodiversity value within these corridors. Given threats to biodiversity at each of the three levels, quantifiable targets for conservation can be set in terms of extinctions avoided, sites protected and, where appropriate, conservation corridors created or preserved. This can only be done when accurate and comprehensive data are available on the distribution of threatened species across sites and landscapes.
Defining conservation outcomes is therefore a bottom-up process through which species-level targets are defined first and based on the species information, site-level conservation targets are identified. Landscape-level targets are delineated subsequently, if appropriate for the region. The process requires knowledge on the conservation status of individual species. This information has been accumulating in the Red Lists of Threatened Species developed by IUCN and partners. The Red List is based on quantitative, globally applicable criteria under which the probability of extinction is estimated for each species. Species outcomes in the Eastern Arc Mountains and Coastal Forests hotspot include those species that are globally threatened (Vulnerable, Endangered and Critically Endangered) according to The 2002 IUCN Red List of Threatened Species. Outcome definition is a fluid process and, as data become available, species-level outcomes will be expanded to include other taxonomic groups that previously had not been assessed, as well as restricted-range species. Avoiding extinctions means conserving globally threatened species to make sure that their Red List status improves or at least stabilizes. This in turn means that data are needed on population trends; for most of the threatened species, there are no such data.
Recognizing that most species are best conserved through the protection of the sites in which they occur, site outcomes are defined for each target species. Site outcomes are focused on physically and/or socioeconomically discrete areas of land that harbour populations of at least one globally threatened species. These sites need to be protected from ecological transformation to conserve the target species. Sites are scale-independent and, ideally, should be manageable as single units.
Corridor outcomes are focused on landscapes that need to be conserved to allow the persistence of biodiversity over time. Species and site outcomes are nested within corridors. The goal of corridors is to preserve ecological and evolutionary processes, as well as enhance connectivity between important conservation sites by effectively increasing the amount of habitat with biodiversity value near them. Unlike species and site outcomes, the criteria for determining corridor outcomes are being defined and this is presently an important research front. CABS will make the data on conservation outcomes publicly available on this Web site.
To define the species outcomes for this hotspot, all globally threatened species in The 2002 Red List of Threatened Species that are found in the Eastern Arc Mountains and Coastal Forests hotspot were identified. Data were compiled for each species on its conservation status and known distribution. Site outcomes were determined by identifying all sites that are important for each globally threatened species. Following a review of the species and site outcomes and expert consultations, corridor outcomes were not defined for this hotspot. Conservation corridors (landscape conservation units consisting of core sites and the surrounding matrix) did not make sense in this naturally fragmented, relatively small hotspot. However, it will be important to reconnect forest patches that have only become isolated in recent decades as a result of human activities. Failure to reconnect forest patches within a formerly continuous site will inevitably mean the extinction of numerous species as the habitat patches fall to sizes that can no longer sustain their biodiversity due to island biogeography effects (Newmark 1991, 2002; Brooks et al. 2002).
The definition of the conservation outcomes drew heavily on the research findings of a large number of scientists who have worked intensively in this hotspot over the last three decades and who have contributed to various compilations of primary field data (Lovett & Wasser 1993; Burgess et al. 1998, Burgess & Clarke 2000; Newmark 2002; WWF-EARPO 2002; WWF-US 2003a,b). The key sources of data on threatened plants included the Flora of Tropical East Africa (see Beentje & Smith [2001] for details of publication), the TROPICOS database (MBG 2003), and a database compiled by Q. Luke. Data on faunal species distributions in Tanzania were drawn from the University of Dar es Salaam biodiversity database (Howell & Msuya 2003). The work to define national Important Bird Areas (IBAs) was also an important source of data. The IBA process in Kenya and Tanzania (coordinated by Nature Kenya and the Wildlife Conservation Society of Tanzania as the BirdLife International partners for these countries) had already compiled data for threatened and restricted-range birds and their key sites (IBAs). These data were already in the World Bird Database at BirdLife International. The IBAs provided a starting point for including other aspects of the biodiversity of this hotspot to identify key biodiversity areas, or site level conservation outcomes.
The results of the outcome definition indicate that 333 globally threatened (Red List) species occur in the hotspot, with 105 species being represented in Kenya and 307 in Tanzania (Table 1). The globally threatened flora and fauna in the hotspot are represented by 236 plant species, 29 mammal species, 28 bird species, 33 amphibian species and seven gastropod species. Of the 333 globally threatened species in the hotspot, 241 are Vulnerable, 68 are Endangered and 24 are Critically Endangered.
The full list of species outcomes is provided in Appendix 1 (
Download the Appendices to view each appendix.) The species outcomes are based on the 2002 IUCN Red List, which is quite good for several taxonomic groups. However, Red List data for plants is badly in need of updating. The 2002 Red List includes some widespread plant species in this hotspot, others that are in far greater danger of extinction because their restricted ranges have not yet been assessed (Q. Luke & R. Gereau pers. comm.). Gereau and Luke (2003) estimate the total number of globally threatened plant species in the hotspot is probably 1,200 or more, including 973 taxa that are not in the 2002 IUCN Red List and that urgently need to be assessed for degree of threat status.
Noticeably absent from the species outcomes are reptiles, freshwater fish and nearly all the invertebrates. None of the reptiles or fish within this hotspot is currently on the IUCN Red List. This is a result of either (1) a lack of information on these species or simply (2) because nobody has yet made the required "assessment" for possible inclusion in the Red List. Among invertebrates, information was only available for gastropods. It is expected that many more invertebrate species (as well as plants and reptiles) will prove to be threatened once they are assessed using updated IUCN criteria. A list of potentially threatened dragonflies has also been compiled by Viola Clausnitzer of the University of Marburg, Germany.
Table 2 lists the 24 Critically Endangered species in this hotspot (five mammals, three birds, four amphibians, three gastropods and nine plants). Of these 24 species, 12 occur in Tanzania, seven in Kenya and five in both Kenya and Tanzania. If extinctions are to be avoided, the full set of these Critically Endangered species, together with the sites they depend on, must be ranked high among any priorities for conservation action. For example, 17 of the 24 Critically Endangered species in this hotspot are each restricted to a single site. This result is important for the site prioritization process.
There are other species in the hotspot, currently listed as Endangered, which should be re-assessed for threat status. These include the Zanzibar red colobus monkey (Procolobus kirkii) (less than 2,000, mostly in Jozani Forest Reserve) and Aders' duiker (probably less than 800 in a very restricted range with a 50 percent decline within last 15-20 years) (Struhsaker pers. comm.). Two other Endangered species—African Elephant and African Wild Dog—were identified as "landscape species," indicating that they will likely not be conserved through a site-based approach alone.
The definition of site outcomes produced 160 Key Biodiversity Areas for the Eastern Arc Mountains and Coastal Forests hotspot (Appendix 2, Table 3). Among these, 41 sites are important for mammals, 29 for birds, 19 for amphibians, four for gastropods and 140 for plants. In the hotspot, 26 sites are home to 10 or more globally threatened species, 53 sites have two to nine globally threatened species and 73 are important for at least one globally threatened species among the considered taxonomic groups. Nine more sites are included in Appendix 2, not because they host globally threatened species, but because they are IBAs with restricted-range bird species and globally significant congregations of birds. The full description of site outcomes and the species that occur in them is presented in Appendix 3. Figure 3 shows the location and distribution of the site outcomes in Kenya and Tanzania. The sites were overlaid with other existing geographical information including national boundaries, protected areas, rivers and topography to show their distribution in relation to other features.
Further analysis of the composition of the site outcomes (Appendix 2 and 3) indicates that 51 of the 160 sites are IBAs (Bennun & Njoroge 1999; Baker & Baker 2002). Some sites have high numbers of threatened species. These sites include: East Usambara Mountains, Uluguru Mountains, Udzungwa Mountains National Park, West Usambara Mountains, Udzungwa Mountains, Shimba Hills, Lindi District Coastal Forests, Nguru Mountains, Taita Hills, South Pare Mountains and Kisarawe District Coastal Forests. When the sites are ranked according to the number of threatened species that they contain, 23 of the top 25 sites are IBAs. This suggests that the IBA process succeeds in identifying the key sites for conserving species of global concern, at least on a broad scale.
An alternative to a simple threatened species richness ranking is to examine the site data for complementarity and to determine: 1) the minimum set of sites that contain all globally threatened species at least once; and 2) those sites that contain a species that occurs nowhere else (i.e. are irreplaceable, even if they only have one species). A preliminary analysis (Rodrigues and Langhammer pers. comm.) indicates that the minimum set consists of 35 sites and that, of these, 26 are irreplaceable. If the sites are ranked by species richness, the top 33 sites contain 97 percent of all threatened species (although it takes 129 sites to capture 100 percent). This means that, except for a few species, the selection of sites by a simple threatened species richness ranking is not a bad prioritization strategy compared with the complementarity set. Among the top 20 sites by species richness, only two (Bagomoya District Forests and North Pare Mountains) fail to make it into the complementarity set and only three are not irreplaceable (Bagomoya District Forests, North Pare Mountains and Mafia Island).
It must be understood, however, that neither strategy should be applied exclusively. There are many reasons for this. First, the survival of a threatened species is likely to require conservation interventions at more than one site. For example, the best known population of Clarke's weaver is in Arabuko-Sokoke Forest, but it doesn't breed there. Second, a species found in several sites may only have viable populations in one or two of them and these critical sites may not be captured by complementarity, or rank highly for species richness. Third, variation in the raw data (numbers of threatened species per site) can be partly accounted for by large site differences in area (over five orders of magnitude: Appendix 3) and/or research investment. Fourth, the outcome analysis is based on a small number of taxonomic groups and in some of these groups (especially the plants) the Red Lists are in serious need of re-assessment. Fifth, prioritizing sites must take into account not only their relative biological importance, but also the degrees of threat to them and the current investments in them.
With this background, there is no present justification for the exclusion of any of the 160 site outcomes from possible CEPF funding. Conversely, it would be a waste of the available data not to recognize that some particularly important sites should be targeted. A mixed strategy for site prioritization is therefore recommended.
CEPF investments cannot achieve all of the conservation outcomes identified in this profile, but, by defining these outcomes on the basis of globally threatened species, CEPF can ensure that all its projects in this hotspot will be targeted toward globally significant biodiversity conservation. The outcome definition also means that CEPF and other donors, as well as conservation organizations in general, can track the success of their investments and interventions, by measuring extinctions avoided and sites protected. This is particularly important for a global program like CEPF, which has a responsibility to use resources in ways that achieve biodiversity conservation most effectively at a global scale.
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