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Ecosystem Profile: Polynesia-Micronesia

Biological Importance of the Hotspot
The geographic complexity and isolated nature of Pacific islands have led to the development of extremely high levels of endemism in this hotspot. The various mechanisms of island biogeography and evolution have been able to work particularly clearly in the Pacific free of continental influences (Dahl 1986). However, the extreme vulnerability of island ecosystems and species to impacts such as habitat destruction and invasive species has resulted in the flora and fauna of this hotspot being amongst the most endangered in the world. In fact, species extinction rates in this hotspot approach the highest in the world, especially for birds (Steadman 1995) and land snails (Cowie 2001).

The present distribution of flora and fauna across the Pacific has resulted from the complex interplay of many factors in both time and space (Dahl 1984, Stoddart 1992). Endemism is a product of isolation, marginal environments, chance dispersal events like storms, and time (SPREP 1992). One of the key factors is the distance of an island from the major centers of evolution and distribution, such as Southeast Asia, the Indo-Malay Peninsula, Australia or America (MacArthur and Wilson 1967, Dahl 1980). The closer an island is to a center of evolution, the greater the opportunity that species from that area will have been able to colonize it (Dahl 1980). Other factors influencing Pacific biogeography are island size, type and precipitation (Mueller-Dombois 2002) and deep-sea trenches, such as the Tonga trench (Stoddart 1992).

The origins of most Pacific biodiversity are in Southeast Asia and New Guinea with a general attenuation in marine and terrestrial biodiversity from west to east. Thus there are no native amphibians east of Fiji and there are no native terrestrial mammals east of the Cook Islands, except for a single Hawaiian sub-species (a bat which originated from the Americas). The eastward diminution of biodiversity reflects several factors. The filtering effect of the ocean would be expected to filter out species that are not adept at crossing ocean gaps. Furthermore, island size and rainfall generally decrease eastwards and the greatest complexity of island types occurs in the west with continental islands not occurring east of Fiji (SPREP 1992). Last but not least, humans, who played a major role in the dispersal of species into the Pacific, migrated predominately from west to east (SPREP 1992).

Biodiversity of the Hotspot
In this section a brief summary of the terrestrial biodiversity of the hotspot is provided. The focus here is on hotspot biogeography and endemic species. In the subsequent section on ecosystems the emphasis is on the habitats, specifically on the biomes and ecosystems, of Pacific islands. In the later chapter on conservation outcomes, the focus is on the globally threatened species listed in the IUCN Red List (IUCN 2003) at the time of the expert roundtabes.

Plant, bird, and invertebrate diversity in the hotspot are particularly high, but diversity of non-volant mammals, reptiles, and amphibians is low. Overall the hotspot is home to approximately 5,330 native vascular plant species (Allison and Eldredge 2004), of which 3,070 (58 percent) are endemic, 242 breeding native bird species of which approximately 164 (68 percent) are endemic, 61 native terrestrial reptiles, of which 30 (49 percent) are endemic, 15 native mammals, all bats, 11 (73 percent) of which are endemic, and three native amphibians, all endemic (Allison and Eldredge 2004). Although there are no true native freshwater fish, at least 96 marine species are found as adults in freshwater and 20 species are endemic (ibid). Knowledge of invertebrate diversity is very patchy, but for many groups that have been studied, it is high. Land snail diversity is particularly high with over 750 species in Hawaii alone (Cowie 1996) and perhaps 4,000 species in the insular tropical Pacific (Cowie 2000). A summary of the number of known native and endemic species by political units for each taxonomic group is shown in Table 2 and a description of the distribution of each group follows.

In the Pacific the islands that tend to have the largest and most varied biodiversity are the bigger, higher, older, volcanic and western-most islands close to land masses of continental origin. Such islands have a far greater range of habitats and niches for colonization and speciation than the low coral islands. Similarly, elevated atolls have higher biodiversity than reef islands just at sea level (Dahl 1980). However, although the more isolated oceanic islands may have fewer biological groups, those that managed to colonize such islands may have undergone intense speciation to form many new species (SPREP 1992). The Hawaiian islands, for example, are one of the most isolated island groups in the world and have no native amphibians and no endemic reptiles but do have very high rates of endemism for some taxonomic groups, approaching 98 percent for land snails and 83 percent for vascular plants.

The diversity of most taxonomic groups follows the general pattern already described for biodiversity in the hotspot as a whole. Plant diversity is highest on the larger and higher volcanic archipelagos such as Hawaii, Fiji and Samoa. These three island groups, along with the Marquesas islands, have been identified by WWF/IUCN as Centers of Plant Diversity in the hotspot (van Royen and Davis 1995). Such centers are areas with high plant diversity (although the actual number of species present may not be accurately known) and high plant endemicity (ibid).

Although bird diversity is not very high by global standards, endemism is very high (Allison and Eldredge 1999) as are the numbers of globally threatened birds (Stattersfield et al 1998). Threats to bird species are not a new phenomenon in the Pacific. In fact, the Pacific islands are believed to have had more than 2,000 bird extinctions since human colonization (Steadman 1995). The highest diversity and endemism is in Hawaii, Fiji and French Polynesia. There are a total of 15 Endemic Bird Areas (EBAs), as defined by BirdLife International (Stattersfield et al 1998) in the hotspot. These are as follows, with the number of restricted range species in each EBA in brackets.

  • In Polynesia : Hawaii (15), Central Hawaiian islands (23), Laysan island (2), Samoan islands (20), Southern Cook islands (7), Rimatara (2), Marquesas islands (10), Society islands (8), Tuamotu archipelago (8), Henderson Island (4), and Fiji (27).
  • In Micronesia: the Mariana islands (12), Palau (16), Yap (7), and East Caroline islands (18).

Terrestrial reptile, mammal, and amphibian diversity in the hotspot are all quite low but endemicity is high. None of these groups are very vagile, especially at dispersing across large ocean gaps. The greatest diversity of all three groups is in the west and north of the region close to the biological source area (for most of the groups) of Southeast Asia. Of the 61 native terrestrial reptiles, Fiji and Palau have the greatest diversity. The terrestrial species include seven species of snakes and 53 species of lizards, mostly skinks and geckos but also two iguanas that are endemic to the Fiji-Tonga area (Allison and Eldredge 2004). Amphibian diversity in the hotspot is extremely low with only three native amphibians known to occur, all three endemic ranid frogs of the genus Platymantis (ibid). Two of the species are endemic to Fiji, the third to Palau and all three are believed to be related to species found in the Solomons and Papua New Guinea respectively (Allison and Eldredge 1999).

There are only 15 native terrestrial mammals in the hotspot and all are bats (Allison and Eldredge 2004). Eleven species, or 56 percent of the bats, are endemic, all fruit bats (ibid). Most of the bats are found on the high islands in the north and west of the hotspot, and all, bar the single Hawaiian sub-species, Lasiurus cinereus semotus, are related to Indo-Pacific groups. None of the rat species, which inhabit most of the islands in the hotspot, are believed to be native; all are assumed to have been introduced by the early inhabitants, or by Europeans (Allison and Eldredge 1999)

Invertebrates have been poorly studied globally despite the fact that invertebrates make up 99 percent of all animal species (Lydeard et al In Press). This is also true of the Polynesia-Micronesia Hotspot, where very few invertebrate groups, such as the land snails, have been studied comprehensively. Globally, the greatest snail diversity and endemism appears to be in isolated environments such as islands and in mountains (WCMC 1992). This is certainly true in the Pacific where land snail diversity is particularly high – approaching 4,000 species (Cowie 2000). In the hotspot, the greatest land snail diversity is on certain extremely isolated islands such as Rapa, Oahu and Mangareva (Cowie 1996). Pacific land snails are dominated by a relatively small number of families including the endemic Partulidae, Achatinellidae, Amastridae, and Endodontidae and the nonendemic Charopidae, Pupillidae, Helicinidae, Helicarionidae, and Succinidae.

Although this ecosystem profile focuses on terrestrial biodiversity, no summary of the biodiversity of an essentially oceanic region such as Polynesia and Micronesia could be complete without a brief description of the marine biodiversity. The Western Pacific has the highest marine diversity in the world, with up to 3,000 species being recorded from a single reef (SPREP 1992). Overall, the Pacific region has the most extensive coral reef system in the world, the largest tuna fishery, and the healthiest remaining global populations of many marine species such as whales and sea turtles (UNESCO 2003a). Unlike the relatively depauperate terrestrial mammal fauna, the marine mammal fauna of the region is quite rich (Allison and Eldredge 1999). As with the terrestrial realm there is a gradient of decreasing numbers of species from west to east, but there is a second gradient from warm equatorial waters to more temperate waters away from the equator as well (Dahl 1984). There is evidence that widely distributed species are a larger component of marine, rather than terrestrial, flora and fauna (ibid).

There have been a number of attempts to classify and map the ecosystems of the Pacific region, but none specifically for the hotspot. In 1974 IUCN classified and mapped the Pacific into 19 terrestrial biogeographical provinces based on island type, climate, and vegetation affinities. Dahl (1980) later modified the classification to 20 biogeographical provinces (terrestrial and marine) and classified the region into biomes and thence into 74 ecosystems, including about 27 terrestrial ecosystems, 12 freshwater ecosystems, and 35 marine ecosystems (ibid). Terrestrial biomes were distinguished according to vegetation type, while for the marine biomes, the substrate, as well as the dominant plant or benthic animals, was used to determine the classification.

The natural vegetation of the Pacific islands has been recently refined into 12 principal biomes (Mueller-Dombois and Fosberg 1998). Along the shores of most Pacific islands is salt and wind tolerant strand vegetation composed of herbs, vines and low shrubs. Fringing some sheltered shores, often where there is some freshwater source, are mangrove swamps composed of shrubs and trees. In inland areas on large, wet islands are various types of rain forest with a rich and diverse floristic composition of epiphytes, shrubs and trees. The natural vegetation at low elevations is coastal and lowland rain forest, although this has been eliminated on most islands in the hotspot. At higher elevations the rainforest changes to a lower stature, shrub and epiphyte-rich montane rainforest. At or above the cloud line on the highest islands are dwarf statured cloud forests. Above the cloud line on Hawaii and Maui the vegetation is a montane grassland or savanna mixed with xerophytic shrubs and trees while on the dry leeward slopes of some Hawaiian and Fijian islands is a mesophytic, or seasonally dry, evergreen forest composed of grasses and sclerophyllous shrubs and trees (ibid).

Wetlands have not been well studied in the Pacific, except in Hawaii and current and former U.S. territories (Scott 1993). However, some general statements can be made. On the whole, the atoll states have few, if any, significant wetlands other than reef systems. On the larger volcanic islands in the hotspot there are significant areas of wetlands of two main types, intertidal mangrove forests, and freshwater lakes, marshes, swamps and rivers. Fiji in particular has a diverse variety of inland wetlands including distinct sago swamps, peat bogs and pandanus savannas. Large mangrove forests are still found in coastal areas of Fiji, the Federated States of Micronesia (FSM) and Palau and to a lesser extent Tonga and Samoa. Mangrove forests are particularly important for fish, invertebrate and avian diversity, including a number of threatened migratory shorebirds. Freshwater wetlands such as coastal marshes, upland swamps and marshes, crater lakes and rivers cover a very small area overall but have unusual and poorly known floras and fish and invertebrate faunas. Many wetlands in the hotspot are threatened by development, pollution, invasive species and habitat conversion.

After centuries of human impact, the dominant vegetation types on most islands are now human induced or anthropogenic plant associations ranging from agroforests and secondary forest to grassland and savanna. It is estimated that more than three quarters of the original vegetation of the hotspot has been damaged or destroyed (Allison and Eldredge 1999). The forested area varies significantly from country to country in the hotspot but tends to be highest on the volcanic islands such as Fiji, Palau, and Samoa with 30-60 percent forest cover and lowest on the low islands and atolls from 5-40 percent forest cover (FAO 2003).

Recent assessments of globally significant ecosystems have identified a number of critical ecosystems or ecoregions in the hotspot. This could be interpreted as a strong endorsement of the choice of the hotspot by other environmental organizations. As mentioned, the hotspot includes four centers of plant diversity (van Royen and Davis 1995). Twenty two of the 867 global terrestrial ecoregions identified and mapped by WWF are in the hotspot, including all of the island groups in the hotspot (Olson et al 2001). Pacific terrestrial ecoregions have recently been revised slightly to take into account the latest information on invertebrate distribution (Olson pers. comm. 2003).

Many of the ecoregions mapped by WWF correspond closely to the biogeographic provinces of Dahl (1980). The main ecosystem represented in these ecoregions is tropical rain forests. However, included in the 22 ecoregions are a few occurrences of tropical dry forests in Hawaii, Fiji and Micronesia and shrublands and scrub in Hawaii. WWF’s Global 200 list of the most outstanding examples of the world’s ecosystems includes three terrestrial ecoregions in the hotspot, namely Hawaii’s rain forests, Hawaii’s dry forests and the South Pacific island forests which includes the rain forests of the Cook islands, Fiji, Tuamotus, Tonga, Society islands, Samoa, Marquesas, and Tubuai (Olson and Dinerstein 1998).

Assessments of global marine ecosystem diversity have identified a number of sites of global significance in the Pacific. WWF’s Global 200 list includes five outstanding coral ecoregions in the hotspot, namely Palau, Tahiti, Hawaii, Rapa Nui (Easter island), and Fiji (Olson and Dinerstein 1998). Conservation International has identified 18 global marine centers of endemism based on the number of restricted range reef fish, corals, snails and lobsters (Roberts et al 2002). There are two such centers in the Polynesia- Micronesia Hotspot, namely the Hawaiian Islands and Easter Island.

A number of ecosystems and habitats in the hotspot have been identified as having national or even international significance and have been declared as protected areas- including national parks, reserves, and conservation areas. These sites are discussed in the next section.

Level of Protection
A protected area is defined by IUCN-The World Conservation Union (IUCN 2004a) as, “an area of land and/or sea especially dedicated to the protection and maintenance of biological diversity, and of natural and associated cultural resources, and managed through legal or other effective means.” This definition encompasses government managed strict nature reserves through to areas managed by customary landowners for conservation and resource management.

There are at least 356 protected areas recorded within the hotspot covering approximately 1,872,196 hectares (18,722 square kilometers) of land and sea, however almost one-third of these are found in Hawaii alone. Excluding Hawaii, 154 of the hotspot’s protected areas (60 percent) are terrestrial, covering an area of approximately 199,750 hectares (1,998 square kilometers) or 6.7 percent of the land area of the hotspot. Table 3 summarizes the known protected area coverage in hotspot political units.

General assumptions on the effectiveness (i.e. representativeness and functionality) of the coverage of protected areas within the hotspot are subjective. Almost 40 percent of the protected areas listed in the Pacific Protected Area Database developed by Conservation International, have no recorded size. This may be because many of these areas have not been delineated. This deficiency in the data has meant that the size estimates for each country and the whole hotspot are skewed and extremely misleading. For example, 17 of Fiji’s 38 listed terrestrial protected areas have no size estimates. In general, where the land area covered by a protected area is defined, it is a general estimate or a contested figure. In addition, many of the areas listed are coastal areas with a terrestrial and marine component. There is often no clear distinction between the individual size of each (marine and terrestrial). Therefore, the summarized area listed in Table 3 may incorporate the marine component of a protected area in addition to the terrestrial component.

Table 3. Summary of Protected Areas by Political Units in the Polynesia-Micronesia Hotspot

Hotspot Country, State or Territory No. of Protected Areas Total Area Protected (marine & land) Terrestrial Protected Areas Land Area Protected (ha)
MICRONESIA 107 398,825 56 84,795
CNMI 12 2,323 8 2,318
FSM 32 9,895 10 9,425
Guam 16 14,844 10 4,933
Kiribati 14 112,542 14 64,542
Marshall Islands 7 70,100 5 1,126
Nauru - - - -
Palau 22 134,927 8 1,067
US Minor Islands 4 54,194 1 1,384
FIJI 65 77,641 38 39,641
POLYNESIA 184 1,395,730 165 384,814
American Samoa 13 5,692 11 3,959
Cook Islands 15 5,027 12 3,670
Easter Island 1 6,700 1 6,700
French Polynesia 9 23,030 8 19,710
Hawaii - - 105 309,500
Niue 3 6,057 2 6,029
Pitcairn Islands 1 3,730 1 3,730
Samoa 14 20,874 11 11,852
Tokelau 3 1,000 - -
Tonga 16 1,010,791 11 19,634
Tuvalu 2 3,300 1 -
Wallis and Futuna 2 30 2 30
TOTAL HOTSPOT 356 1,872,196 259 509,250

Note: The data in this table represent available information for each country, state, and territory at the time of compilation. The accuracy of the data is unknown at this stage and may be inaccurate and not necessarily representative of actual area protected. The information should therefore be treated with caution and should not be used as a guide to compare country coverage or to assess general protected area coverage within the hotspot.
Source: Conservation International’s “Pacific Protected Area Database” except data for Hawaii, which is from SPREP (1999).
- no data available

The lack of information regarding size, boundaries and, in many cases, even location information, in part reflects the unique nature of customary land tenure and resource rights within the Pacific region. Information identifying a protected area that is locally owned, used, and managed may encompass sensitive local and or traditional knowledge that the land and resource owners do not want revealed or publicized. In addition, most countries do not have a centralized up-to-date record of their protected areas due to limited government resources and capacity, and lack of national coordination between bodies responsible for protected areas.

When considering protected area coverage for the region it is important to recognize that many Pacific “protected areas” are not dedicated primarily for the purposes of biodiversity conservation. Many are areas that have been established for utilitarian purposes of resource management as well as the maintenance of ecological systems for continued sustainable use. The conservation of biodiversity may occur but it is not the primary objective of these areas.

Traditional Closures

Pacific island communities have traditional systems of “setting areas aside.” These areas form part of the community’s culture, customs, and traditional resource management practices and include areas such as “mo” areas in the Marshall Islands, “ra’ui” areas in the Cook Islands, and “tabu” areas in Fiji. These areas may be temporary closure areas such as Pouara Ra’ui in the Cook Islands, closed for two years, or permanent closure areas. National governments often do not recognize these traditional conservation and resource management arrangements. The Pacific Protected Area Database only encompasses permanent protected areas where they are publicly known. Subsequently many traditionally protected areas are not listed in the Database or included in Table 3. These areas play a vital role in the conservation effort within the hotspot and should not be overlooked.

Protected Area Classification
Protected areas are dedicated and managed for a variety of purposes including scientific research, wilderness protection, preservation of species and genetic diversity, maintenance of environmental services, protection of specific natural and cultural features, tourism and recreation, education, sustainable use of resources from natural ecosystems, and maintenance of cultural and traditional attributes (IUCN 2004a). IUCN developed six protected area management categories, illustrating the range of purposes and objectives protected areas can serve. The classification system provides a rationale for why the protected area was established. Increasingly along the continuum (from Ia – VI), emphasis is placed on direct human use and resource development.

Each country, state, and territory has an individual protected area categorization system, often outlined in the National Biodiversity Strategy and Action Plans, where these exist. These national interpretations exist in addition to the IUCN system. The difficulty in standardization lies in the different, and at times inaccurate, interpretations of the IUCN Classification system between countries and organizations. Some protected area sites have been allocated more than one category by different sources; the same site may be listed as a category II (National Park) in one source and as a category IV (Managed Resource Protected Areas) in another source. This may be due to the various interpretations of the classification system and to the multiple use nature of many protected areas and the different zones of management within many sites.

A number of sites in the hotspot have been identified as internationally significant and have been declared either World Heritage sites, Biosphere reserves, or Wetlands of International Importance (Ramsar sites). Three areas have been declared by the United Nations Educational, Scientific and Cultural Organization (UNESCO) as World Heritage sites for their globally significant cultural and or natural heritage. The Hawaii Volcanoes National Park was declared a World Heritage site in 1988 for its unique geology, including one of the most active volcanoes in the world. Rapa Nui National Park on Easter island was inscribed in 1995 for its unique cultural heritage and monumental basalt figures called moai. Henderson island in the Pitcairn group was inscribed in 1988 due to its pristine environment and large number of endemic terrestrial species. Many of the islands in the Central Pacific, including the Line islands and a number of reefs and islands in three countries, have been proposed as a combined World Heritage Site for their relatively intact and undisturbed natural communities with significant marine and avian biodiversity. Other sites in the hotspot, including sites in Fiji and a proposed Samoan Archipelago site, are also being assessed.

There are two Man and the Biosphere reserves in the hotspot, selected by UNESCO for their outstanding biological values and potential for scientific research. These two sites are the Atoll de Taiaro in the Tuamotu group of French Polynesia - declared in 1977 due to its pristine and unusual atoll environment, with a completely enclosed inner lagoon, and the Hawaii Islands Biosphere Reserve - declared in 1980 for the unique, highly endemic and threatened biodiversity of the Hawaiian islands. Only one site in the hotspot has been declared a Ramsar wetland site- Lake Ngardok, on Palau, dedicated in 2002. This 493 ha site has significant fish and avian fauna, including the national bird of Palau, the Palau fruit dove or “biib” (Ptilinopus pelewensis). Other sites in the hotspot have been nominated as Ramsar sites, including Lake Lanoto’o in Samoa, but have not yet been dedicated.

Many of the protected areas within the hotspot are managed for sustainable use of natural ecosystems (Category VI) but have small traditional closed (no-take) areas within them. This category is generally more appropriate within Polynesia and Micronesia because of the predominance of customary land ownership and the economic, social, cultural, and spiritual connection and dependence land and resource users have with their environment.

The regional trend for networks of small locally managed areas particularly in the marine sector should be noted. Small-scale protected areas linked by networks and supported by external organizations (NGO, private, or government) are considered more socially appropriate, financially feasible and managerially sustainable within the Pacific region. The Locally Managed Marine Area Network in the Western Pacific provides a good working example of this approach.

A variety of protected area models and governance arrangements occur within the hotspot. Most countries within the hotspot now have a centralized system of land and resource management, in line with western approaches to governance. Commonly these systems of governance have often been superimposed onto existing customary structures. Due to the unwritten nature of customary tenure and law, this has occurred in some nations relatively quickly. However, there is now a renewed emphasis on people-oriented conservation initiatives within the region such as community-based conservation areas (CBCAs) and co-managed protected areas. These governance structures can cover the full plethora of protected area categories and encompass a wide range of stakeholders and support including private, NGO, and government. National governments often have limited knowledge, involvement, and jurisdiction over community conservation areas. Despite this, national governments are generally the primary body responsible for reporting on the protected area status of their countries.

In recognition of the great diversity of protected area governance types and the influence these have on the management of a protected area, a typology of protected area governance was recently added as an extra dimension to the IUCN protected area categories. This was an outcome of the 2003 Vth World Parks Congress in Durban, South Africa. A protected area will therefore be any combination of the four types of PA Governance and six IUCN management objective categories. This new dimension of classification will be invaluable when considering the conservation status of the Polynesia-Micronesia Hotspot in the future.

Community Conserved Areas
The status and management effectiveness of most of the protected areas summarized in Table 3 is unknown at this stage. Some general conclusions can however be made. The listed protected areas for the hotspot are poorly resourced with limited management support and capacity. The practice of conservation through conventional forms of protected areas throughout the Pacific islands region appears to have been largely ineffective, having historically been applied without due respect for customary land and resource tenure arrangements or traditional practices and rights. Consequently, the hotspot does not have an effective developed protected area system in the formal “western” sense.

There is new awareness of traditional approaches to conservation. The now more formalised community conserved areas must be considered when assessing protected area coverage. These areas have played, and will continue to play, a fundamental role in the conservation of biodiversity within the Polynesia-Micronesia Hotspot. In general, due to land tenure arrangements and customary resource rights, it appears that co-managed protected areas between communities and state or NGOs, and community conservation with government or NGO support, are the most appropriate governance models for protected areas in the hotspot.

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