Biological diversity in the East Melanesian Islands
Contents
Overview Map of the East Melanesian Islands. (Source: CI (Biological diversity in the East Melanesian Islands) /CABS)
The East Melanesian Islands Hotspot lies northeast and east of New Guinea and includes the Bismarck and Admiralty Islands, the Solomon Islands, and the islands of Vanuatu. Politically, this includes parts of Papua New Guinea (including the islands of New Britain, New Ireland, Manus and Bougainville), and all of the Solomon Islands and Vanuatu. In total, this hotspot includes some 1,600 islands, encompassing a land area of nearly 100,000 km2 more than double that of the Polynesia-Micronesia Hotspot.
The region is one of the most geographically complex areas on Earth, with a diverse range of islands of varying age and development. The two main islands of the Bismarck Archipelago, New Ireland and New Britain, are mountainous, with peaks exceeding 2,000 meters. Several of the smaller islands in the archipelago are recent volcanoes, some still active. Bougainville, the largest island in the Solomon chain, has several high massifs (some volcanic), including Mount Balbi, which, at 2,685 meters above sea level, is the highest point in the hotspot.
The Solomon Islands have been severely impacted by logging, copra plantations, and the introduction of exotic species like cats and rats. (Source: © Wolcott Henry) Habitats in the hotspot include coastal vegetation, mangrove forests, freshwater swamp forests, lowland rainforests, seasonally dry forests and grasslands, and montane rainforests. Most of the habitats are species poor by comparison to New Guinea, though rich when compared to Polynesia-Micronesia, with several tree species dominating (such as those in the genera Terminalia, Pometia, Agathis and Metrosideros).
Unique and Threatened Biodiversity
Because most of the islands of this hotspot have never been in land contact with New Guinea, their fauna and flora are a mix of recent long-distance immigrants and indigenous lineages derived from ancient Pacific-Gondwanaland species.
Thus, the hotspot contains classic examples of relatively recent adaptive radiation typical of oceanic islands, such as the white-eyes (family Zosteropidae) and monarch flycatchers (family Monarchidae), but also carries some odd colonizers from times past such as the giant prehensile-tailed skink (Corucia zebrata), whose closest living relatives are the blue-tongued skinks (genus Tiliqua) of Australia, New Guinea, and Indonesia. The East Melanesian Islands Hotspot also has affinities with Fiji (included as part of the Polynesia-Micronesia Hotspot), such as the Platymantis frogs, ancient “monkey-faced” fruit bats of the genus Pteralopex, and Nesoclopeus rails. Interestingly, while a number of species found in New Guinea also occur in this hotspot, certain groups that are prominent on mainland New Guinea are notably absent from the region. These include birds of paradise, bowerbirds, scrub-wrens, tree kangaroos, echidnas and gliders.
The isolation of many of the islands and local adaptive radiation have led to very high levels of endemism, with numerous species endemic to the hotspot and many others endemic to subsets of the hotspot or even confined to single islands.
Plants
There are an estimated 8,000 species of vascular plants in the East Melanesian Islands, about half of which are thought to be endemic to the region. The rainforests of these islands look much like those found on New Guinea, and many of the same common forest trees dominate these forests. However, a number of tree species are conspicuously absent, including the Dipterocarpaceae, which dominate in Southeast Asia and are common in a few places in New Guinea. The largest and most remarkable of the hotspot’s trees is the Kauri pine (Agathis spp.), a conifer that grows to a huge girth and is highly prized by foresters.
Vertebrates
Birds
The avifauna of East Melanesia is compositionally more distinct from New Guinea than are the other vertebrate groups, and includes seven endemic genera. Overall, the hotspot is home to more than 360 regularly occurring bird species, more than 40 percent of which are endemic. The region encompasses six Endemic Bird Areas (EBAs), as defined by BirdLife International, including the Solomon group, which has more than 60 endemic species.
The claret-breasted fruit-dove (Ptilinopus viridis) is one of more than 350 bird species that inhabit East Melanesian Islands Hotspot. (Source: © John Pilgrim) One of the hotspot’s most beautiful birds, and one of the most difficult to see, is the black-faced pitta (Pitta anerythra, VU). The fearful owl (Nesasio solomonenis, VU), a Solomon Islands endemic, is the hotspot’s largest nightbird. The most majestic avian flagship is Sanford’s fish-eagle (Haliaeetus sanfordi, VU), which favors coastal forests, although pairs also hunt further inland and, at least on the eastern islands, appear to have entirely inland ranges where they prey largely on northern common cuscus (Phalanger orientalis) and fruit bats.
Mammals
Nearly half of the region’s more than 85 mammal species are endemic. The richest diversity of mammals in East Melanesia is among the bats (Chiroptera), which account for more than three-quarters of the hotspot’s mammals, including three endemic genera (one of which is represented by a single species, the flower-faced bat, Anthops ornatus, VU).
The most remarkable of the bats are the flying foxes (Pteropodidae), which play an important role in pollination and seed dispersal. Of more than a dozen threatened species of pteropodid bats in the hotspot, three are highly threatened (though poorly known). The Bougainville monkey-faced bat (Pteralopex anceps, CR) was known mainly from specimens collected in the 1920s, until six bats were observed during a 1995 survey (and apparently no sign of this bat was found during fieldwork on Choiseul in 1992 or on Buka in 1997); the montane monkey-faced bat (P. pulchra, CR) is known from only a single specimen collected on Mt. Makarakomburu on Guadalcanal; and the Guadalcanal monkey-faced bat (P. atrata, CR) was last recorded in 1991.
Besides the flying foxes, the admiralty cuscus (Spilocuscus kraemeri) is the only endemic cuscus in the hotspot, being confined to the Admiralty Islands. This beautifully patterned brown, black, and white species is a popular game animal on Manus.
Reptiles
For the most part, the East Melanesian Islands is one typified by skinks and geckos, and the majority of the hotspot’s more than 110 species of reptiles (nearly half of which are endemic) are members of the families Gekkonidae and Scincidae. The region also has six endemic genera of reptiles; five of these are each represented by a single species, including the large prehensile-tailed skink (Corucia zebrata), a lizard that lives in trees and feeds primarily on the leaves of epiphytes. It is interesting to note that both boas and pythons co-occur in this hotspot.
Amphibians
Roughly 90 percent of amphibian population in the East Melanesian Islands Hotspot are endemic. The Gunther’s triangle frog (Ceratobatrachus guentheri) is one example of the unique amphibian biodiversity. (Source: © John Pilgrim) Not surprisingly, given its isolation, the amphibian fauna of this hotspot is somewhat impoverished. More than 40 amphibian species are recorded from this hotspot, over 90 percent of which are endemic. There are also four endemic genera of amphibians, two of which have only one species: Palmatorappia solomonis (VU), a species from the Solomon Islands that may actually represent two species, and Ceratobatrachus guentheri, found on the Solomon Islands and Bougainville and Buka islands.
Freshwater Fishes
The small group of freshwater fishes that inhabits the region has been little studied to date. However, work is now beginning to document the region’s freshwater biota. It is estimated that there are more than 50 species of freshwater fishes in the hotspot, although only a handful are endemic, among them Stenogobius alleni, found on New Britain Island in Papua New Guinea, and Stiphodon astilbos, found in Vanuatu. Because the fishes inhabiting this hotspot are of marine origin, all freshwater fishes are capable of tolerating a wide range of saltwater concentrations.
Invertebrates
Little is known about the invertebrate fauna of the East Melanesian Islands. Butterflies are the best-known invertebrates in the hotspot, with a few species of Ornithoptera (birdwing) butterflies, particularly O. allotae and O. victoriae – both large, prominent and spectacular species – and the blue emperor swallowtail (Papilio ulysses) found in the Bismarcks and Solomons.
Human Impacts
Exploitation of fisheries is one of many problems facing the East Melanesian Islands Hotspot. (Source: © Wolcott Henry) The East Melanesian Islands hotspot holds exceptional cultural and linguistic diversity. Vanuatu, for example, has 109 living traditional languages, more per unit area than any other country. The Solomon Islands, with 74 languages, is only slightly less diverse. Because many languages are spoken by only a few hundred people, they are dying out or mixing into Pijin-Austronesian-Creoles, leading to a rapid loss of traditional knowledge and practice. Although this loss often leads to an erosion of traditional links between communities and the forests that have long served as their source of wealth and subsistence, it has been a shift to the modern cash economy, more than anything, that is the underlying force behind the rise in destructive exploitation of the region's natural environments.
In just the last three decades, rapid forest clearance and degradation has left only about 25 percent of the region's lowland forests in pristine, old growth condition. Such acceleration in habitat loss is the primary reason for the reclassification of this region from a wilderness area to a biodiversity hotspot. The remaining lowland forests are in the least accessible parts of the hotspot, especially where local communities have resisted foreign logging companies. While the upland humid forests are in better condition, population growth presents a serious threat to these forests, which are being cleared for subsistence agriculture.
The Bismarcks, Solomon Islands and Vanuatu have been most affected by extensive logging of lowland and hill forests and subsequent land clearing for copra and oil palm plantations, while the Admiralties have been most affected by agricultural expansion. Another major threat to the region is the impact of invasive alien species, especially pigs, cats (several species of giant rodents have been extirpated from Guadalcanal by cat predation), rats and little red fire ants (Wasmannia auropunctata), which have reached plague levels on many of the Solomon Islands.
Mining is a threat in a few localized areas of the region, including Bougainville and Lihir. Poor governance and government instability throughout the hotspot have led to inadequate management of resources, poor (and poorly managed) deals with international resource developers, such as mining and logging companies, and social and cultural disruption. For example, a nearly decade-long war on Bougainville was related to poor management of the large Panguna Copper Mine on the island, and the fact that local people suffered most of the costs of the mine yet reaped few benefits.
Conservation Action and Protected Areas
A waterfall in the interior of Guadalcanal, the largest island in the Solomons archipelago. Establishing clearly defined and appropriately protected wildlife areas has been a challenge in the East Melanesian Islands Hotspot. (Source: © Conservation International, photo by Todd Stevenson) Overall, protected area coverage in the East Melanesian Islands is almost non-existent. Although there are officially 24 protected areas covering six percent of the land area of the hotspot, only eight are currently classified in IUCN categories I-VI. These eight protected areas (none of which are in the higher protection categories) cover just one percent of the land.
Formal land protection is limited in the hotspot principally because the three nations respect local customary land tenure. Rather than legally codifying land ownership, these customs rely on a system of land dispute hearings to settle conflicting claims over land ownership or usage rights. Given the lack of clearly defined legal land title and widespread and severe rural poverty throughout the hotspot, the most common conservation strategy has been community-managed protection associated with community development activities.
International and local NGOs have played the main role in conservation in the region, often in partnership with government conservation agencies. The Secretariat for the Pacific Regional Environment Programme (SPREP), a multi-governmental conservation and environmental organization, works closely with member governments and has developed community-based conservation projects in the hotspot.
To highlight a few projects in the hotpot, The Nature Conservancy has worked in the Kimbe region of New Britain since 1994, collaborating with Mahonia na Dari to develop a network of locally managed marine protected areas, encouraging community-based conservation and resource management, and helping to establish a locally managed research and conservation center. The World Wide Fund for Nature has been working in partnership with a local group in Western Province, Solomon Islands, to develop a community resource conservation and development project on Tetepare Island, which is the largest uninhabited island in the South Pacific and is celebrated for its natural and archaeological value.
Conservation International and its partners have been active in parts of the region for more than a decade, resulting in the designation of the Klampun Wildlife Management Area (WMA) in 2003 (with the neighboring Tiemtop WMA, which is still in process of designation) in East New Britain. Work to establish a conservation area in the Bauro Highlands of Makira Island, in the Solomon Islands is also underway, with the aim of having the area collectively managed by landowning groups and recognized by the government. The Solomon Islands government has developed a community-based conservation project in Komaridi, on Guadalcanal in the Solomon Islands, leading to the creation of a local conservation area of lowland and montane rainforest. Unfortunately, the ecotoursim component of this project, supported by SPREP, was terminated in 2000 due to unrest and enthic tension in the region.
In Vanuatu, the New Zealand Royal Forest and Bird Protection Society, the Vanuatu Protected Areas Initiative and the Vanuatu Environment Unit have established a conservation project at Vatthe on Espiritu Santo, Vanuatu. The Vatthe project has focused on conservation of the largest tract of remaining lowland rainforest on Espiritu Santo by means of a community-based project.
Because of the current lack of large-scale conservation action in the East Melanesian Islands, the region is in urgent need of increased conservation attention and investment. Priorities are to address the difficulties of conservation on uncodified customary land, to develop successful and mutually beneficial partnerships with local communities, to address the threat of alien invasive species, and to promote the establishment of healthy and secure protected areas.
Further Reading
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- Bayliss-Smith, T., Hviding, E & Whitmore, T. 2003. Rainforest composition and histories of human disturbance in Solomon Islands. Ambio 32: 346-352.
- Bowen-Jones, E., Abrutat, D., Markham, B & Bowe, S. 1997. Flying foxes on Choiseul (Solomon Islands): The need for conservation action. Oryx 31:209-217.
- D'Abrera, B. 1990. Butterflies of the Australian Region. Melbourne: Hill House. ISBN: 0701803134.
- Flannery, T.F. 1995. Mammals of the South-West Pacific and Moluccan Islands. Chatswood, Australia: Reed and Australian Museum. ISBN: 0801431506.
- Foster, R.B. 2001. The Forest Vegetation of Southern New Ireland. In Beehler, B.M. & L.E. Alonso. (Eds.), Southern New Ireland, Papua New Guinea: A Biodiversity Assessment, RAP Bulletin of Biological Assessment 21. pp. 25-31. Washington, DC.: Conservation International. ISBN: 1881173615.
- Hansen, M.C., DeFries, R.S., Townshend, J.R.G., Carroll, M., Dimiceli, C., & Sohlberg, R.A.. 2003. Global Percent Tree Cover at a Spatial Resolution of 500 Meters: First Results of the MODIS Vegetation Continuous Fields Algorithm.
- Honza, E., Davies, H.L. Keene, J.B., & Tiffin, D.L. 1987. Plate boundaries and evolution of the Solomon Sea Region. Geo-Marine Letters 7:161-168.
- Johns, R.E. 1993. Biodiversity and conservation of the native flora of Papua New Guinea. In B. Beehler. (Ed.), A Biodiversity Analysis for Papua New Guinea. Conservation Needs Assessment, Vol. 2. pp. 15-76. Washington, DC.: Biodiversity Support Program.
- Mayr, E. & Diamond, J.M. 2001. The Birds of Northern Melanesia. Cambridge, Massachusetts: Harvard University Press. ISBN: 0195141709.
- McCoy, M. 1980. Reptiles of the Solomon Islands: Wau Ecology Institute Handbook No. 7. Wau, Papua New Guinea.
- Miller, S.E. 1996. Biogeography of Pacific insects and other terrestrial invertebrates: A status report. In A. Keast, & S.E. Miller. (Eds.), The Origin and Evolution of Pacific Island Biotas, New Guinea to Eastern Polynesia: Patterns and Processes. pp. 463-475. Amsterdam: SPB Academic Publishing.
- Mueller-Dombois, D. & Fosberg, F.R. 1998. Vegetation of the Tropical Pacific Islands. New York: Springer-Verlag. ISBN: 038798285X.
- Read, T. 2002. Navigating a New Course: Stories in Community-based Conservation in the Pacific Islands. New York: United Nations Development Program. ISBN: B0006S8HR4
- van Steenis, C.G. 1950. The delimitation of Malesia and its main plant geographical divisions. Flora Malesiana Series 1:70-75.
- Takhtajan, A. 1986. Floristic Regions of the World. Berkeley: University of California Press. ISBN: 0520040279.
- Thistlethwait, R. & Votaw, G. 1992. Environment and Development: A Pacific Island Perspective. Apia: Asian Development Bank, Manila and South Pacific Regional Environment Programme. ISBN: 9715610072.
- UNDP. 1999. Pacific Human Development Report 1999: Creating opportunities. Suva: UNDP. ISBN: 9823040125.
- Whitmore, T.C. 1975. Tropical Rain Forests of the Far East. Oxford: Clarendon Press. ISBN: 0198542410.
- Wikramanayake, E.D., Dinerstein, E., Loucks, C., Olson, D., Morrison, J., Lamoreux, J., McKnight, M., & Hedao, P. (Eds.). 2002. Terrestrial Ecoregions of the Indo-Pacific: A Conservation Assessment. Washington, D.C.: Island Press. ISBN: 1559639237.
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