Biological diversity in Wallacea

September 10, 2010, 8:53 am
Content Cover Image

The magnificent Sulawesi red-knobbed hornbill (Aceros cassidix) (Source: Lip Kee Yap)

caption Map of Wallacea. (Source: CI/ CABS)

The Wallacea hotspot encompasses the central islands of Indonesia east of Java, Bali, and Borneo, and west of the province of New Guinea, and the whole of Timor Leste. The hotspot, which occupies a total land area of 338,494 km2, includes the large island of Sulawesi and also the Moluccas, or Spice Islands, and the Lesser Sundas (which encompasses Timor Leste, and the Indonesia region of Nusa Tenggara).

Wallacea is divided from Sundaland, the other hotspot found in Indonesia, by Wallace's Line, which separates the Indo-Malayan and Australasian biogeographic realms. The line and the hotspot are both named for the 19th century English explorer and naturalist Alfred Russel Wallace, who identified the distinctiveness of faunas on either side of the line.

In terms of vegetation, Sulawesi and the Moluccas are largely tropical rainforest, but in many parts of the Lesser Sundas, rainforest formations are found only at high elevations and in areas facing the rain-bearing winds, while significant areas are covered in savanna woodland, including some Eucalyptus forests. In some lowland areas, such as in eastern Sulawesi, there are unusual and infertile ultrabasic soils with high concentrations of iron, magnesium, aluminum, and heavy metals. The lowland forests on these nutrient-poor ultrabasic soils have rather short trees, and appear to be dominated by the myrtle family.

Unique and Threatened Biodiversity

caption The magnificent Sulawesi red-knobbed hornbill (Aceros cassidix ) is endemic to Sulawesi island in the Wallacea Hotspot. (Source: Lip Kee Yap)

Wallacea has very high numbers of species found nowhere else in the world, in part because it is tropical and made up of many islands and in part because of its complex geological history. The land fragments of Wallacea separated from mainland Asia around 200 million years ago, contributing to their isolation and the evolution of many unique species. The hotspot lies between the Indo-Malayan and Australasian biogeographic realms and includes representatives from each of these regions as well as many endemics in its own right.

Plants

Although the flora of this island region is not well known, it is estimated that there are about 10,000 species of vascular plants, with roughly 1,500 endemic species (15 percent) and at least 12 endemic genera. There are about 500 endemic species on Sulawesi, 120 on the Lesser Sudas and 300 on the Moluccas.

The wetter lowland and hill forests have the highest number of tree species, but differ from the commercially valuable forests of Sundaland in having only a handful of dipterocarp species. The major trees of commercial value are the tall kauri (Agathis spp.), the magnificent yellow-flowered legume Pterocarpus indicus in the more seasonal areas, and the gum tree Eucalyptus deglupta, usually found in riverine habitats and used extensively in reforestation projects.

Vertebrates

Birds

The rainbow lorikeet (Trichoglossus haematodus weberi) is a subspecies endemic to Flores island in the Wallacea Hotspot. (Source: © Thomas Brooks)

There are about 650 regularly occurring bird species in Wallacea, and roughly 265 (40 percent) of these are endemic. There are also 29 endemic genera. Endemism is significant at the level of individual islands; Sulawesi has the largest fauna, with 356 species, including 96 endemics, among them the maleo (Macrocephalon maleo, EN), a distinctive megapode currently thought to number between 4,000 and 7,000 breeding pairs. These chicken-like birds build mounds in which they bury their eggs, and, three months later, the young explode out of the mound already feathered in adult plumage.

The maleo is but one of some 50 bird species threatened with extinction in this hotspot, including the caerulean paradise-flycatcher (Eutrichomyias rowleyi, CR), which was thought to be extinct until its rediscovery in 1998. The species is confined to remnant patches of forest at the base of Gunung Sahendaruman on Sangihe, north of Sulawesi, and is thought to number between 19 and 135 birds. Another species confined to Sangihe is the Sangihe white-eye (Zosterops nehrkorni, CR) known only from a single historical specimen, but for which there has been a spate of recent sightings around Gunung Sahenduraman.

As a testimony to the diversity and endemism of Wallacea, ten Endemic Bird Areas (EBAs) have been identified within the hotspot by BirdLife International.

Mammals

More than 125 of Wallacea's 220-plus mammal species are found nowhere else in the world. Only the Madagascar and Sundaland hotspots have a higher level of mammal endemism. If endemism is recalculated excluding the region's more than 125 species of bats (because they disperse easily), the level of mammal endemism is an astonishing 88 percent.

One of the most unusual mammals in Wallacea is the babirusa (Babyrousa babyrussa, VU). Babirusas (literally "pig-deer" in Bahasa-Indonesian) are pig-like animals characterized by the male's long recurved tusks that penetrate the upper lip. Two species of anoas, or dwarf buffaloes, are endemic to the forests of Sulawesi: the lowland anoa (Bubalus depressicornis, EN) and the mountain anoa (Bubalus quarlesi, EN).

There are a number of endemic primates in the hotspot. The island of Sulawesi is home to at least seven species of endemic macaques and at least five species of endemic tarsiers. Tarsiers are tiny, goggle-eyed creatures that resemble mammalian tree frogs more than monkeys.

Unfortunately, about one-third of endemic mammals in this hotspot are threatened with extinction. Besides the aforementioned babirusa and the anoas, this includes the Sulawesi palm civet (Macrogalidia musschenbroekii, VU), which as the name suggests is found only on Sulawesi in lowland and montane forests to 2,600 meters, and around 25 species of rodents.

Reptiles

The world's largest lizard, the Komodo dragon (Varanus komodoensis, VU), occurs only on the islands of Komodo, Padar, Rinca, and Flores in the Wallacea Hotspot. (Source: Ji?í Bukovský/BioLib/Encyclopedia of Life)

Wallacea's reptile species total more than 220 species, nearly 100 of which are confined to the hotspot. There are also three endemic genera, all snakes: Calamorhabdium, with two species, and Rabdion and Cyclotyphlops, both monotypic.

The best-known reptile species in Wallacea is the Komodo dragon (Varanus komodoensis, VU), the largest lizard in the world, with males that can grow up to 2.8 meters in length and weigh about 50 kilograms. The lizard is found only on the islands of Komodo, Padar, Rinca and Flores in the Lesser Sundas, the driest portion of Indonesia.

Only a single turtle species is found in this hotspot, the recently described McCord's sideneck turtle or Roti Island snake-necked turtle (Chelodina mccordi, CR). This species is the western-most occurring species of the family Chelidae, a dominant turtle group from Australia and New Guinea. This species occurs only in three separate populations on a single small island (Roti) with 70 km2 of available habitat.

Amphibians

Nearly 50 amphibian species, all frogs, are native to Wallacea; more than 30 of these are endemic, including the Sulawesi toad (Bufo celebensis) and Oreophryne monticola (EN). The latter is one of eight threatened species present in the hotspot; the remaining seven species are all endemic: Oreophryne celebensis (VU); O. variabilis (VU); Nyctimystes rueppelli (VU); Callulops kopsteini (EN); Limnonectes arathooni (EN); Limnonectes heinrichi (VU); and Limnonectes microtympanum (EN).

Freshwater Fishes

Nearly all of the more than 300 freshwater fish species found in Wallacea are tolerant of both fresh and saltwater. About 75 of these species are endemic to the hotspot. On the island of Sulawesi alone, there are nearly 70 known fish species, about three-quarters of which are endemic. The deep lakes, rapids, and rivers that make up the Malili Lakes in South Sulawesi have at least 15 endemic and quite beautiful telmatherinid fishes, two of them representing endemic genera, three endemic Oryzias, two endemic halfbeaks, and seven endemic gobies.

Invertebrates

Most of the invertebrate fauna of Wallacea remains poorly known, except for the enormous bird-wing butterflies, which are members of the swallowtail butterfly family. There are more than 80 species of birdwings in Wallacea, more than 40 of which are endemic. One species, Ornithoptera croesus (EN), which is endemic to the northern Moluccas, has a wingspan of nearly 20 centimeters in females. There are also 109 tiger beetles recorded from this hotspot, 79 of which are endemic. The northern Moluccas also contains the world's largest bee (Chalocodoma pluto) with females that can grow as large as four centimeters in length.

Human Impacts

A village on Sumbawa Island, central Indonesia. (Source: © Thomas Brooks)

Human populations have been clearing land by fire and other means for shifting agriculture and livestock grazing ever since they arrived in Wallacea about 40,000 years ago. Nevertheless, as elsewhere, Wallacea's ecosystems have been most dramatically impacted in the last 100 years or so. In the last century, the human population of the hotspot has quadrupled, and development has grown along with it. One of the world's newest countries, Timor Leste, was officially recognized in 2002, and many parts of Wallacea have seen political turmoil and dramatic changes.

Commercial logging began in Wallacea in the early 20th century. Forests have been cleared for agriculture, timber plantations, and land-settlement schemes, including the infamous transmigration program in which the Indonesian government moved people from densely populated islands to less populated ones. Furthermore, as has been so obvious with the El Nino-related fires that have raged through much of Indonesia from mid-1997 to the present, fire continues to be a problem, exacerbated by increased drying because of logging and plantation agriculture and sometimes intentional burning. Overall, 45 percent of Wallacea has some remaining forest cover, although only 15 percent is in more or less intact condition. The Lesser Sundas are thought to have only about seven percent forest cover remaining, while Sulawesi is still about 42 percent covered in original forest. Much of the forest that remains has been allocated to timber concessions or mining developments, and the growing population has increased the pressure from hunting and poaching.

Pressures on individual species are also exacerbated in this hotspot, because it is made up of islands, which are particularly vulnerable to extinctions. Sangihe, north of Sulawesi, has been almost completely devastated by human activity for coconut and nutmeg plantations. Today, the only remaining habitat is a small patch of montane forest on top of an extinct volcano (Gunung Sahendaruman), thought to be the last home of the caerulean paradise-flycatcher and Sangihe white-eye, and last known stronghold for the Sangihe shrike-thrush (Colluricincla sanghirensis, CR) and elegant sunbird (Aethopyga duyvenbodei, EN).

Conservation Action and Protected Areas

Boys and girls from the island of Sulawesi play music wearing traditional costumes. (Source: © Conservation International, photo by Russell Mittermeier)
 

The biodiversity in Wallacea varies so much from island to island that nearly every island needs its own protected areas to ensure the long-term conservation of endemic species. This need is particularly urgent in the Moluccas, where there are few protected areas. Only about 24,000 km2, seven percent of the original hotspot, is under some form of protection. As an example of the poor representation of biodiversity in the protected areas, only 35 of the 112 Important Bird Areas that have been identified by BirdLife Indonesia are currently protected.

The Wildlife Conservation Society recently carried out a three-year island-wide biodiversity survey on Sulawesi to understand key conservation issues and make recommendations to national, provincial and regional governments. Currently, the most important protected area on the island of Sulawesi is the 3,000-km2 Bogani Nani Wartabone Park, which was established in the 1980s as an integrated conservation and development project to protect the forests and the watershed in the area. However, the park is threatened by small-scale gold mining, illegal agricultural encroachment and illegal logging, hunting and rattan collection.

The 2,300-km2 Lore Lindu National Park in Central Sulawesi is another important protected area. The Nature Conservancy is working with local government agencies and NGOs to institute training, participatory analysis, awareness raising, and sustainable enterprise programs. In the Togean Islands, Conservation International has been working for nearly a decade with a local foundation on ecotourism development and policy creation with the goal of creating an environmentally sustainable model for regional development and community-based conservation. The local government recently declared its intention to proclaim the Togeans as a marine park for tourism, covering 4,000 km2 of marine and terrestrial habitats. The 1,730-km2 Komodo National Park includes not only the islands inhabited by Komodo dragons, but also 1,320-km2 of coral reefs. Conservation programs there have focused on raising awareness, sustainable fishing techniques, capacity building and the establishment of responsible diving and ecotourism businesses.

BirdLife Indonesia is very active throughout the hotspot, and, together with the World Bank-GEF, promoted a process to resolve community-government conflicts that had prevented progress in forest conservation on the Sangihe-Talaud Islands between northern Sulawesi and the Philippines (with the specific aim of protecting two shrinking forest areas that are the sole home of seven endemic bird species). On Sumba Island in the Lesser Sundas, the work of BirdLife Indonesia and BirdLife International helped lead to the establishment of two national parks to protect the most important remaining forests on the island and promoted community action to stop illegal logging and trapping in the area. BirdLife Indonesia has also undertaken surveys and identified priorities for action throughout the Lesser Sundas and the Moluccas. On Tanimbar Island, in the southeast Moluccas, this has been followed up with a project to help local government and communities plan the management of their still-extensive forests (which are home to eight endemic bird species). On Halmahera, development of conservation action to protect the critical forests on the island was suspended with the violence in 1999 and has been revived in 2004.

Further Reading

  • Birdlife International. 2003. Saving Asia's Threatened Birds: A Guide for Government and Civil Society. Cambridge: Birdlife International.
  • Brown, N. 1998. Out of control: Fires and forestry in Indonesia. Trends in Ecology & Evolution 13: 41.
  • Dickerson, R.E. 1928. Distribution of life in the Philippines. Manila: Bureau of Printing. ISBN: B0000EF5YJ.
  • FWI/GFW. 2002. The State of the Forest: Indonesia. Bogor, Indonesia: Forest Watch Indonesia & Washington DC: Global Forest Watch. ISBN: 1569734925.
  • Monk, K.A., de Fretes, Y. & Reksodihardjo-Lilley, G. 1997. Ecology of Nusa Tenggara and Maluku. Vol. V of The Ecology of Indonesia Series. Singapore: Periplus & Oxford: Oxford University Press. ISBN: 9625930760.
  • Rombang, W.M., Trainor, C., & Lesmana, D. 2002. Daerah Penting Bagi Burung (Important Bird Areas): Nusa Tenggara. Bogor: Phka/BirdLife Indonesia.
  • Rombang, W.M., Saryanthi, R. & Lesmana, D. In press. Daerah Penting Bagi Burung (Important Bird Areas): Sulawesi. Bogor: Phka/BirdLife Indonesia.
  • Rombang, W.M., Persulessy, Y. & Purmiasa, D. In press. Daerah Penting Bagi Burung (Important Bird Areas): Maluku. Bogor: Phka/BirdLife Indonesia.
  • Wallace, A.R. 1876. The Geographical Distribution of Animals. London: Macmillan. ISBN: B000SMZN84.
  • Whitten, A., Whitten, J., Mittermeier, C.G., Supriatna, J. & Mittermeier, R.A. 1997. Indonesia. In R.A. Mittermeier, P. Robles Gil & C.G. Mittermeier. Megadiversity: Earth's Biologically Wealthiest Nations. Monterrey, Mexico: CEMEX. ISBN: B000IY24R0.
  • 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.

 

Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Conservation International. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Conservation International should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

Glossary

Citation

International, C. (2010). Biological diversity in Wallacea. Retrieved from http://www.eoearth.org/view/article/150632

0 Comments

To add a comment, please Log In.