The Sulawesi montane rain forests harbor some of the most unique animals on Earth. The islands are located in the region known as Wallacea, which contains a distinctive fauna representing a mix of Asian and Australasian species. Sulawesi, Indonesia (Photograph by David Olson)
A fruit-eating pig with large curly tusks, a dwarf buffalo, four monkey species, and cuscuses exemplify a truly unique mammal community.
Like the hub of a wheel, Sulawesi is surrounded by a variety of exotic ocean basins, including the Flores Sea, the Banda Sea, the Moluccas Sea, the Java Sea, and the Straits of Makassar, as well as the diverse islands of Borneo, Java, Flores, Halmahera, and the Philippines. Although more than half of the original forest has been cleared, Sulawesi still supports tracts of montane moist forests in areas of steep slopes that are unsuitable for agriculture.
Location and General Description
This ecoregion represents these montane forests above 1,000 meters (m), whereas the lowlands constitute a separate ecoregion. Most of Sulawesi lies above 500 m, and about 20 percent of the total land area-mostly the central region-is above 1,000 m. Based on the Köppen climate zone system, this ecoregion falls in the tropical wet climate zone. As might be surmised from its shape, Sulawesi has a complex geologic history and is composed of three geologic provinces based on that history. West and East Sulawesi form two of the geologic provinces, separated by the Palu-Koro fault, which runs from the town of Palu to the Gulf of Bone. The third geologic province consists of the Tokala region on the northeast peninsula, the Banggai Islands, Butung Island, and the Sula Islands. East and West Sulawesi collided approximately 13-19 million years ago, and ultrabasic rocks were exposed as East Sulawesi overrode the western portion. The forces that caused the collision are still at work, and Sulawesi is being torn apart today. The surface geology of Sulawesi is a diverse patchwork of ophiolites, Mesozoic sedimentary rocks, Tertiary sedimentary and igneous rocks, and Quaternary volcanics and sediments. Active volcanoes are located on the northern arm of Sulawesi.
Above 1,000 m, forest trees become shorter and less massive, and epiphytes such as orchids become more common. Whereas the forests of Sulawesi's lowlands are not dominated by any particular tree family, the forests in the lower montane region are dominated by oaks (four species of Lithocarpus) and chestnut (two species of Castanopsis). An example association includes Phyllocladus, Agathis dammara, and Eugenia dominated by Castanopsis. Upper montane forest contains conifers (pines and related Gymnosperms such as Podocarpus spp., Dacrycarpus spp., Dacrydium spp., Phyllocladus spp.) and the magnificent and commercially important Agathis spp. The highest peaks have sub-alpine forests with yet smaller trees whose branches bear epiphytic lichens and a ground cover of shrubs, colorful herbs, and grasses.
|Table 1. Endemic and Near-Endemic Mammal Species.|
|An asterisk signifies that the species' range is limited to this ecoregion.|
Wallace's Line, running from between Bali and Lombok and between Sulawesia and Borneo, marks the location of a deep oceanic trench and the point over which land animals and plants could not cross easily. Similarly, Lydekker's Line, running from between Timor and the Australian shelf to between Halmahera, Seram, and New Guinea, marks the point where Australasian flora and fauna could not easily pass. Sulawesi lies between these two lines. Sulawesi's location, geologic history, and long geographic isolation have created Sulawesi's distinctive fauna. There is variability, different among various animal and plant groups, in the amount of interchange between other biogeographic areas in the region, which led to the evolution of a large number of species endemic to the island. Although not species-rich relative to Borneo or Java, Sulawesi is high in endemicity because of its long isolation from Asia and Australia in Wallacea. This ecoregion exhibits high plant endemism, and the several distinct forest types provide habitat for the highest number of endemic mammals in Asia and several endemic birds.
The ecoregion harbors 102 mammal species, of which 33 species are endemic or near endemic (Table 1). Together with the lowland forests, the montane forests of Sulawesi have the highest recorded number of endemic mammals among the Indo-Pacific ecoregions. These endemic species include the endangered mountain anoa (Bubalus quarlesi) and crested macaque (Macaca nigra) and the vulnerable babirusa (Babyrousa babyrussa) and Sulawesi montane long-nosed squirrel (Hyosciurus heinrichi).
There are approximately 168 bird species listed as resident in the ecoregion, of which 44 species are endemic or near endemic (Table 2). The ecoregion also overlaps the montane portions of the Sulawesi Endemic Bird Area (EBA). Of the fifty-four restricted-range bird species found in the EBA, fourteen species are found in both lowland and montane Sulawesi, and twenty-two species are only found in the uplands of Sulawesi. Nineteen of these montane species are found nowhere else on Earth. Two montane bird species are classified as threatened: the endangered Lompobattang flycatcher (Ficedula bonthaina) and the vulnerable Matinan flycatcher (Cyornis sanfordi).
|Table 2. Endemic and Near-Endemic Bird Species.|
|Accipitridae||Small sparrowhawk||Accipiter nanus|
|Rallidae||Platen's rail||Aramidopsis plateni|
|Rallidae||Bare-faced rail||Gymnocrex rosenbergii|
|Rallidae||Isabelline waterhen||Amaurornis isabellinus|
|Scolopacidae||Sulawesi woodcock||Scolopax celebensis*|
|Columbidae||Sulawesi ground-dove||Gallicolumba tristigmata|
|Columbidae||Red-eared fruit-dove||Ptilinopus fischeri*|
|Columbidae||White-bellied imperial-pigeon||Ducula forsteni|
|Columbidae||Grey-headed imperial-pigeon||Ducula radiata|
|Columbidae||Sombre pigeon||Cryptophaps poecilorrhoa*|
|Loriidae||Yellow-and-green lorikeet||Trichoglossus flavoviridis|
|Cuculidae||Sulawesi hawk-cuckoo||Cuculus crassirostris|
|Strigidae||Ochre-bellied hawk-owl||Ninox ochracea|
|Tytonidae||Minahassa owl||Tyto inexspectata|
|Caprimulgidae||Diabolical nightjar||Eurostopodus diabolicus|
|Alcedinidae||Scaly kingfisher||Actenoides princeps|
|Meropidae||Purple-bearded bee-eater||Meropogon forsteni|
|Coraciidae||Purple-winged roller||Coracias temminckii|
|Meliphagidae||Dark-eared honeyeater||Myza celebensis*|
|Meliphagidae||Greater streaked honeyeater||Myza sarasinorum*|
|Pachycephalida||Olive-flanked whistler||Hylocitrea bonensis*|
|Pachycephalida||Maroon-backed whistler||Coracornis raveni*|
|Pachycephalida||Sulphur-bellied whistler||Pachycephala sulfuriventer|
|Rhipiduridae||Rusty-flanked fantail||Rhipidura teysmanni|
|Dicruridae||Sulawesi drongo||Dicrurus montanus|
|Campephagidae||Cerulean cuckoo-shrike||Coracina temminckii|
|Campephagidae||Pygmy cuckoo-shrike||Coracina abbotti*|
|Turdidae||Sulawesi thrush||Cataponera turdoides*|
|Turdidae||Great shortwing||Heinrichia calligyna*|
|Sturnidae||Pale-bellied myna||Acridotheres cinereus|
|Sturnidae||Sulawesi myna||Basilornis celebensis|
|Sturnidae||Fiery-browed myna||Enodes erythrophris|
|Muscicapidae||Lompobattang flycatcher||Ficedula bonthaina*|
|Muscicapidae||Matinan flycatcher||Cyornis sanfordi*|
|Muscicapidae||Blue-fronted flycatcher||Cyornis hoevelli*|
|Zosteropidae||Black-ringed white-eye||Zosterops anomalus|
|Zosteropidae||Streak-headed white-eye||Lophozosterops squamiceps*|
|Sylviidae||Chestnut-backed bush-warbler||Bradypterus castaneus|
|Sylviidae||Sulawesi leaf-warbler||Phylloscopus sarasinorum|
|Dicaeidae||Crimson-crowned flowerpecker||Dicaeum nehrkorni|
|Fringillidae||Mountain serin||Serinus estherae|
|An asterisk signifies that the species' range is limited to this ecoregion.|
Two Centres of Plant Diversity are found in the uplands of Sulwesi: Dumoga-Bone National Park and Pegunungan Latimojong. The montane forests of Dumoga-Bone National Park contain a rich gene pool of timber trees and rattans and are dominated by Eugenia, Shorea, and Agathis, with an abundance of rattans in the understory. The lower montane forests of Pegunungan Latimojong and contain Lithocarpus, Phyllocladus hypophyllus, Podocarpus steupi, and Taxus sumatrana, whereas the upper montane areas contain Vaccinium and Rhododendron vanvuurenii, Hypericum leschenaultii, and Drimys piperata. The area extends to 3,455 m and contains extensive sub-alpine vegetation above 3,200 m.
This ecoregion is still largely intact, with about three-quarters of the original habitat remaining. Most of the habitat destruction has occurred in the southwestern portion, and large blocks of forest remain in the northern and eastern montane areas of the island. The twenty-nine protected areas cover 23 percent of the ecoregion (Table 3). The average size of a protected area in this ecoregion is 602 square-kilometers (km2), and there are five protected areas that exceed 1,000 km2.
Types and Severity of Threats
The steep slopes and the relative lack of commercially valuable tree species help to discourage logging activity. However, the logging that has occurred has had devastating effects on the landscape and the ecosystems; for instance, extensive erosion on surrounding deforested slopes has clogged the irrigation systems of the once fertile rice fields of Palu Valley. Hunting and anthropogenic fires are also serious threats to the wildlife assemblages and habitat. Hunters set fires to facilitate hunting of anoa, creating montane meadows. Upper montane and sub-alpine forests are subject to periods of drought, during which the oil-rich leaves of Rhododendron, Vaccinium, and Gaultheria easily catch fire. With repeated burning, alang-alang grass (Imperata cylindrica) may become dominant. Other threats include transmigration and local clearance.
|Table 3. WCMC Protected Areas That Overlap with the Ecoregion.|
|Protected Area||Area (km2)||IUCN Category|
|Kelompok Hutan Buol Toli-toli||3,920||PRO|
|Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.|
Justification of Ecoregion Delineation
There have been several attempts to divide the bioregion into biogeographic units. Because many of the islands have distinct natural faunal communities and a high degree of endemism, the more recent attempts have used faunal dissimilarities-especially birds-to identify distinct biogeographic units. Because detailed floral data are largely unavailable across most of the bioregion, we followed these authors in delineating ecoregions based on distribution of biomes and vertebrate communities.
On Sulawesi island we delineated two ecoregions: the Sulawesi lowland rain forests and Sulawesi montane rain forests. These represent the tropical lowland and montane tropical moist forests, respectively. The small patches of monsoon forests on the southwest peninsula of Sulawesi and on Butung Island were included in the Sulawesi lowland rain forests but should be considered a distinct habitat type in an ecoregion-based conservation assessment to ensure representation.
Additional information on this Ecoregion
- For a shorter summary of this entry, see the WWF WildWorld profile of this ecoregion.
- To see the species that live in this ecoregion, including images and threat levels, see the WWF Wildfinder description of this ecoregion.
- World Wildlife Fund Homepage
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