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The climate of the ecoregion is tropical wet (National Geographic Society 1999), with temperature and rainfall modified by the elevation, which reaches up to 2,700 m. There are extensive, disjunct areas of the island above 1,000 m. Mindanao generally is south of the typhoon track of the storms that usually hit the northern Philippines from July to November (Dickinson et al. 1991). Mindanao and the Visayas have been transported across the western Pacific to their present location during the last 25 million years. Most of these islands have been uplifted above water only in the last 15 million years (Hall and Holloway 1998). During much of the Pleistocene, Mindanao and the Eastern Visayas (Samar, Leyte, and Bohol) were all one island-Greater Mindanao (Heaney 1986)-but the higher elevations of this larger island generally were limited to what is now Mindanao. Vegetation types in the montane forests of Mindanao consist of hill dipterocarp forests, lower and upper montane forest, elfin woodland (mossy forest), and summit grasslands (Davis et al. 1995). The dominant forest type in Mindanao and the rest of the Philippines was dipterocarp forest. Whereas upper hill dipterocarp forest is found at elevations of 650-1,000, individual dipterocarps occur to 1,500 m, and on Mt. Apo, primary dipterocarp forest occurs from 1,000 to 1,600 m. Upper hill dipterocarp forest on Mt. Apo is dominated by the dipterocarps Hopea plagata, Shorea guiso, and Dipterocarpus grandiflorus and species of Cinnamomum, Lithocarpus, Homalanthus, and Musa. There are many epiphytes, mostly ferns and orchids. Tree ferns (Cyathea) and palms (Areca) are also found in the understory (Davis et al. 1995; Heaney and Regalado 1998). The transition zone between dipterocarp forest and montane forest includes increasing numbers of tree ferns, pandans, rattans, and Angiopteris; the dipterocarps Shorea almon, S. polysperma, and Lithocarpus spp.; and Agathis philippensis (Davis et al. 1995). On Mt. Apo, montane forest occurs above approximately 2,000 m. Dominant genera include Lithocarpus, Cinnamomum, Melastoma, Caryota, Calamus, Ficus, Agathis, and numerous Lauraceae (Davis et al. 1995). The mossy upper montane forest generally is found at elevations from 1,200 m to 1,500 m (Davis et al. 1995; Lewis 1988), where humidity is constantly high. This stunted, single-story, moss- and epiphyte-covered forest contains tree ferns up to 10 m high (Dickinson, Kennedy, and Parkes 1991). All surfaces are covered or draped with lichens, bryophytes, begonias, orchids, aroids, Selaginella, and Nephrolepis ferns (Davis et al. 1995).
Mindanao and its neighbor, Basilan, situated adjacent to the Sulu Archipelago, have been influenced by animal dispersal from Borneo, although in recent millennia movement has been primarily in the other direction (Dickinson et al. 1991). Over the course of the most recent ice ages, the Mindanao faunal region has developed its own unique fauna, with a number of endemic vertebrates. There is also variation within the island of Mindanao. Thirty-one bird species are polytypic on the island. Sixteen of these variations are based on differences between isolated mountain ranges, and seven species have races associated with the Zamboanga Peninsula and Basilan Island. There are three species that vary between the uplands and lowlands (Dickinson et al. 1991). Approximately 80 percent of Greater Mindanao's nonvolant mammal species are found nowhere else in the world. Although flying lemurs, tree shrews, tree squirrels, and tarsiers are found on the islands of Greater Mindanao, they are not found on the other large Philippine island of Luzon, just 25 km away from the northern tip of Samar (Heaney and Regalado 1998). More than 30 percent of nonvolant mammals in the ecoregion are endemic to Mindanao only, but the other islands share their species with Mindanao. However, tiny Camiguin and Dinagat islands, located north of Mindanao, contain two and three, respectively, of their own endemic mammals (Heaney 1986; Heaney et al. 1995). Fourteen mammal species are endemic or near endemic to the ecoregion (table 1) Table 1. Endemic and Near-Endemic Mammal Species.
An endemic subspecies of Philippine deer (Cervus mariannus nigricans) is limited to Mindanao. Philippine deer are widespread (though distributed patchily) in the Philippines, being found on Luzon, Mindoro, Samar, Leyte, Mindanao, and the Basilan Islands. The subspecies (and species) is threatened by habitat loss and hunting (Wemmer 1998). The Philippine tree shrew (Urogale everetti), which is found on Mindanao, Dinagat, and Siargao islands, represents an endemic, monotypic genus. There are sixteen species of tree shrews, a diurnal animal that resembles a squirrel but whose dentition, circulatory system, and large braincase are more like those of primates (Nowak 1999a). This species is considered vulnerable (IUCN 2000). The ecoregion also supports a population of the Philippine warty pig (Sus philippensis), which the IUCN considers rare and declining. The Philippine warty pig is widely distributed in the still-forested areas of Luzon, Mindoro, Samar, Leyte, Mindanao, and some of the smaller satellite islands. Many of these forested areas are found in existing national parks. The Philippine warty pig is closely related to Sus barbatus of the Greater Sundas and was once thought to be a subspecies, analogous to the Palawan bearded pig (Sus barbatus ahoenobarbus). The Philippine warty pig is still threatened by hunting and habitat loss (Oliver 1993). Greater Mindanao also supports an endemic genus of Erinaceidae, Podogymura. There are two moonrat species in this genus, both of which are found in Greater Mindanao and one of which is found in the montane regions of Mindanao. The exclusively montane species P. truei, or Mindanao moonrat, is common in montane and mossy forest at elevations from 1,400 m to 2,800 m. Contrary to the IUCN listing, it is not threatened (Heaney et al. 1998; Heaney, pers. comm., 2000). Montane Mindanao is also home to the endangered Greater Mindanao shrew (Crocidura grandis) and the widespread (within the Philippines) but endangered golden-crowned fruit bat (Acerodon jubatus) (Heaney et al. 1998). This ecoregion overlaps with the Mindanao and the Eastern Visayas EBA, but only the montane portions of it. The EBA contains fifty-one restricted-range birds, twenty-six (or possibly twenty-seven) of which are montane and mossy forest specialists and are thus resident in this ecoregion. All of the restricted-range birds are forest species. There are thirty-four endemic or near-endemic bird species in the ecoregion (Kennedy et al. 2000; table 2). Only one of these species is considered threatened: the vulnerable blue-capped kingfisher (Actenoides hombroni). This situation should be contrasted with the adjacent lowland Mindanao and Eastern Visayas rain forests. Although it supports fewer restricted range species, the lowland ecoregion contains nine threatened species (Stattersfield et al. 1998; Collar et al. 1999). Table 2. Endemic and Near-Endemic Bird Species.
In addition to the restricted-range species, the critically endangered Philippine eagle (Pithecophaga jeffreyi) and vulnerable spotted imperial-pigeon (Ducula carola) are found in the ecoregion (Stattersfield et al. 1998; Collar et al. 1999). Mt. Apo on Mindanao is considered a Centre of Plant Diversity (Davis et al. 1995). This spectacular mountain in the southern portion of the Central Cordillera contains primary lowland forest and lower montane forests as well as montane forests found in the Mindanao Montane Rain Forests [IM0128] ecoregion. Much of the lowland forest below 1,000 m has been cleared, but dipterocarp forest is found from 1,000 to 1,600 m.  Current Status
Although the remaining forest is found in isolated patches, most forest remaining on the island of Mindanao is contained in this upland ecoregion. This is in contrast to the largely deforested lowlands of Mindanao and the Eastern Visayas. The conservation status of restricted-range birds is illustrative in this respect: although the upland ecoregion contains more restricted-range species than the lowlands, only one of the upland species is considered threatened, compared with nine threatened species in the lowlands (Stattersfield et al. 1998; Collar et al. 1999). By 1988, approximately 29 percent of Mindanao's forest, including both primary and secondary forests, remained (Stattersfield et al. 1998). There is less today (Development Alternatives 1992). The Zamboanga Peninsula on southwest Mindanao contains a number of isolated fragments, the largest of which is found in the watershed of Zamboanga City. The remaining patches are scattered in hill and montane areas around the peninsula. These patches contained evidence of recent logging in 1992. In southern Mindanao, some large areas of forest remain in hill and montane areas. Political instability, lack of access, and poor commercial values have helped protect some of these areas. Ironically, some of the areas, which had been under now-suspended timber license agreements, are threatened by encroaching agriculture and fire. There are other large blocks of forest in the rest of Mindanao, but they are similarly limited to hill and montane areas (Development Alternatives 1992). Varying levels of protection have been accorded to the protected areas in the ecoregion; by 1988, approximately 50 percent of Mt. Apo National Park had been deforested. In addition to the classic sequence of logging, invasion by kaingineros, and associated hunting and burning, the park is administered by more than one Bureau of Forest Development office and is sometimes occupied by rebel groups (Lewis 1988). Table 3 details the existing protected areas in the ecoregion. Table 3. WCMC (1997) Protected Areas That Overlap with the Ecoregion.
Habitat destruction is the main threat to biodiversity in the Philippines. Logging and shifting cultivation (kaingin) are cited as the primary forces of habitat conversion. Logging takes many forms, from industrial scale to smaller-scale operations that use water buffalo to haul logs out of the forest (Davis et al. 1995). Both the Philippine warty pig and Philippine deer suffer from intense hunting pressure and fragmentation of their remaining habitats. The pigs are in an especially poor situation because they tend to raid crops and are regarded as pests; consequently, there are no effective protections in place for them (Oliver 1993).
MacKinnon (1997) identified seven subunits in the Philippines, and the Philippine Biodiversity Action Plan (Philippine BAP 1997) demarcated fifteen biogeographic units. Udvardy (1975) identified the Philippines as a single biogeographic province. We delineated nine ecoregions in the Philippine islands, including Palawan. We deviated from Udvardy (1975), MacKinnon (1997), Stattersfield et al. (1998), and the Philippine BAP (1997) to varying degrees and based our delineation of the Philippine ecoregions on Heaney (1993). The islands of Leyte, Samar, Dinagat, and Bohol were combined with the lowland rain forests of Mindanao Island to form the Mindanao-Eastern Visayas Rain Forests [IM0129]. We also included the Basilan Islands off the southwest peninsula of Mindanao in this ecoregion, based on Heaney (1993). In Mindanao we used the 1,000-m contour from the DEM (USGS 1996) to delineate the montane forests from the lowland forests. The montane forests of Mindanao were placed into their own ecoregion, the Mindanao Montane Rain Forests [IM0128]. In our delineation of the Mindanao-Eastern Visayas Rain Forests [IM0129] and Mindanao Montane Rain Forests [IM0128] ecoregions, we deviated from MacKinnon (1997). MacKinnon placed both of Mindanao's lowland and montane forests in a single subunit (26c). The Basilan Islands were part of subunit 26d, and the islands of Leyte and Samar made up subunit 26e.
References for this ecoregion are currently consolidated in one document for the entire Indo-Pacific realm. Reviewed by: This text was originally published in the book Terrestrial ecoregions of the Indo-Pacific: a conservation assessment from Island Press. This assessment offers an in-depth analysis of the biodiversity and conservation status of the Indo-Pacific's ecoregions. For more general information on this ecoregion, go to the WildWorld version of this description. All text by World Wildlife Fund © 2001 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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