Greater Negros-Panay rain forests

Content Cover Image

Bandila-an, Siquijor Island, Philippines Photograph by Tom Brooks

Introduction

caption Catingas, Philippines. (Source: Photograph by © Cynthia Gneiser/Zegrahm Expeditions)

The Greater Negros-Panay Rain Forests ecoregion, including the Western Visayas and parts of additional political regions, appears as a number of isolated islands, but during the last ice ages these islands were (for the most part) part of one continuous island. The islands contain a unique mix of Sundaic and Philippine mammals and birds, including leopard cats and endemic pigs and deer species. Sibuyan, a small mountainous island surrounded by deep water, contains five endemic mammals and several restricted-range birds and nearly qualifies as an ecoregion in itself.

Location and General Description

The ecoregion includes the large island of Negros, Panay, and Cebu and the smaller islands of Masbate, Ticao, and Guimaras; Sibuyan, Romblon, Tablas, and Siquijor are moderately isolated and distinctive. The climate of the ecoregion is tropical wet. The Visayas receive approximately 2,419 millimeters (mm) of rainfall annually. July and August are the wettest months. The west coasts of Panay and Negros experience a dry season between November and February.

caption WWF

Most of these islands have been uplifted above water in the last 6 million years or less. Sibuyan Island contains pre-Tertiary schists, marble, volcanics, and ultramafics. Cebu contains a rugged mountain spine, and 73 percent of the island contains slopes greater than 18 percent. The geology of Cebu includes limestones, marls, and karst topography. Negros contains a string of volcanic mountains. The channel between Greater Negros-Panay and the surrounding islands of Luzon and Greater Mindanao is more than 120 meters (m) deep. During the last ice age (late Pleistocene), sea level was approximately 120 m below current levels and Greater Negros-Panay was separated from ice age Luzon and the Eastern Visayas by a narrow channel. Except for the eastern portion of Panay and much of Masbate, the islands generally are fairly rugged, with the highest elevation being 2,465 m Mt. Canlaon in north-central Negros.

Vegetation types in the ecoregion are diverse and include beach vegetation, mangroves, tropical lowland rain forest, montane forests, and grasslands and heath forests. Beach forest merges with other forest types away from the coast and includes Casuarina and Barringtonia mixed with other lowland species. Palms, vines, bamboo, and Pterocarpus indicus are present only in rare back-beach swamps. This habitat type is extremely rare because of coastal habitation.

The lowland evergreen dipterocarp rain forest was once the dominant vegetation of the ecoregion and contained Dipterocarpus spp., Shorea spp., Hopea spp., Pterocarpus indicus, and pandans. Philippine dipterocarp forest is quite tall (45-65 m) and dense, with three layers of canopy. Lianas and bamboo are rare in mature forest but common in poorly developed evergreen forest. Ferns, orchids, and other epiphytic plants are found on the larger trees. At higher elevations there are only two canopy layers, tree stature is lower, and there are more epiphytes. Upper hill dipterocarp forest is found at elevations of 650-1,000 m and contains dominant Shorea polysperma and oaks, chestnuts, and elaeocarps. At approximately 1,000 m the montane forest contains oaks and laurels. The mossy upper montane forest generally is found at elevations over 1,200 m, where humidity is constantly high. This stunted, single-story moss- and epiphyte-covered forest contains tree ferns up to 10 m high.

Biodiversity Features

 
Table 1. Endemic and Near-Endemic Mammal Species.
Family Species
Sorcidae Crocidura mindorus
Sorcidae Crocidura negrina*
Muridae Apomys sp. A*
Muridae Apomys sp. B* (Sibuyan only)
Muridae Apomys sp. C* (Sibuyan only)
Muridae Chrotomys sp. A* (Sibuyan only)
Muridae Crateromys heaneyi*
Muridae Tarsomys sp. A* (Sibuyan only)
Pteropodidae Nyctimene rabori*
Pteropodidae Dobsonia chapmani*
Pteropodidae Haplonycteris sp. A* (Sibuyan only)
Suidae Sus cebifrons*
Cervidae Cervus alfredi*
An asterisk signifies that the species' range is limited to this ecoregion

Greater Negros-Panay contains a unique mix of Sundaic and Philippine mammals and birds, including leopard cats and endemic pig and deer species. Fifty-eight mammals inhabit the ecoregion, and thirteen mammal species are endemic or near endemic (Table 1). Six of these species (Crocidura mindorus, two Apomys spp., and Chrotomys, Tarsomys, and Haplonyteris spp.) are limited to Sibuyan Island within the ecoregion (Crocidura mindorus is also found on Mindoro); most of these species have yet to be named. Two endemic large vertebrates are especially notable: the Philippine spotted deer (Cervus alfredi) and the Visayan warty pig (Sus cebifrons). The Visayan warty pig is critically endangered, and the Philippine spotted deer is endangered. One found only on Negros and Cebu, the Philippine bare-backed fruit bat (Dobsonia chapmani), is now believed to be extinct because of guano mining, deforestation, and hunting.

Sibuyan, a small mountainous (to 2,052 m) island surrounded by deep water within the ecoregion, is outstanding in itself. Sibuyan contains six endemic mammals (five strict endemics) and is considered a Secondary Area by BirdLife International because of the existence of three restricted-range birds. These restricted-range birds are also found elsewhere but have no clear affinities. One hundred thirty-one bird species have been recorded on the island, a high number for an isolated island of only 463 km2. Sibuyan still contains about half of its original forest cover (100-150 km2), including some extremely rare (in the Philippines) lowland forest; unfortunately, logging threatens the remainder. Sibuyan Island is also a Centre of Plant Diversity (CPD), containing beach vegetation, mangroves, lowland rain forest, montane forests, and grasslands and heath forests. There are an estimated 700 vascular plant species on the island, including 54 endemic species. The flora is closely related to that of Luzon. Sibuyan contains valuable timber trees, almaciga (Agathis philippensis) resins, and ornamental plants and has good potential for tourism.

caption Bandila-an, Siquijor Island, Philippines. (Source: Photograph by Tom Brooks)

The Asian leopard cat (Prionailurus bengalensis), an Asian species, is found on Negros, Panay, and Cebu within the ecoregion. Also found on Palawan, the Negros leopard cat is a subspecies. Threatened endemic or near-endemic mammals include the critically endangered Negros shrew (Crocidura negrina) and Philippine tube-nosed fruit bat (Nyctimene rabori), the endangered Mindoro shrew (Crocidura mindorus) and Panay bushy-tailed cloud rat (Crateromys heaneyi), and the widespread but endangered golden-crowned fruit bat (Acerodon jubatus).

The Visayan warty pig has been extirpated from Masbate, Guimaras, Cebu, and Siquijor and now lives only in isolated areas of Negros and Panay, where hunting of them is still intense. There are no effective protected areas in the fragmented range of S. cebifrons. The Visayan warty pig is smaller than its closer relative, the Philippine warty pig (Sus philippensis), which the IUCN considers rare and declining. The Visayan warty pig once inhabited both lowland and montane rain forests and may have thrived in disturbed areas as well.

The Philippine spotted deer (Cervus alfredi) has been extirpated from Guimaras, Cebu, and Siquijor and is now limited to the Mt. Madja-Mt. Baloy area of west Panay and some scattered forest fragments on Negros. A very small population apparently was located on Masbate in 1991. Small populations are protected in Mt. Canlaon National Park, North Negros Forest Reserve, and the Mount Talinis/Lake Balinsasayao Reserve. The Philippine spotted deer prefers dipterocarp rain forests but also frequents open grassland patches and secondary forest. The population has been reduced by habitat loss and hunting, which are still the main threats.

 
Table 2. Endemic and Near-Endemic Bird Species.
Family Common Name Species
Turnicidae Spotted buttonquail Turnix ocellata
Columbidae Negros bleeding-heart Gallicolumba keayi*
Columbidae Negros fruit-dove Ptilinopus arcanus*
Strigidae Mantanani scops-owl Otus mantananensis
Apodidae Philippine needletail Mearnsia picina
Bucconidae Tarictic hornbill Penelopides panini*
Bucconidae Writhed-billed hornbill Aceros waldeni*
Monarchidae Celestial monarch Hypothymis coelestis
Campephagidae Blackish cuckoo-shrike Coracina coerulescens
Campephagidae White-winged cuckoo-shrike Coracina ostenta*
Irenidae Philippine leafbird Chloropsis flavipennis
Muscicapidae Negros jungle-flycatcher Rhinomyias albigularis*
Muscicapidae Ash-breasted flycatcher Muscicapa randi
Muscicapidae Black shama Copsychus cebuensis*
Pycnonotidae Streak-breasted bulbul Ixos siquijorensis*
Timaliidae Flame-templed babbler Stachyris speciosa*
Timaliidae Panay striped-babbler Stachyris latistriata*
Timaliidae Negros striped-babbler Stachyris nigrorum*
Estrildidae Green-faced parrotfinch Erythrura viridifacies
Dicaeidae Cebu flowerpecker Dicaeum quadricolor*
Dicaeidae Visayan flowerpecker Dicaeum haematostictum*
Dicaeidae Scarlet-collared flowerpecker Dicaeum retrocinctum
Lanidae Grey-capped shrike Lanius validirostris
An asterisk signifies that the species' range is limited to this ecoregion.

The Greater Negros-Panay ecoregion encompasses two Endemic Bird Areas (EBAs) (Negros and Panay; Cebu) and two Secondary Areas (Tablas, Romblon, and Sibuyan; Siquijor). There are seventeen restricted-range bird species in the Negros and Panay EBA, six restricted-range species in Cebu (five additional species), and several others in the adjacent Secondary Areas. A total of twenty-three endemic or near-endemic species are found in the ecoregion. An extremely high proportion of these birds are threatened. These include the critically endangered Negros bleeding-heart (Gallicolumba keayi), Negros fruit-dove (Ptilonopus arcanus), Tarictic hornbill (Penelopides panini), writhed-billed hornbill (Aceros waldeni), white-throated jungle flycatcher (Rhinomyias albigularis), scarlet-collared flowerpecker (Dicaeum retrocinctum), Cebu flowerpecker (Dicaeum quadricolor), and twelve endangered restricted-range bird species. Almost no forest remains on Cebu, and the species with these habitats on Cebu are in a critical situation.

The critically endangered Philippine crocodile (Crocodylus mindorensis) was historically found on the islands of Luzon, Mindoro, Masbate, Samar, Jolo, Negros, Busuanga, and Mindanao, but the only remaining populations are found on Mindoro, Negros, Mindanao, and Busuanga. Whereas the decline of the species initially was driven by overexploitation, habitat loss and human persecution are now the principal threats to the Philippine crocodile. Surveys in 1980-1982 revealed a total wild population of approximately 500-1,000 individuals, but current wild populations may be approximately 100 nonhatchlings. Captive breeding efforts are being led by the Crocodile Farming Institute, an entity of the Philippine government.

Current Status

"Nowhere in the Philippines is environmental degradation quite so acute, and the need for immediate conservation action quite so pressing, as in the West Visayas, or Negros Faunal Region". This ecoregion harbors the some of the highest levels of endemism but has suffered a disproportionate share of deforestation, and to compound the problem the area is underrepresented in the national protected area system.

The Philippines were once almost completely forested, but forests have been significantly reduced in this ecoregion and the rest of the Philippines. Aerial surveys indicate that Sibuyan Island still contains substantial areas of closed-canopy forest. Forests on Masbate Island have been devastated by improper farming and pasture practices. Remaining closed-canopy forests on Panay straddle the main mountain range. Open-canopy dipterocarp forests can still be found on Panay in steep areas at elevations between 690 and 2,150 m. Closed-canopy forests can also be found on Negros. Mt. Canlaon contains broadleaf and mossy forest on steep slopes at elevations of 490 to 1,870 m; there was little to no buffer zone between this forest and cultivation in 1992. On Mt. Mandalagan, remaining mossy forest is surrounded by a large buffer of residual open-canopy forest. A patch of closed-canopy forest also remains above Dumaguete City in Negros. In 1988, Negros was only 4 percent forested and Panay was 8 percent forested.

Cebu contains approximately 15 km2, or 0.3 percent, of its original dipterocarp forest cover; this has led to the near extinction of the island's endemic species. Little of the ecoregion is protected (Table 3).

Types and Severity of Threats

 
Table 3. WCMC (1997) Protected Areas That Overlap with the Ecoregion.
Protected Area Area (km2) IUCN Category
Sampunong-Bolo Bird Sanctuary 3 I
Bulabog-Putian 30 III
Central Cebu 200 VI
Mt. Canlaon 320 II
Sudlon 30 VI
Olango Island Complex 50 I
Guadalupe Mabugnao-Mainit Hot Spring 20 PRO
Total 653  
Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.

Habitat destruction is the main threat to biodiversity in the Philippines, and Greater Negros-Panay is no different. 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. Mangroves are used locally for firewood, dyes, and tannins.

Hunting and the wild pet trade are also significant threats in Greater Negros-Panay. Leopard cats have been hunted for their pelts, and kittens are sold as pets.

Justification of Ecoregion Delineation

MacKinnon identified seven subunits in the Philippines, and the Philippine Biodiversity Action Plan demarcated fifteen biogeographic units. Udvardy identified the Philippines as a single biogeographic province. We delineated nine ecoregions in the Philippine islands, including Palawan. We deviated from Udvardy, MacKinnon, Stattersfield et al., and the Philippine BAP in varying degrees and based our delineation of the Philippine ecoregions on Heaney, except that Heaney placed Sibuya, Tablas, and Romblon in a separate region.

We placed the islands of Negros, Panay, Tablas, Sibuyan, Masbate, Ticao, Siquijor, and Cebu into the Greater Negros-Panay Rain Forests ecoregion. MacKinnon also grouped these islands into a single subunit (26b). However, he also included the island of Bohol in this subunit. We followed Heaney and included Bohol as part of the Mindanao-Eastern Visayas rain forests because during the Pleistocene ice ages it was connected to Leyte Island.

Additional information on this ecoregion

 

 

Disclaimer: This article is taken wholly from, or contains information that was originally published by, the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the World Wildlife Fund 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

Fund, W. (2014). Greater Negros-Panay rain forests. Retrieved from http://www.eoearth.org/view/article/153120

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