Southeastern Asia: Island of Luzon in the Philippines

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The mountainous, often cloudy Luzon Pine Forests [IM0302] are a unique habitat in the Philippines. Regular fires have led to a parkland structure of grass with widely dispersed trees and prevented broadleaf trees from establishing over large areas. However, more typical montane forest covers so much of the ecoregion that some experts would lump the pine forests with the Luzon Montane Rain Forest [IM0122] ecoregion. The ecoregion has been exploited for its trees and mineral resources in the past; shifting agriculture and mining are the greatest current threats.

  • Scientific Code
  • Ecoregion Category
  • Size
    2,700 square miles
  • Status
  • Habitats

Location and General Description
Luzon is located in the western Pacific Ocean. It is the largest island in the Philippines and lies at the northern end of the island group. The Luzon Pine Forests [IM0302] ecoregion is entirely within the Central Cordillera Mountain Range of northwestern Luzon and includes all regions above 1,000 m, except a large tract of montane forest at the northern end (see ecoregion 102). Included in this ecoregion are some of Luzon's highest mountain peaks: Mt. Puguis, Mt. Polis, Mt. Data, and Mt. Pulog.

The geologic history of the Philippines is very complex and has had tremendous influence on the biota currently found there. Luzon has developed many unique species of plants and animals as a result of its long-standing isolation from other landmasses. Parts of the Luzon highlands were established as a result of volcanic activity and the friction of the Australian and Asian plates at least 15 million years ago. The highlands began to take their current form over the next 10 million years. Luzon is therefore oceanic in character, having never been connected to mainland Asia. Even during the Pleistocene, as world sea levels fell 120 m, Luzon expanded to become a larger island including the modern islands of Polillo, Marinduque, and Catanduanes but never connecting to other regions of the Philippines or to mainland Asia (Heaney and Regalado 1998).

The ecoregion receives about 2,500 mm of rain a year (even more than 4,000 mm on Mt. Pulog in some years), but this rain is highly seasonal. Often the pine forests of Luzon are categorized as monsoon forests because of the pronounced dry period (November-April) between rain (May-August, with July and August being the wettest). The temperature of the pine forests averages about 20°C and rarely exceeds 26°C. The forests are affected by typhoons that sweep across the South China Sea, hitting the western side of Luzon every few years. These typhoons are a major element of disturbance.

Most of the ecoregion's area is covered by grassland that is interspersed with trees. The pronounced dry periods and periodic fires favor the Benguet pine or saleng (Pinus insularis, also known as P. kesiya). This species ranges in elevation between 1,000 and 2,500 m and is also present in mainland Asia. However, montane forest interdigitates with the pine forests and covers much of the ecoregion's surface area. This is particularly true in Balbalasang-Balbalan protected area, which is nearly all montane forest. Species lists for the ecoregion therefore include many animals that are limited to montane forests within the ecoregion and are not even found in pine forests.

Biodiversity Features
The ecoregion is inhabited by nine near-endemic mammal species and seven strictly endemic mammals (table 1). All but one of these species belongs to the mouse and rat family, Muridae, which has undergone extensive adaptive radiation on Luzon. Cloud rats (genera Crateromys and Phloeomys) occur only in the northern Philippines and are perhaps the most unique and characteristic of mammals here. These large, bushy-tailed creatures look more like squirrels than typical rats (Heaney and Regalado 1998). All are subject to heavy hunting pressures (Heaney et al. 1998). Three relatively large mammals occur in the ecoregion: long-tailed macaque (Macaca fascicularis), Philippine warty pig (Sus philippensis), and Malay civet Viverra tangalunga). All are fairly widespread, and none are listed as threatened by IUCN (IUCN 2000). However, habitat destruction affects all three species, and hunting affects all but the Malay civet.

Table 1. Endemic and Near-Endemic Mammal Species.

  Family Species
Pteropodidae Otopteropus cartilagonodus
Muridae Abditomys latidens
Muridae Apomys abrae
Muridae Apomys datae
Muridae Apomys sacobianus
Muridae Batomys dentatus*
Muridae Batomys granti
Muridae Bullimus luzonicus
Muridae Carpomys melanurus*
Muridae Carpomys phaeurus*
Muridae Celaenomys silaceus*
Muridae Chrotomys whiteheadi*
Muridae Crateromys schadenbergi*
Muridae Phloeomys pallidus
Muridae Rhynchomys soricoides*
Muridae Tryphomys adustus

An asterisk signifies that the species' range is limited to this ecoregion.

The Luzon Pine Forests [IM0302] are home to twenty-three near-endemic birds, none of which are strictly limited to the ecoregion (table 2). Perhaps the bird species most characteristic of the ecoregion is also one of its most widespread worldwide. Red crossbill (Loxia curvirostra), known primarily from high-latitude coniferous forests, reaches its southernmost extent in the Old World in the mountains of the Central Cordillera (the populations in Central America, notably Nicaragua, are further south). Dickinson et al. (1991) listed eleven other bird species that typify the pine forests, including one tit (Parus elegans), a nuthatch (Sitta frontalis), and thrush (Turdus poliocephalus). These groups of birds are familiar to many people of northern latitudes and are indicative of the unique habitat this ecoregion represents within the Philippines.

Table 2. Endemic and Near-Endemic Bird Species.

  Family Common Name Species
Turnicidae Luzon buttonquail Turnix worcesteri
Rallidae Brown-banded rail Lewina mirificus
Columbidae Luzon bleeding-heart Gallicolumba luzonica
Columbidae Flame-breasted fruit-dove Ptilinopus marchei
Psittacidae Luzon racquet-tail Prioniturus montanus
Cuculidae Scale-feathered malkoha Phaenicophaeus cumingi
Strigidae Luzon scops-owl Otus longicornis
Apodidae Whitehead's swiftlet Aerodramus whiteheadi
Pittidae Whiskered pitta Pitta kochi
Laniidae Grey-capped shrike Lanius validirostris
Turdidae Ashy thrush Zoothera cinerea
Muscicapidae Luzon redstart Rhyacornis bicolor
Timaliidae Golden-crowned babbler Stachyris dennistouni
Timaliidae Chestnut-faced babbler Stachyris whiteheadi
Sylviidae Philippine bush-warbler Cettia seebohmi
Sylviidae Long-tailed bush-warbler Bradypterus caudatus
Muscicapidae Rusty-flanked jungle-flycatcher Rhinomyias insignis
Muscicapidae Ash-breasted flycatcher Muscicapa randi
Pachycephalida Green-backed whistler Pachycephala albiventris
Rhabdornithidae Long-billed rhabdornis Rhabdornis grandis
Dicaeidae Flame-crowned flowerpecker Dicaeum anthonyi
Fringillidae White-cheeked bullfinch Pyrrhula leucogenis
Oriolidae White-lored oriole Oriolus albiloris

An asterisk signifies that the species' range is limited to this ecoregion.

Current Status
The status of the ecoregion is hard to assess from published sources. Pines from the ecoregion have been exploited for a long time. Resin from the pines provided an important commercial source of turpentine during the Spanish colonial period (Heaney and Regalado 1998).

One of the protected areas in the ecoregion, Mt. Pulog, is the highest peak in Luzon (table 3). Mt. Pulog is important globally as a center of plant diversity with many local endemics (Davis et al. 1995) and as a key site for threatened birds, with six (Collar et al. 1999). The mountain, like much of the ecoregion, is valuable for water quality in Luzon. The size of the park (11,500 ha) may be adequate, although there was initial difficulty in demarcating the park boundary when it was established in 1987 (Davis et al. 1995). The park continues to have problems with agricultural encroachment and wildlife exploitation (Collar et al. 1999). Mt. Polis is also listed as a key site for threatened birds, with six species having been recorded. Unfortunately, little forest remains on Mt. Polis, and it receives no legal protection (Collar et al. 1999).

Table 3. WCMC (1997) Protected Areas That Overlap with the Ecoregion.

  Protected Area Area (km2) IUCN Category
Balbalasang-Balbalan 160 VI
Mt. Data 300 V
Bessang Pass 10 III
Mts. Pulog, Nueva Vizcaya, Ifugao, Benguet 80 II
Total 550  

Ecoregion numbers of protected areas that overlap with additional ecoregions are listed in brackets.

Types and Severity of Threats
The population growth of the Philippines and the extreme poverty of many has forced people to cultivate land at increasingly high altitudes. Population growth and rural poverty are definitely threats to the ecoregion. More typical threats to the biodiversity of the ecoregion exist but are perhaps symptoms of these overarching problems.

Fire and habitat conversion are the greatest threats, and they are in some ways the same problem. Fire is a natural process in the ecoregion, but human-induced fire is being used to clear extensive areas for growing vegetables and cut flowers. The increased number of fires limits regeneration of some forest plants; it also makes the region susceptible to invasive grasses (Davis et al. 1995). Logging (both legal and illegal) is a threat everywhere in the Philippines and is another means of habitat destruction.

Mining is an ever-present threat. The Central Cordillera is famous for its mineral wealth, including copper and gold. In fact, most of the mountain range is included within mining application and exploration areas. Wildlife exploitation is also a serious problem in many parts with species being sought for trade and consumption.

Justification of Ecoregion Delineation
MacKinnon (1997) identified seven subunits in the Philippines, and the 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 primarily on Heaney (1993).

In Luzon we delineated three ecoregions, which correspond to MacKinnon's subunit 26a. First, we used the 1,000-m contour from the DEM (USGS 1996) to delineate the montane forests from the lowland forests. The Luzon Montane Rain Forests [IM0122] are made up primarily of the montane moist evergreen forests along the Sierra Madre, northern Central Cordillera, and Zambales mountain ranges. MacKinnon (1997) shows an area of freshwater swamp forests as part of the original vegetation of Luzon Island, which we combined with the remaining lowland forest of Luzon to form the Luzon Rain Forests [IM0123]. These freshwater swamps, in the valley to the east of the Zambales Mountain Range and in the Cagayan River plains, have been converted to rice fields (D. Madulid, pers. comm., 1999). Following Stattersfield et al. (1998) and Dickinson et al. (1991), we placed the Lubang Islands with the Luzon Rain Forests [IM0123]. The conifer forests in the Central Cordillera dominated by Banguet pine (Pinus insularis, also known as P. kesiya) were designated as the Luzon Tropical Pine Forests [IM0302].

References for this ecoregion are currently consolidated in one document for the entire Indo-Pacific realm.
Indo-Pacific Reference List

Prepared by: John Lamoreux
Reviewed by: