Filipino Rainforest

The Philippine archipelago comprises 7,107 islands in the western Pacific Ocean. The largest tracts of rainforest occur on the islands of Luzon, Palawan, and Mindanao. The climate in the Philippines varies between the islands. There are four typical weather patterns: constant, even rains throughout the year, no dry season but a definite rainy season, both a rainy and dry season, and no pronounced seasons but decreased rainfall in certain months. Typhoons are one of the major sources of rains throughout the islands and directly affect each island’s weather. Annual rainfall varies throughout the Philippines, but within the rainforests ranges from 2,500 mm to nearly 10,000 mm. The least rainfall occurs on some smaller islands in the off Mindanao while the greatest rainfall occurs in the Luzon montane forests.

Most of the remaining rainforests are lowland evergreen dipterocarp forests with montane at higher elevations. Dipterocarp are trees within the genus Dipterocarpaceae, which are characterized by tall trees with two-winged fruit. These trees are especially important for timber trade and are therefore subject to logging. Philippine dipterocarp forests are quite tall and dense reaching 45-65 m, with three canopy layers in the lowlands. The canopy heights of mature forests are uneven. Lianas and bamboo are rare in the mature forests, but common in poorly developed evergreen forest. Ferns, orchids, and other epiphytic plants are found on the larger trees and the undergrowth is abundant.  

At higher elevation montane rainforests, there are only two canopy layers and the tree stature is lower. Oak and Laurel species become dominant with an even greater number of epiphytes. The tree buttresses are much less pronounced than the lowlands. Vines and lianas are abundant and tree ferns can reach 10 m high. As elevation increases, the decreasing temperature slows the decomposition of debris making the forest floor thick with humus. The montane forests are extremely valuable for the wide range of endemic species they support.  They also have an important role in preventing soil erosion and protecting water quality.

Of the 1,196 known species of amphibians, birds, mammals and reptiles in the country, nearly 46% are endemic. Among plants, the number is around 40% endemic. The Philippine islands have varying degrees of endemism. There is a positive correlation of increasing amount of endemic species, especially with non-flying species, and the amount of isolation of the island. Many species are endemic to single or a few islands. Some mammal species include Philippine Warty Pig (Sus philippensis), Philippine Flying Lemur (Cyanocephalus volans), Philippine brown deer (Cervus mariannus), Philippine Spotted Deer (Cervus alfredi), Asian Leopard Cat (Prionailurus bengalensis), Philippine Tarsier (Tarsius sychrita), Malay civet (Viverra tangalunga), and Common Palm Civet (Paradoxurus hermaphroditus). Notable bird species are Philippine Cockatoo (Cacatua haematuropygia), Green Racquet-tail (Prioniturus luconensis), Isabela Oriole (Oriolus isabellae), 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) and Cebu Flowerpecker (Dicaeum quadricolor).

A few notable critically endangered species include: the country’s national bird-the Philippine Eagle (Pithecophaga jefferyi), a dwarf buffalo- the Tamaraw (Bubalus mindorensis), and the Philippine Crocodile (Crocodylus mindorensis) which is the most threatened of all crocodiles. All of these species are strictly endemic. Many other species are endangered or threatened in these rainforests, and habitat destruction is not the only reason. The pet trade in the Philippines has had a tremendous negative impact on certain species, especially for the Philippine Cockatoo and the Asian Leopard Cat.

Rainforest once covered 95% of the Philippines islands. Currently only about 6 to7% of the original old-growth, closed-canopy forest remains with only 3% remaining in the lowland regions. The Palawan rainforests are more intact than any other region in the Philippines, but are still under great pressure especially from logging interests. In addition to logging, the major threats include expanding rural population, mining, agricultural fires, and collection of fuelwood.

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