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Introduction
VEGETATION OF THE PHILIPPINE ISLANDS
by Dr. Edwino S. Fernando
Department of Forest Biological Sciences, and
the Makiling Botanic Gardens, University of the Philippines
at Los Baiios, College, 4031 Laguna, Philippines
The Philippine Islands lie slightly above the equator on the western edge of the Pacific Ocean.
They are spread in a north-south orientation between 21" and 5" N latitude and between 116"
and 126"E longitude, stretching some 1839 km between Taiwan to its north, and Borneo and
Sulawesi to its south. The islands form part of a phytogeographical region known as Malesia
that also includes the Malay Peninsula, Singapore, Sumatra, Borneo, Java, the Lesser Sunda
Islands, Sulawesi, Moluccas and New Guinea (Fig. 1).
The Philippine archipelago comprises more than 7000 islands of varying sizes and distance
apart. About 460 of these islands have an area of at least 2.5 km2. The total land area is
nearly 300 000 km2 just slightly more than one-third of the area of New South Wales. About
two-thirds of the Philippine area is represented by the two largest islands, Luzon and Mindanao
(Fig. 2; Table -). The remaining one-third is shared by the other islands. Four of these, viz.
Samar, Negros, Panay and Palawan have areas above 11 000 km2. Seven islands have areas
between 1000 and 10 000 km2 while some 24 others have areas between 100 and 1000 km2.
The topography of the islands can be characterized as generally mountainous. There are at
least 11 mountains with summits reaching from 1700 m to more than 2900 m. The highest
mountain peak is that of Mt Apo (2929m) on Mindanao, closely followed by Mt Pulog (2924 in)
on Luzon. The other islands with mountain peaks above 2000 m are Mindoro, Panay, Negros
and Palawan. The great mountain ranges are the Cordillera, Caraballo and the Sierra Madre,
all on Luzon.
The tropical climate of the Philippine Islands is largely governed by the southwest and
northeast monsoons with two main seasons: the wet (typhoon) season from June to October
and the dry season from November to May. The mean monthly temperature at sea levels for
the warmer months (March-October) ranges from about 26°C to 28°C and for the cooler
months (November-February) from 25°C to 26°C. The mean annual rainfall varies
considerably in different parts of the archipelago ranging from 900 mm to 4500 mm. The
western parts of the archipelago, which are in the lee of many mountain ranges, are generally
drier and seasonal in character. The eastern parts receive much nf the rainfall and are
perhumid. Greatest precipitation occurs when tropical storms (typhoons) cross the archipelago
from the Pacific.
Palaeogeography and Vegetation History
The Philippine lslands are regarded as having a complex geological history (McCabe et al.
1982). Indeed, recent palaeogeographic models consider the archipelago to be an
assemblage of ophiolite terranes, island-arc, ocean-basin, and continental fragments of
different origins and ages (Roeder 1977; Hamilton 1979; Audley-Charles 1981; McCabe et al.
1982, 1987; Wolfe 1983; Karig et al. 1986; Mitchell et al. 1986; Geary et al. 1988). This
assemblage is believed to have been formed during the Tertiary (Geary et al. 1988). The
western parts of