The rainforest of the lowlands encompass all areas below in
elevation. These trees are massive, growing up to tall with diameters between . The mature lowland forests tend to have an uneven
canopy height.
Rattans and
lianas grow in the
understory, receiving the light they need to thrive through areas of disturbance. There is generally a large amount of
herbaceous undergrowth, with
epiphytic ferns and
orchids growing on the thick
branches of tall trees.
Montane forests mountain range. Above elevation, the Luzon rain forests transition to the
Luzon montane rain forests ecoregion. Montane rain forests are found in the Northern and Southern
Sierra Madre, Mt. Sapacoy, Mt. Magnas, and Mt. Agnamala in the northern
Cordillera Central highlands, and in the
Zambales Mountains in the west. In the south of the island, enclaves of montane forest can be found on several
volcanic and non-volcanic
mountains that exceed meters in elevation. The volcanic mountains include
Mt. Makiling,
Mt. Banahaw,
Mt. Isarog,
Mayon Volcano, and
Bulusan Volcano. In some areas, annual
rainfall can be about quadruple what the lowland rainforests receive (as high as 10,000 mm). The Sierra Madres have very mild
seasons, with a slight
dry period between December and April. The
Zambales Mountains and northern
Central Cordillera highlands are more strongly seasonal with a longer dry period and slightly less rainfall generally. The
dipterocarp trees of the lowlands are gradually replaced by
oak and
laurel forest species with increasing altitude. The forests generally have less undergrowth and become shorter in stature as altitude increases. With the decreasing temperature from increasing altitude,
decomposition is slowed and results in a forest floor thick with
humus. In the montane forests,
epiphytes,
vines, and
moss-covered branches are very common. The highest altitudes of montane forests are called upper montane forest, or
elfin forest, and are more extreme: trees are shorter in stature, and tree branches are so thick with moss and
organic material that they can sustain aerial plants that are not typically
epiphytes. Many
endemic animal species reside in the thick, matty soil of the upper montane forests. In fact,
species richness is greatest along the highest elevations of the montane rainforests of Luzon. Areas with the greatest levels of endemism are reported to be the
Cordillera Central highlands, the
Sierra Madre, the
Zambales Mountains, and
highlands on the
Bicol Peninsula. ==Fauna==