Luzon rain forests

TheLuzon rain forestis atropical moist broadleaf forestecoregionon the island ofLuzon. Luzon is the largest island in thePhilippines, and the Luzon rain forest is the most extensive rainforest ecoregion of the country. The ecoregion includes thelowlandsof Luzon and neighboring islands below 1000 meters elevation. Very little of the original rainforest remains, and the status of this area iscritical/endangered.
The Luzon rain forests encompass about 95,571 square kilometers (36,900 sq mi) out of the 109,965 sq kilometers (42,458 sq mi) of the total area of the island of Luzon.Luzon is the largest and northernmost major island of thePhilippines, located in the westernPacific Ocean. TheBatanesandBabuyan Islandsto the north,CatanduanesandPolillo Islandsto the east, andMarinduqueto the southwest are considered a part of the Luzon rain forests ecoregion.
TheLuzon montane rain forestsecoregion covers areas of the Sierra Madre, Zambales Mountains, and northern Cordillera Central above 1000 meters elevation. TheLuzon tropical pine forestscover the central Cordillera Central above 1000 meters elevation.
Luzon has never been connected to mainlandAsia. At least 15 million years ago, friction between theAustralianandAsiantectonic platesand volcanic activity created parts of the Luzonhighlands, which over the next 10 million years morphed into their modern form.This long period ofisolationand complex internalgeographyis a primary cause for the greatbiodiversityand high degree ofendemismfound on the island of Luzon.
During theIce ages, sea levels were up to 120 meters lower than at present. Ice-ageGreater Luzonconnected Luzon with Catanduanes, Marinduque, the Polillo Islands, and several smaller neighboring islands. The ice-age land bridges allowed the animals and plants of these now-separate islands to mix, which made them part of the same ecoregion.
In 2005, evidence for human occupation in northern Luzon since at least 25,000 years ago, was found inCallao Cave.Evidence includedchertflake tools, charredparenchymatoustissues, starch grains, grasses, andMoraceaephytolith.The possibility ofhunter-gathererssubsisting inHolocenetropical rain forestswithout support fromagriculturalistswas debated, based on the patchy andseasonalresources.Wild forest animals are lean and lacking incalorie-richfat.
However, hunters and gatherers may have managed by strategizing and moving to correspond to the shifting food resources.Information on skeletalmorphologyanddietis merely speculative as no human remains were recovered from this period. This idea is supported by the Sierra MadreAgtaof the recentethnographicpast who would plan their movements based on the seasons and available resources; they hunted in the montane forest during therainy seasonand in the lowland forest during thesummer.Most of their food supply came fromfishing,shellfishgathering, wildyams,nuts, andCaryotapalms.
In the same cave two years later, in 2007, the same scientist found ametatarsalbone dated to at least around 67,000 years ago, which is speculated to possibly be ofHomo sapiensorigin. The bone (Right MT3 – the small bone from the end of the middle toe of the right foot) has been identified as belonging to a species of the genusHomo. To tell if the bone belongs to an ancientanatomically modern human, askullormandiblefrom the specimen is needed. Thisfossilizedremaining fromCallao Caveis referred to asCallao Man.
DuringWorld War II, theJapaneseinvaded thePhilippines, and a small band of theCommunist Party of the Philippines(CPP)activistsused the dense mountainjunglesand vastswampsof the Luzon rainforest for protection.Thecommunistactivists established a base of operations in the nearbyMt. Arayatand theCandaba Swamp.These activists launched small yet annoying attacks against the Japanese.On December 10, 1941, CPP leaders issued amanifestovowing their support for the anti-Japanese efforts of theCommonwealthand theUnited States, and urging the peasants to support this united anti-Japanese front.Resulting was the organization of theHukbalahap, an acronym for the Hukbong Bayan Laban sa Hapon (the Anti-Japanese Army), in a small lowland forest clearing near Mt. Arayat on March 29, 1942, by the merging of the CPP with the remainingsocialistand peasant organizations of Luzon.
The rainforest of the lowlands encompass all areas below 1,000 metres (3,300 ft) inelevation.Much of the lowland rainforest has been destroyed by humandeforestationactivities.
Dipterocarptrees with widebuttressesdominate this area.These trees are massive, growing up to 60 metres (200 ft) tall with diameters between 1–2 metres (3.3–6.6 ft).Vatica pachyphyllais acritically endangeredtree speciesendemicto the ecoregion.
The mature lowland forests tend to have an unevencanopyheight.Rattansandlianasgrow in theunderstory, receiving the light they need to thrive through areas of disturbance.There is generally a large amount ofherbaceousundergrowth, withepiphyticfernsandorchidsgrowing on the thickbranchesof tall trees.
Above 1,000 metres (3,300 ft) elevation, the Luzon rain forests transition to theLuzon montane rain forestsecoregion. Montane rain forests are found in the Northern and SouthernSierra Madre, Mt. Sapacoy, Mt. Magnas, and Mt. Agnamala in the northernCordillera Centralhighlands, and in theZambales Mountainsin the west. In the south of the island, enclaves of montane forest can be found on severalvolcanicand non-volcanicmountainsthat exceed meters elevation. The volcanic mountains includeMt. Makiling,Mt. Banahaw,Mt. Isarog,Mayon Volcano, andBulusan Volcano.
In some areas, annualrainfallcan be about quadruple what the lowland rainforests receive (as high as 10,000 mm).The Sierra Madres have very mildseasons, with a slightdry periodbetween December and April. TheZambales Mountainsand northernCentral Cordillerahighlands are more strongly seasonal with a longer dry period and slightly less rainfall generally.
Thedipterocarptrees of the lowlands are gradually replaced byoakandlaurel forestspecies with increasing altitude.The forests generally have less undergrowth and become shorter in stature as altitude increases.With the decreasing temperature from increasing altitude,decompositionis slowed and results in a forest floor thick withhumus.
In the montane forests,epiphytes,vines, andmoss-covered branches are very common.The highest altitudes of montane forests are called upper montane forest, orelfin forest, and are more extreme: trees are shorter in stature, and tree branches are so thick with moss andorganic materialthat they can sustain aerial plants that are not typicallyepiphytes.Manyendemicanimal species reside in the thick, matty soil of the upper montane forests.
In fact,species richnessis greatest along the highest elevations of the montane rainforests of Luzon.Areas with the greatest levels of endemism are reported to be theCordillera Centralhighlands, theSierra Madre, theZambales Mountains, andhighlandson theBicol Peninsula.
There are at least 31endemicspecies ofmammalson the island ofLuzon.Sixty-eight percent of all known native non-flying mammals are endemic to the area (23 of 34).
ThePhilippine eagle(Pithecophaga jefferyi), one of the largesteaglesin the world, is found primarily in the Sierra Madre of Luzon.Primary lowland rainforests of the Philippines have been heavilydeforested, and the Philippine eagle needs this area to breed, as well as nesting in large trees and hunting within the trees.The eagle is restricted to the islands ofLuzon,Samar,Leyte, andMindanao.Attempts forcaptive breedinghave been unsuccessful and it is estimated that less than 700 individuals remain.
Often called Myer’s snake in honor of Dr.George S. Myers, the genusMyersophisrepresented only by the speciesalpestris. It is asnakefound only in the northern highlands of Luzon.
About sixty-eight percent of allnativereptilesareendemicto the area (about 160 of 235).ThePhilippine crocodile,Crocodylus mindorensis, is afreshwater crocodilethat is considered the most threatened crocodile in the world and is endemic to the Philippines; it is only found inMindanao,Negros, andLuzon.Wild populations in 1982 totaled somewhere between 500 and 1000 individuals.In 1995, this number decreased to a mere 100 individuals.The discovery of a population of this crocodile in the Northern Sierra Madre on Luzon gives hope for itsconservation.Active in the conservation ofCrocodylus mindorensisis the Crocodile Rehabilitation Observance and Conservation (CROC) Project of the Mabuwaya Foundation.
The Sierra Madres give hope to many other threatened animals by providing one of the largest areas of intact rainforest in the Philippines thereby maintaining the naturally high level ofbiodiversity.Many species ofthreatenedbirdsare found in this location.
A 2017 assessment found that 9,994  km, or 11%, of the island is inprotected areas.Protected areas in the ecoregion include: