Western Java rainforests

Ecoregions (main)

Published: May 8, 2014, 2:43 pm

Topics:

Ecoregions (main) Conservation Biology (main) Rainforests (main) Biodiversity (main) Ecology (main) Geography (main)

Ujung Kulon National Park, Java, Indonesia (Photograph by John Morrison)

WWF Terrestrial Ecoregions Collection

The Western Java rainforests are found on one of the most active volcanic islands in the world. Once the home of the extinct Javan Tiger (Panthera tigris sondaicus), these forests still contain one of the two remaining populations of one of the world's most threatened mammal species, the critically endangered Javan Rhinoceros (Rhinoceros sondaicus). Unfortunately, only about 5 percent of the original habitat of this ecoregion remains.

Location and General Description

This ecoregion represents the lowland moist forests (less than 1000 metres in elevation) of western Java, Indonesia. Based on the Köppen climate zone system, this ecoregion falls in the tropical wet climate zone, although as one moves eastward on Java there is increasing seasonality of precipitatio. Java probably did not exist before the Miocene (24 million years before present).

Truly born of fire, the island of Java is the result of the subduction and remelting of the Australian-Indian Ocean tectonic plate beneath the Eurasian tectonic plate at the Java trench. The melted crust has risen as volcanoes and, along with subsequent sedimentation, created Java. Therefore, the surface geology consists of Tertiary and Quaternary volcanics, alluvial sediments, and areas of uplifted coral limestone. Twenty of the volcanoes on Java and Bali have been active in historic times, and they are among the most active volcanic islands in the world. During previous ice ages, when sea levels were much lower, Java was connected to Sumatra, Borneo, and the rest of the Asian mainland.

The natural forests in the lowlands of western Java once included several forest subtypes, including extensive evergreen rainforest, semi-evergreen rainforest, moist deciduous forest along the northern coastal zone, and dry deciduous forest, also along the northern coast of the island. The differences are mostly related to the seasonality of rainfall. There are also small areas of azonal limestone and freshwater swamp forests. No single tree family dominates the forests of Java, as is the case with the dipterocarps in Sumatra and Borneo.

Source: WWF

The most common plant species (Biodiversity) in the rainforests of Java are Artocarpus elasticus (Moraceae), Dysoxylum caulostachyum (Meliaceae), langsat Lansium domesticum (Meliaceae), and Planchonia valida (Lecythidaceae). Semi-evergreen rain forest differs from evergreen rain forest by being slightly more seasonal, with two to four dry months each year.

Java's deciduous forests generally are lightly closed, with few trees exceeding 25 meters (m). Borassus and Corypha palms are good indicators of the seasonal climates that generate deciduous forests in the region. Moist deciduous forests have 1500 to 4000 milimeters (mm) of rainfall annually, with a four- to six-month dry season. Dry deciduous forests have less than 1,500 mm of annual rainfall and more than six dry months. Common lowland deciduous trees found in eastern Java and Bali are Homalium tomentosum, Albizia lebbekoides, Acacia leucophloea, A. tomentosa, Bauhinia malabarica, Cassia fistula, Dillenia pentagyna, Tetrameles nudiflora, Ailanthus integrifolia, and Phyllanthus emblica. Many herbaceous plants are confined to the deciduous forests.

Limestone forests on Java have basal areas similar to those of other lowland forest types and apparently contain no plant endemics, but because they often grow on steep slopes of shallow soils, their growth pattern is affected. Limestone forests are found on Mt. Cibodas, Nusu Barung, Padalarang, and Nusa Penida.

Patches of freshwater swamp forest found throughout the ecoregion are relatively poor in species (Biodiversity). Rawa Danau, Banten in west Java is the largest remaining area of swamp forest in Java and Bali, and it contains many tree species now nearly extinct elsewhere in Java, such as Elaeocarpus macrocerus, Alstonia spathulata, wild mango (Mangifera gedebe), and Stemonurus secundiflora. Other rare plants include the sedge Machaerina rubiginosa, the aroid Cyrtosperma merkusii, and floating water plants such as Hydrocharis dubia and water chestnut (Trapa maximoviscii).

Biodiversity Features

Large flying fox (Pteropus vampyrus), Indonesia (Photograph by Marty Fujita)

The overall richness and endemism of this ecoregion are moderate compared with those of other ecoregions in Indo-Malaysia.

The ecoregion harbors 101 mammal species, including five endemics and near endemics (Table 1). The larger of the two known populations of the critically endangered Javan rhinoceros (Rhinoceros sondaicus) is found in the extreme western part of the ecoregion, in Ujung Kulon National Park. The Javan gibbon (Hylobates moloch) is also critically endangered. Other species of conservation significance include the globally threatened surili (or Java) leaf monkey (Presbytis comata), fishing cat (Felis viverrina), wild dog (Cuon alpinus), Javan warty pig (Sus verrucosus), banteng (Bos javanicus), and slow loris (Nycticebus coucang). The Javan subspecies of the yellow-throated marten (Martes flavigula robinsoni) and leopard on Java (Pantera pardus melas) are also considered endangered.

Table 1. Endemic and Near-Endemic Mammal Species.
Family	Species
Rhinolophidae	Rhinolophus canuti
Molossidae	Otomops formosus
Hylobatidae	Hylobates moloch
Suidae	Sus verrucosus
Muridae	Sundamys maxi
An asterisk signifies that the species' range is limited to this ecoregion.

More than 350 bird species are known to occur in the ecoregion, including 9 endemics and near endemics (Table 2). This ecoregion overlaps with two Endangerd Bird Areas (EBAs): Java and Bali forests and Javan coastal zone. These two EBAs contain a total of thirty-seven restricted-range birds, including the extinct Javanese lapwing (Vanellus macropterus). Nine of these restricted-range birds are found in this ecoregion of lowland west Java (including the extinct lapwing).

Table 2. Endemic and Near-Endemic Bird Species.
Family	Common Name	Species
Accipitridae	Javan hawk-eagle	Spizaetus bartelsi
Charadriidae	Javan plover	Charadrius javanicus
Charadriidae	Sunda lapwing	Vanellus macropterus
Cuculidae	Sunda coucal	Centropus nigrorufus
Zosteropidae	Javan white-eye	Zosterops flavus
Timaliidae	White-breasted babbler	Stachyris grammiceps
Timaliidae	White-bibbed babbler	Stachyris thoracica
Timaliidae	Grey-cheeked tit-babbler	Macronous flavicollis
Timaliidae	Crescent-chested babbler	Stachyris melanothorax
An asterisk signifies that the species' range is limited to this ecoregion.

The forests of west Java are more species-rich for plants than the rest of the island, with more than 3,800 species (Biodiversity), including two endemic genera. These forests harbor two species of the giant insectivorous Rafflesia (R. rochussenii and R. patma).

Current Status

Only about 5 percent of the original habitat of this ecoregion remains. There are thirty-three protected areas that cover 3,045 square kilometers (km²⁾ (7 percent), but most of the protected areas (twenty-eight) are small (less than 100 km²) (Table 3). The largest, Ujung Kulon National Park, is significant for its Javan rhinoceros population.

Table 3. WCMC (1997) Protected Areas That Overlap with the Ecoregion.
Protected Area	Area (km2)	IUCN Category
Pulau Sangiang	20	DE
Gunung Tukung Gede	50	I
Muara Angke	30	I
Rawa Danau	70	I
Carita	30	V
Yanlapa	10	I
Depok	20	I
Tanjung Pasir	20	?
Mawuk	20	?
Gunung Karang	50	?
Jayabaya	40	?
Muara Gembong	30	?
Muara Bobos	90	?
Tanjung Sedari	90	?
Muara Cimanuk	80	?
Ujung Kulon	1,120	II
Cikepuh	140	IV
Peson Subah I, II	10	I
Ulolanang Kecubung	30	I
Unnamed	40	?
Gunung Unggaran	70	?
Ciogong	40	?
Salatri	30	?
Bojong Larang Jayanti	20	I
Gunung Selok	30	V
Leuwang Sancang	110	I
Pasir Salam	70	?
Nusakambangan	200	?
Gunung Kendeng	30	?
Cikencreng	30	?
Telaga Bodas	5	?
Telogo Ranjeng	20	I
Gunung Pangasaman	400	?
Total	3,045

Java is one of the most densely populated islands in the world, so it is not surprising that very little natural habitat remains here. Anthropogenic fires are common, and over the centuries burning has resulted in monospecific stands of fire-resistant species, usually Tectona grandis. In many annual cropping systems, soils are left exposed during critical periods, resulting in extensive erosion. Illegal farming and felling even within protected areas are widespread, and an important timber tree Altingia excelsa has been nearly eliminated from the lowland forests. In freshwater swamp forests, the exotic Mimosa pigra has the potential to become a very serious pest because it is fire-resistant and capable of forming impenetrable thickets. Plans to construct a dam at the outlet of the Cidanau will destroy Rawa Danau, the only remaining extensive area of freshwater swamp in Java.

Types and Severity of Threats

The threats that have degraded or destroyed most of this ecoregion in the past still threaten the remaining forest fragments. Political instability will continue to contribute to rampant destruction of these forests as existing environmental laws are routinely ignored and not implemented.

Justification of Ecoregion Delineation

MacKinnon included the islands of Java and Bali in biounit 22 (with three subunits). Western Java is wetter than the eastern half of the island, and the forests are richer in species. There are also floristic differences between the lowland and montane vegetation in Java and Bali. Therefore, using MacKinnon's subunit boundary, we delineated the Western Java Rain Forests to represent the moister evergreen forests to the west and the Eastern Java-Bali Rain Forests to represent the drier, less species-rich forests of eastern Java and Bali. However, we also extracted the montane forests into distinct ecoregions-Western Java montane rainforests and Borneo Montane Rain Forests -using the 1,000-m elevation contour of a Digital Elevation Model (DEM).

Disclaimer: This article contains information that was originally published by the World Wildlife Fund. Topic editors and authors for the Encyclopedia of Earth have edited its content and added new information. The use of information from the World Wildlife Fund should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

Citation

Fund, W. (2014). Western Java rainforests. Retrieved from http://editors.eol.org/eoearth/wiki/Western_Java_rainforests