Included here is the island of Java, one of the Great Sunda Islands archipelago of Indonesia. Mountains extend along an east-west spine with over 30 mountain peaks. These have all been active volcanoes the highest of which is Mount Semeru (3676 m).

Javan Mixed Montane Rainforest

On Mount Gede and Mount Pangrango between altitudes of about 1400-2900 m the mountain forests are distinctly different from those of the lowlands. These forests are not homogenous and show a degree of variation with altitude. However, at about 2400 m on Mount Pangrango they have a stratification comprising four layers including the ground layer. The first layer or canopy ranges from about 15-20 m in height and typically includes Acronodia punctata, Myrsine affinis, Polyosma ilicifolia and Symplocos sessilifolia. Altringia excelsa, Schima wallichii and the endemic or near endemic Castanopsis javanica (Fagaceae) may also be present but these tend to be more abundant at slightly lower parts of the montane forest. In fact, Altringia excelsa dominates parts of the lower montane forest in the Mt Gede-Pangrango National Park. A number of these taller species, particularly Polyosma ilicifolia are also common in the second layer, which ranges in height from 5-15 m. Other species include Vaccinium laurifolium, Viburnum coriaceum and there may be endemic or near endemic species such as Ehretia javanica (Boraginaceae), Helicia javanica (Proteaceae), Lithocarpus indutus (Fagaceae), Symplocos costata (Symplocaceae) and Neolitsea javanica (Lauraceae). The third layer contains small trees and shrubs up to about 5 m high and typically including the endemic Ardisia javanica (Myrsinaceae). The endemic tree fern Cyathea crenulata (Cyatheaceae) may also be present while other endemic or near endemic trees and shrubs are Endiandra javanica (Lauraceae), Euonymus javanica (Celastraceae) and Olea javanica (Oleaceae).  Climbers are well represented and include vines like the endemic Schisandra elongata (Schisandraceae), although lianas seem to be relatively few in numbers but include the endemic Lonicera javanica (Caprifoliaceae). Among the rich epiphytic flora the attractive fern Asplenium nidus is frequently encountered, but there is also a rich diversity of other ferns and orchids. Among the latter are Appendicula ramosa, Bulbophyllum uniflorum, Cyperorchis rosea, Liparis pallida and Malaxis blumei. At ground level the typical herbaceous species include Myriactis javanica, Ranunculus javanicus and Swertia javanica, but none of these despite these names are endemic to Java. However, other possibly less common herb-layer species such as Amomum hochreuteneri (Zingiberaceae) and Zingiber odoriferum (Zingiberaceae) are endemic.

Javan Podocarp Montane Moss Forest

At altitudes exceeding 1700 m podocarps become the dominant tree species. On Java’s Mount Gedeh three species occur: Podocarpus amara, P. imbricata and P. neriifolia. These are the only conifer and, in fact, the only gymnoperms indigenous to Mt Gedeh. The transformation to podocarps occurs very suddenly and people have wondered at what climatic factors could exist to produce such a marked change. Other large trees include Engelhardtia serrata and Schima noronha, while smaller trees are Elaeopcarpus acronodia, Meliosma nervosa, Michelia montana, Macropanax dispermum and Pygeum latifolium. All of these trees are covered in a luxuriant growth of bryophytes the most abundant of which is the festooning Papillaria fuscescens. Other epiphytes include an abundance of ferns, such as the attractive bird’s nest fern Asplenium nidus, and orchids like the endemic Schoenorchis juncifolia (Orchidaceae). The forest floor tends to be quite open with a luxuriant growth of terrestrial ferns such as the giant Polypodium nigrescens. Another feature of these forests are numerous small bog land areas in which the purplish-red pitcher plant Nepenthes melamphora frequently occurs. Among the abundant lianas Fagara scandens is particularly conspicuous. Its huge stubby spines give it a nasty appearance. Other climbers include the aroid Epipremnum pinnatum.

Javan Casuarina Montane Forest

Forest dominated by the endemic Casuarina junghuhniana (Casuarinaceae) occur in upland areas east of Mt Lawu on the border of central and east Java. This species and the associated Podocarpus imbricatus are pioneer species colonizing areas that have been stripped of their vegetation by disturbance such as landslips, volcanic ash falls or fires. However, neither of these will regenerate under a closed canopy and so usually have a limited existence. Nevertheless, unlike most pioneer species Casuarina junghuhniana is long-lived and can grow to a great height  (up to 45 m). At altitudes over 1400 m, it often forms monospecific stands and can grow at altitudes up to 3000 m. Impressive forest can be seen, for example, on Mt Argapura. Beneath the canopy a variety of shrubs occur include the large green Euphorbia javanica, which can form dense carpets. However, despite its name it is not endemic to Java. Other ground layer species include the fearfully armed nettle Girardinia palmata. Its poisonous spines up to 0.5 cm can inflict a painful sting. Endemic taxa include Alchemilla villosa (Rosaceae), Dioscorea vilis (Dioscoreaceae), Pimpinella prvatjan (Apiaceae), Plectranthus steenisii (Lamiaceae) and Styphelia javanica (Epacridaceae). Cynoglossum javanicum (Boraginaceae) can also be found, but despite its name, it is not endemic and also occurs on Sumatra. On Flores these forests support the local endemic Rhododendron renschianum (Ericaceae), while on Timor they support the local endemic aerial parasite Dendrophthoe timorana (Loranthaceae), which parasitizes both Albizia and Casuarina. On some of the volcanoes there are so-called ‘sand seas’ of virtually unvegetated ash, mainly because it retains very little moister. In the Rujak area, however, short stands of Casuarina have managed to become established in these inhospitable areas. Associated species include various tussock forming grasses and the white, hairy-flowered endemic Styphelia javanica (Ericaceae). 

Javan Alpine Vaccinium Woodland Zone

Between altitudes ranging from about 8000-9000 ft on Java’s Mount Gedeh and Mount Pangerango is a zone largely dominated by species of Vaccinium. Five species occur: Vaccinium coriaceum, V. ellipticum, V. laurifolium, V. lucidum and V. varingiaefolium. This particular group of Vaccinium species has become remarkable polymorphic and can develop as trees, shrubs and lianas. Vaccinium varingiaefolium is particularly versatile having been recorded as a tree, shrub, liana and can grow both terrestrially and epiphytically. However, the trees at this elevation rarely grow to more than about 20 m in height and tend to have knarled, twisted trunks. A tree of some interest is Acer niveum, which can grow near to the summit of these mountains, is the only maple on Java. Other trees include Astronia spectabilis, Eury japonica, Polyosma ilicifolia and Rapanea avensis, although in some upper sections of this zone Vaccinium varingiaefolium occurs almost to the exclusion of other trees. Among the shrubs, Rododendron is a common colourful addition with the yellow flowers of R. cilium, red flowers of R. retusum and orange-red flowers of R. javanicum. Despite its name the latter species is not endemic to Java. Herb layer species include orchids such as Dendrobium hasseltii, the attractive Impatiens platypetala and the parasitic Balanophora elongata. The latter is curious plant with a short red flower-spike and parasitizes both Albizzia and Vaccinium. Other herb layer species are Viola serpens and the near endemic Ranunculus javanicus (Ranunculaceae). Epiphytes are numerous especially ferns of the genus Polypodium such as P. hirtellum, and there are many filmy ferns like the tiny Hymenophyllum paniculiflorum. Mosses are also abundant covering virtually every tree and vine.

References

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