Vanuatu rain forests

The Vanuatu rain forests are tropical and subtropical moist broadleaf forests ecoregion which includes the islands of Vanuatu, as well as the Santa Cruz Islands group of the neighboring Solomon Islands. It is part of the Australasian realm, which includes neighboring New Caledonia and the Solomon Islands, as well as Australia, New Guinea, and New Zealand.[2]

Vanuatu rain forests
Neslep River on Efate, Vanuatu
Ecology
RealmAustralasian realm
Biometropical and subtropical moist broadleaf forests
Geography
Area12,281 km2 (4,742 sq mi)
CountriesVanuatu and Solomon Islands
Provinces of Solomon IslandsTemotu Province
Conservation
Conservation statusCritical/endangered
Global 200Solomons-Vanuatu-Bismarck moist forests
Protected515 km² (4%)[1]

Geography

The islands were created by the subduction of the northward-moving Australian Plate beneath the Pacific Plate. The surface geology of Vanuatu consists mostly of Pliocene-Pleistocene volcanic rocks and uplifted coral limestone. The Santa Cruz Islands have areas of both uplifted limestone and volcanic ash over limestone. The oldest rocks in Vanuatu are 38 million years old. The Santa Cruz islands are younger, with the oldest rocks less that 5 million years old.[2]

Most of the islands are low-lying. The largest island is Espiritu Santo (3,955.5 km2). The highest peak is Mount Tabwemasana on Espiritu Santo (1,879 m). Nendö is the largest of the Santa Cruz Islands. The highest peak in the Santa Cruz islands (924 m) is on Vanikoro.

Climate

The ecoregion has a tropical wet climate. The windward southeastern sides of the islands receive more rainfall. The leeward northwestern slopes of islands have a distinct dry season between April and October. Tropical cyclones occur regularly.[2]

Flora

The natural plant communities on the islands include lowland rain forest, montane rain forest, seasonal forest and scrub, coastal strand, mangroves, vegetation on recent volcanic rocks, and secondary vegetation.[2]

Lowland rain forest occurs on the southeastern, or windward, sides of Vanuatu's islands. There are several lowland rain forest types. Complex forest scrub densely covered with lianas is the most widespread forest type on the larger northern islands. Other types include high- and medium-stature forests, alluvial and floodplain forests, and mixed-species forests without conifers. Agathis-Calophyllum lowland forest is found on the southern islands of Erromango and Aneityum.[2]

Lowland rainforest is the predominant plant community on the Santa Cruz Islands, and has some differences from the lowland rain forests on the islands further south. Typical species include Campnosperma brevipetiolatum, Calophyllum vitiense, Gmelina salomonensis, Parinari corymbosa, Paraserianthes falcataria, Pterocarpus indicus, and Endospermum medullosum. There is no well-developed montane forest, but the trees Metrosideros ornata, Syzygium spp., and the conifers Agathis and Dacrydium elatum, which elsewhere are montane species, occur in the islands' lowland forests.[2]

Montane rain forests extent from as low as 500 meters elevation up to patches of stunted cloud forest on the islands' highest peaks. They include the conifers Agathis and Podocarpus, together with broadleaf evergreen trees Metrosideros ornata, Syzygium spp., Weinmannia spp., Geissois spp., Quintinia spp., and Ascarina spp.[2] The tree ferns Cyathea and Dickinsonia are common, and the endemic palm Clinostigma harlandii is found on the islands Ambrym, Aneityum, and Erromango.

Seasonal forest, scrub, and grassland grow on the leeward sides of the islands. Semideciduous Kleinhovia hospita-Castanospermum australe forests are a transition between rain forest and dry forest, and include some rain forest species. Forest of gaiac (Acacia spirorbis) is found in drier areas, with a canopy up to 15 meters high. Thickets and savannas of the introduced tree Leucaena leucocephala and grasslands are also found on the leeward sides of the islands.[2]

Littoral forests include Casuarina equisetifolia, Pandanus spp., Barringtonia asiatica, Terminalia catappa, Hernandia spp., and Thespesia populnea.[2]

Coastal mangrove forests are found on some islands, and contain species of Rhizophora, Avicennia, Sonneratia, Xylocarpus, and Ceriops.[2]

Fauna

Bats are the only native mammals in the ecoregion. There are twelve species – four megabats and eight microbats – five of which are endemic. The four megabats – Vanuatu flying fox (Pteropus anetianus), Temotu flying fox (Pteropus nitendiensis), Vanikoro flying fox (Pteropus tuberculatus), and Banks flying fox (Pteropus fundatus) – are endemic. Native microchiroptera include the Fijian blossom bat (Notopteris macdonaldi), Fijian mastiff bat (Chaerephon bregullae), Pacific sheath-tailed bat (Emballonura semicaudata), large-footed bat (Myotis adversus), little bent-wing bat (Miniopterus australis), great bent-winged bat (Miniopterus tristis), Temminck's trident bat (Aselliscus tricuspidatus), and fawn leaf-nosed bat (Hipposideros cervinus). The endemic Nendo tube-nosed fruit bat (Nyctimene sanctacrucis) is presumed extinct.[2]

There area 79 native bird species in Vanuatu. Fifteen species are endemic – Vanuatu scrubfowl (Megapodius layardi), Santa Cruz ground-dove (Gallicolumba sanctaecrucis), Tanna ground-dove (Gallicolumba ferruginea), Tanna fruit-dove (Ptilinopus tannensis), Baker's imperial pigeon (Ducula bakeri), palm lorikeet (Charmosyna palmarum), chestnut-bellied kingfisher (Todirhamphus farquhari), Vanikoro monarch (Mayrornis schistaceus), buff-bellied monarch (Neolalage banksiana), black-throated shrikebill (Clytorhynchus nigrogularis), Vanikoro flycatcher (Myiagra vanikorensis), Santa Cruz white-eye (Zosterops santaecrucis), yellow-fronted white-eye (Zosterops flavifrons), Sanford's white-eye (Woodfordia lacertosa), New Hebrides honeyeater (Phylidonyris notabilis), royal parrotfinch (Erythrura regia), Polynesian starling (Aplonis tabuensis), rusty-winged starling (Aplonis zelandica), and Mountain starling (Aplonis santovestris).[2] The ecoregion corresponds to the Vanuatu and Temotu endemic bird area.[3]

  • "Vanuatu rain forests". Terrestrial Ecoregions. World Wildlife Fund.
  • Vanuatu and Temotu endemic bird area BirdLife International.

References
  1. Eric Dinerstein, David Olson, et al. (2017). An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm, BioScience, Volume 67, Issue 6, June 2017, Pages 534–545; Supplemental material 2 table S1b.
  2. "Vanuatu rain forests". Terrestrial Ecoregions. World Wildlife Fund.
  3. BirdLife International (2020) Endemic Bird Areas factsheet: Vanuatu and Temotu. Downloaded from http://www.birdlife.org on 02/06/2020.

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