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 than 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, also known as Santa Cruz, is the largest of the Santa Cruz Islands with an area of 519 km2. Vanikoro is 190 km2, and Utupua is 69 km2. The highest peak in the Santa Cruz islands (924 m) is on Vanikoro. Nendö reaches over 500 meters elevation, and Utupua 350 m. They are made mostly of basaltic volcanic rocks of Pliocene origin, less than 5 million years old. The southeastern lowlands of Nendö are composed of uplifted Pleistocene reef limestone.[6]
Smaller islands in the group include Tinakula (8 km2 and 800 meters elevation), a conical active stratovolcano 30 km north of Nendö, and the Reef Islands northeast of Nendö, composed of uplifted Pleistocene reef limestone and rising only 5 meters above sea level. The Duff Islands are a small chain with four main islands about 130 km northeast of Nendö, with a combined area of 14 km2 and which rise up to 300 m elevation. Tikopia (5 km2), Anuta (1 km2), and Fataka (5 km2) are small isolated islands east and southeast of Vanikoro.[6]
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]
In Vanuatu, 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 macrophylla and Dacrycarpus imbricatus, together with broadleaf evergreen trees Metrosideros vitiensis, Syzygium spp., Pterophylla 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.[2]Podocarpus vanuatuensis is a Vanuatu endemic, native to Aneityum and Erromango. Agathis silbae is endemic to the Cumberland Peninsula and Mount Tabwemasana, also known as Santo Peak, on the west coast of Espiritu Santo, from 450 to 760 meters elevation. It is a large emergent tree in lower montain rainforest on the wetter western and northwestern slopes of Espiritu Santo's central mountain range, with an average annual rainfall of about 4,500 mm. Associated trees include Calophyllum neo-ebudicum, Cryptocarya turbinata, Didymocheton sp., Myristica sp., and Podocarpus sp.[7]Metrosideros tabwemasanaensis is a tree endemic to the montane forests of Mount Tabwemasana.[8]
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]
The Pacific boa (Candoia bibroni), also known as Bibron’s bevel-headed boa, the Solomon Islands boa, or the Pacific ground boa (among several other names), is native to the island and surrounding region. It is unique among Boidae snakes for its “bevel” or “spade”-shaped snout, used for digging; perhaps the closest comparable species would be the Kenyan sand boa, which spends much of its time burrowing, where it will lie in wait to ambush its passing prey above.[citation needed]
The Solomon Islands rain forests are a terrestrial ecoregion covering the Solomon Islands archipelago.
The Santa Cruz Islands are a group of islands in the Pacific Ocean, part of Temotu Province of the nation of Solomon Islands. They lie approximately 250 miles to the southeast of the Solomon Islands archipelago. The Santa Cruz Islands lie just north of the archipelago of Vanuatu, and are considered part of the Vanuatu rain forests ecoregion.
The South Western Ghats montane rain forests is an ecoregion in South India, covering the southern portion of the Western Ghats in Karnataka, Kerala and Tamil Nadu at elevations from 1,000 to 2,695 m. Annual rainfall in this ecoregion exceeds 2,800 mm (110 in).
The Ogasawara subtropical moist forests is a terrestrial ecoregion which encompasses the Ogasawara Archipelago of Japan. The Ogasawara Archipelago lies in the Pacific Ocean south of Honshu, Japan's largest island, and north of the Marianas Islands. The ecoregion includes the Bonin Islands and Volcano Islands chains. The islands are volcanic in origin, and have never been linked to a continent. They are home to distinct plants and animals including many endemic species.
The East Melanesian Islands, also known as the Solomons-Vanuatu-Bismarck moist forests, is a biogeographic region in the Melanesia subregion of Oceania. Biogeographically, the East Melanesian Islands are part of the Australasian realm.
The Hawaiian tropical rainforests are a tropical moist broadleaf forest ecoregion in the Hawaiian Islands. They cover an area of 6,700 km2 (2,600 sq mi) in the windward lowlands and montane regions of the islands. Coastal mesic forests are found at elevations from sea level to 300 m (980 ft). Mixed mesic forests occur at elevations of 750 to 1,250 m, while wet forests are found from 1,250 to 1,700 m. Moist bogs and shrublands exist on montane plateaus and depressions. For the 28 million years of existence of the Hawaiian Islands, they have been isolated from the rest of the world by vast stretches of the Pacific Ocean, and this isolation has resulted in the evolution of an incredible diversity of endemic species, including fungi, mosses, snails, birds, and other wildlife. In the lush, moist forests high in the mountains, trees are draped with vines, orchids, ferns, and mosses. This ecoregion includes one of the world's wettest places, the slopes of Mount Waiʻaleʻale, which average 373 in (9,500 mm) of rainfall per year.
The São Tomé, Príncipe, and Annobón forests, also known as the São Tomé, Príncipe, and Annobón moist lowland forests, is a tropical moist broadleaf forest ecoregion that covers the islands of São Tomé and Príncipe, which form the island nation of São Tomé and Príncipe, as well as the island of Annobón, which is part of Equatorial Guinea.
The Temotu flying fox is a species of flying fox in the family Pteropodidae. It is endemic to the Solomon Islands. It is threatened by habitat destruction due to subsistence agricultural practices, as well as natural disasters such as tropical cyclones. Due to its imperiled status, it is identified by the Alliance for Zero Extinction as a species in danger of imminent extinction. In 2013, Bat Conservation International listed this species as one of the 35 species of its worldwide priority list of conservation.
The Solomon Archipelago is a terrestrial ecoregion and marine ecoregion in the Pacific Ocean. It includes the tropical ocean waters surrounding most of the Solomon Islands archipelago, and includes Bougainville Island and Buka Island of Papua New Guinea and their surrounding waters.
Vanikoro is an island in the Santa Cruz group, located 118 kilometres to the Southeast of the main Santa Cruz group. It is part of the Temotu Province of the Solomon Islands.
The Vanikoro white-eye is a species of bird in the family Zosteropidae. It is endemic to Vanikoro in the Santa Cruz Islands of Temotu Province in the south-east of the Solomon Islands chain. The species is named for David Gibbs, who discovered it.
The Samoan tropical moist forests are a tropical moist broadleaf forest ecoregion in the Samoan Islands of the Pacific Ocean.
The Peninsular Malaysian montane rain forests is an ecoregion on the Malay Peninsula. It occupies the mountainous spine of the peninsula in Malaysia and southernmost Thailand. It is in the tropical and subtropical moist broadleaf forests biome.
The New Britain–New Ireland montane rain forests is a tropical moist forest ecoregion in Papua New Guinea. The ecoregion includes the mountain rain forests on the islands of New Britain and New Ireland, which lie northeast of New Guinea.
The Fiji tropical moist forests is a tropical moist forest ecoregion in Fiji and Wallis and Futuna. It covers the windward sides of Viti Levu and Vanua Levu, Fiji's largest islands, as well as the smaller Fijian islands and the three islands that make up Wallis and Futuna, an overseas territory of France. The drier leeward sides of Viti Levu and Vanua Levu are home to the distinct Fiji tropical dry forests ecoregion.
The Tongan tropical moist forests is a tropical and subtropical moist broadleaf forests ecoregion that includes the Tonga archipelago and Niue.
The Cook Islands tropical moist forests is a tropical and subtropical moist broadleaf forests ecoregion that covers the Southern Cook Islands in the Cook Islands.
The Tubuai tropical moist forests is a tropical and subtropical moist broadleaf forests ecoregion in French Polynesia. It covers the Austral Islands.
The Society Islands tropical moist forests is a tropical and subtropical moist broadleaf forests ecoregion in the Society Islands of French Polynesia.
The Carolines tropical moist forests is a tropical and subtropical moist broadleaf forests ecoregion in Micronesia. It includes the central and eastern Caroline Islands in the Federated States of Micronesia.
References
1 2 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.
1 2 3 Mueller-Dombois, Dieter, and Francis Raymond Fosberg (1998). Vegetation of the tropical Pacific islands, pp. 84-161. Springer. ISBN 9780387983134, 0387983139
↑ Pillon, Yohan (2018). A new species of Metrosideros (Myrtaceae) from Vanuatu and notes on the genus. Phytotaxa Vol. 347 No. 2: 13 April 2018: 197–200. DOI: https://doi.org/10.11646/phytotaxa.347.2.10
↑ BirdLife International (2020) Endemic Bird Areas factsheet: Vanuatu and Temotu. Downloaded from http://www.birdlife.org on 02/06/2020.
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