Tongan tropical moist forests
Tongan tropical moist forests | |
---|---|
Ecology | |
Realm | Oceanian |
Biome | tropical and subtropical moist broadleaf forests |
Geography | |
Area | 549 km2 (212 sq mi) |
Countries | |
Conservation | |
Conservation status | Critical/endangered[1] |
Global 200 | South Pacific Islands forests |
Protected | 117 km² (21%)[2] |
The Tongan tropical moist forests is a tropical and subtropical moist broadleaf forests ecoregion that includes the Tonga archipelago and Niue.
Geography
The ecoregion includes the Tonga archipelago, a group of 170 islands that extends 800 km north to south between 15º to 23ºS latitude and 173º to 177º W longitude, and comprise the nation of Tonga. It also includes Niue, which lies 400 km east of Tonga at 19º S latitude and 169º W longitude.[1]
The Tonga archipelago lies at the boundary of the
Niue is an uplifted coral atoll, with cliffs along the shoreline and without a fringing coral reef. It covers an area of 259 km2.[1]
The islands have been inhabited for about 3000 years.
Climate
The ecoregion has a humid tropical climate. Mean daily temperatures generally range from 24º to 30 °C in February, the warmest month, to 20º to 26 °C in August, the coolest month. Average annual rainfall is 2000 mm or more, and higher on windward slopes and at higher elevations. Rainfall is generally higher between December and April. Leeward lowlands can experience seasonal droughts between May and November.[1]
Flora
The natural vegetation is moist broadleaf forest.
Tropical lowland rain forests predominate below 500 meters elevation. Evergreen trees form a continuous canopy up to 30 meters in height. Common canopy trees include
On coastal dunes and relatively recent lava and ash deposits where soils are thinner and drier, forests of Casuarina equisetifolia predominate, with low trees and shrubs including Pandanus tectorius, Syzygium dealbatum, Hibiscus tiliaceus, and Scaevola taccada.[1]
Littoral forests of Hernandia nymphaeifolia, Barringtonia asiatica, and Casuarina equisetifolia grow closest to the coast in areas with salt spray. Immediately inland are coastal forests with Pisonia grandis and Excoecaria agallocha as the predominant trees.[4]
Mangrove scrub and mangrove forest are found in saltwater wetlands on coral atolls and around the shores of the larger islands' coastal lagoons.[1] Mangrove scrub is found on estuaries and reef flats and on the edges of mangrove forests. The small- to medium-sized trees Rhizophora mangle, Rhizophora stylosa, and Lumnitzera littorea are dominant. Where conditions are favorable mangrove forests dominated by Bruguiera gymnorhiza with Xylocarpus moluccensis and X. granatum replace the mangrove scrub.[3]
Montane forests are found above 500 metres elevation on the island of
There are 419 native species of vascular plants in the Tonga, and approximately 3% are endemic.[1]
Plants endemic to Tonga include Alphitonia franguloides var. obtusa, Arytera bifoliata, Grewia amicorum, Grewia populoides, Guioa lentiscifolia, Meiogyne amicorum, Oldenlandia debilis, Pandanus amicalis, Pandanus tongatapuensis, Pandanus vavauensis, Phyllanthus amicorum, Pittosporum yunckeri, Psychotria euaensis, Scaevola porrecta, and Xylosma smithiana.[5]
Several species are endemic to one or two islands:[5]
- Phyllostegia tongaensis is endemic to 'Ata
- Aglaia heterotricha, Didymocheton tongensis, Hedycarya alternifolia, Ixora yunckeri, Plantago euana, and the fern Thelypteris macroptera are endemic to 'Eua
- Dennstaedtia parksii and the orchid Robiquetia tongaensis are endemic to 'Eua and Tongatapu
- the conifer Podocarpus pallidus is endemic to 'Eua and Vava'u
- Psychotria kaoensis and Selaginella yunckeri are endemic to Kao
- Atractocarpus crosbyi, Casearia buelowii, and the palm Pritchardia pacifica are endemic to Vava'u.
Peperomia pallida var. niueana, Myoporum nieuanum, and the orchid Dendrobium niueense are endemic to Niue.[6]
Fauna
There are no native land mammals in the ecoregion. Native bats include the
Tonga has native 20 species of land and freshwater birds. The
The islands are home to numerous seabirds, including brown noddy (Anous stolidus), Phoenix petrel (Pterodroma alba), and bristle-thighed curlew (Numenius tahitiensis). Seabird breeding colonies are mostly limited to offshore islets free of rats, which prey on eggs and chicks.[1]
Niue has 12 native species of land birds and six species of seabirds, including two endemic subspecies.[1]
There are 20 known species of
Protected areas
A 2017 assessment found that 117 km2, or 21%, of the ecoregion is in protected areas.[2]
References
- ^ a b c d e f g h i j k l m n o p "Tongan tropical moist forests". Terrestrial Ecoregions. World Wildlife Fund.
- ^ PMID 28608869.) Supplemental material 2 table S1b.
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: CS1 maint: date and year (link - ^ a b c Whistler, W. Arthur (1992). "Vegetation of Samoa and Tonga". Pacific Science (1992), vol. 46, no. 2: 159-178
- ^ a b Franklin, J., Wiser, S. K., Drake, D. R., Burrows, L. E., & Sykes, W. R. (2006). Environment, Disturbance History and Rain Forest Composition across the Islands of Tonga, Western Polynesia. Journal of Vegetation Science, 17(2), 233–244. http://www.jstor.org/stable/4499169
- ^ a b Endemic plants of Tonga, from the World Checklist of Vascular Plants (WCVP) checklist builder. Accessed 10 December 2023. https://checklistbuilder.science.kew.org/reportbuilder.do
- ^ Endemic plants of Niue, from the World Checklist of Vascular Plants (WCVP) checklist builder. Accessed 10 December 2023. https://checklistbuilder.science.kew.org/reportbuilder.do