Marquesas tropical moist forests
Marquesas tropical moist forests | |
---|---|
Ecology | |
Realm | Oceanian |
Biome | tropical and subtropical moist broadleaf forests |
Geography | |
Area | 540 km2 (210 sq mi) |
Country | French Polynesia |
Administrative subdivisions | Marquesas Islands |
Conservation | |
Conservation status | Critical/endangered[1] |
Protected | 37 km2 (7%)[2] |
The Marquesas tropical moist forests is a tropical and subtropical moist broadleaf forests ecoregion in the Marquesas Islands of French Polynesia.
Geography
The Marquesas Islands include 12 major islands of volcanic origin. They extend northwest to southeast between 8º and 11º S latitude and 139º and 141º W longitude. The islands are part of
The islands are volcanic in origin, created by the slow west-northwest movement of the Pacific Plate over the Marquesas hotspot. The northwestern islands are approximately 6 million years old, and the southeast islands are younger at 1.3 million years old.[1]
The islands are composed of basalt rock, and have mountainous terrain with sharp ridges, deep canyons, and steep cliffs. The largest and highest islands are:
- Nuku Hiva – 339 km2 (131 sq mi), 1,224 m (4,016 ft)
- Hiva Oa – 316 km2 (122 sq mi), 1,213 m (3,980 ft)
- Ua Pou – 105.6 km2 (40.8 sq mi), 1,230 m (4,040 ft)
- Fatu Hiva– 85 km2 (33 sq mi), 1,125 m (3,691 ft)
- Ua Huka – 83.4 km2 (32.2 sq mi), 857 m (2,812 ft)
- Eiao – 43.8 km2 (16.9 sq mi), 576 m (1,890 ft)
Climate
The islands have a tropical climate. Average annual rainfall varies with elevation and orientation, from 500 mm on leeward lowlands to 4000 mm or more on windward slopes above 1000 meters on the five highest islands. Trade winds blow from the southeast during most of the year, and the windward eastern slopes tend to be wetter than the leeward western slopes. The east-facing mountain slopes are cooler, with mean temperatures of 15º to 25 °C, while the hottest mean temperatures (25º to 29 °C) are in the dry western lowlands.[1]
Flora
The natural vegetation is principally tropical moist forest, which varies in height and
Lowland forests extend up to about 300 m with areas of up to 2000 mm of annual rainfall. Typical lowland forests are dominated by Pisonia grandis, which forms a canopy up to 15 meters high, along with the trees Thespesia populnea, Calophyllum inophyllum, and Terminalia glabrata. Tropical dry forest occurred on drier leeward slopes of the larger islands, characterized by species of Hibiscus, Pandanus, Thespesia, and Cordia.[1] Native lowland forests have mostly been replaced with introduced trees. Archeological evidence shows that some pre-settlement lowland forest trees are now extinct, including species of Planchonella and cf. Sideroxylon (Sapotaceae), and a species of Allophylus (Sapindaceae) extirpated from Nuku Hiva.[3]
Mid-elevation forests occur between 300 and 800 meters elevation, with annual rainfall of 2,000 to 3,000 mm. Typical trees include Hibiscus tiliaceus, Pandanus tectorius, Alphitonia marquesensis, and Pterophylla marquesana, which form a canopy up to 20 meters high. Understory plants include Angiopteris evecta and Cyclophyllum barbatum. From 800 to 1000 meters elevation, Hernandia nukuhivensis, and the tree ferns Cyathea affinis and Sphaeropteris feani predominate in wet areas, and Metrosideros collina and Pterophylla marquesana on drier slopes. A cloud forest belt occurs above 1000 meters elevation, with a low-canopied forest of Cheirodendron bastardianum, Ilex anomala, and Metrosideros collina, with climbers of Freycinetia spp.[1]
Mountaintops above 1,200 m are drier and windswept, supporting a heathland of low trees and shrubs up to one meter high, including M. collina,
42% of the 320 native vascular plant species are endemic.[1]
Fauna
The ancestors of the Marquesas' native fauna arrived via long-distance dispersal from other islands, and evolved into distinct forms over millions of years.[1]
The ecoregion has 19 breeding seabird species and 11 resident land birds, including ten endemic bird species. Endemic species include the
The Marquesas are home to at least 78 species of land and freshwater snails.[1]
There are 1198 species of terrestrial
Human impacts
Humans have altered landscape and flora and fauna of the islands since the arrival of Polynesians in the 11th and 12th centuries. Polynesian settlers introduced 33 to 37 species of plants to the islands,
Europeans started visiting the islands in the 18th century and later conquered and settled there. Europeans brought with them many more exotic plants and animals, including black rats (Rattus rattus) which have decimated the islands' birds.[1] Introduced sheep and goats have denuded some areas of vegetation, particularly in drier parts of the islands. Introduced grasses, shrubs, and trees are often fast-growing and adapted to grazing and fire, and can outcompete native species.[4] By the 19th century commercial coconut plantations occupied much of the lowlands.[7]
Relatively intact natural vegetation covers about 43% of the ecoregion's area.[2] Most of the lowlands are used for agriculture and pasture, and very little natural lowland forest remains.[1]
Protected areas
A 2017 assessment found that 37 km2, or 7%, of the ecoregion is in protected areas.[2]
References
- ^ a b c d e f g h i j k l m n o "Marquesas 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 - ^ Jennifer M. Huebert, Melinda S. Allen (2016) Six centuries of anthropogenic forest change on a Polynesian high island: Archaeological charcoal records from the Marquesas Islands. Quaternary Science Reviews, Volume 137, 2016, Pages 79-96. ISSN 0277-3791, https://doi.org/10.1016/j.quascirev.2016.01.017.
- ^ a b c Allen MS, Lewis T, Porch N. Lost bioscapes: Floristic and arthropod diversity coincident with 12th century Polynesian settlement, Nuku Hiva, Marquesas Islands. PLoS One. 2022 Mar 30;17(3):e0265224. doi: 10.1371/journal.pone.0265224. PMID 35353828; PMCID: PMC8967401.
- ^ Hembry, DH. Evolutionary biogeography of the terrestrial biota of the Marquesas Islands, one of the world's remotest archipelagos. Journal of Biogeography. 2018; 45: 1713–1726. https://doi.org/10.1111/jbi.13378
- ^ a b Jennifer M. Huebert, Melinda S. Allen (2020) Anthropogenic forests, arboriculture, and niche construction in the Marquesas Islands (Polynesia). Journal of Anthropological Archaeology Volume 57, 2020, 101122, ISSN 0278-4165, https://doi.org/10.1016/j.jaa.2019.101122.
- ^ a b Quintus, S., Huebert, J., Kirch, P. V., Lincoln, N. K., & Maxwell, J. (2019). Qualities and Contributions of Agroforestry Practices and Novel Forests in Pre-European Polynesia and the Polynesian Outliers. Human Ecology, 47(6), 811–825. http://www.jstor.org/stable/45281844
External links
- "Marquesas tropical moist forests". Terrestrial Ecoregions. World Wildlife Fund.
- Marquesas tropical moist forests (DOPA)
- Marquesas tropical moist forests (Encyclopedia of Earth)