Marquesas tropical moist forests

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 French Polynesia, lying north of the Tuamotu islands, south of Hawaii, and approximately west of South America. 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. 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 – , • Hiva Oa – , • Ua Pou – , • Fatu Hiva – , • Ua Huka – , • Eiao – , ==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. ==Flora==

The natural vegetation is principally tropical moist forest, which varies in height and species composition with rainfall and elevation. 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. 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, Vaccinium cereum, Styphelia tameiameiae, and Bidens spp., interspersed with grasses and ferns. 42% of the 320 native vascular plant species are endemic. ==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. Insect genera which have significant radiations of endemic species in the Marquesas include Asymphorodes (Lepidoptera, 21 spp.), Prochaetops (Diptera, 15 spp., possibly not all endemic), Campsicnemus (Diptera, 15 spp.), Pacificola (Coleoptera, 13 spp.), Dichelopa (Lepidoptera, 13 spp.), Sierola (Hymenoptera, 12 spp.), and Campylomma (Hemiptera, 11 spp.). ==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, These agroforestry landscapes provide food, fiber, and building materials while largely preventing soil erosion and nutrient depletion. 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. 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. By the 19th century commercial coconut plantations occupied much of the lowlands. Relatively intact natural vegetation covers about 43% of the ecoregion's area. Most of the lowlands are used for agriculture and pasture, and very little natural lowland forest remains. ==Protected areas==

A 2017 assessment found that 37 km2, or 7%, of the ecoregion is in protected areas. ==References==