[1] The islands are composed of basalt rock, and have mountainous terrain with sharp ridges, deep canyons, and steep cliffs.

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.

Typical trees include Hibiscus tiliaceus, Pandanus tectorius, Alphitonia marquesensis, and Pterophylla marquesana, which form a canopy up to 20 meters high.

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.

[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, Vaccinium cereum, Styphelia tameiameiae, and Bidens spp., interspersed with grasses and ferns.

[1] 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] There are 1198 species of terrestrial arthropods in the Marquesas, 681 (53%) of which are considered endemic to the islands, 138 (11.5%) are introduced, and the remainder mostly native with some of uncertain status.

The majority of the endemic insect species are contained in five orders: Coleoptera (beetles), Diptera (flies), Hemiptera (true bugs), Hymenoptera (wasps, bees and ants), and Lepidoptera (butterflies and moths).

[6][1] Much of the native lowland forest vegetation was replaced with traditional agroforestry systems centered on the introduced breadfruit and coconut.

[7] These agroforestry landscapes provide food, fiber, and building materials while largely preventing soil erosion and nutrient depletion.