Solomon Islands rainforests

• Category: Forest Biomes.
• Geographic Location: Pacific Ocean.

Summary: The Solomon Islands rainforests, although home to a limited number of species of mammals, birds, and amphibians, have an unusually large proportion of endemic species.

The Solomon Islands is a sovereign state consisting of more than one thousand islands located in the Pacific Ocean, east of Papua New Guinea. Most of the Solomon Islands are part of the Solomon Islands Rain Forest ecoregion. Because of the isolation of this island chain and the rugged topography and the lushness of the habitats here, a full range of endemic (found nowhere else) species of flora and fauna live in these tropical rainforests.

The oceanic-equatorial climate here provides a mean temperature of 80.6 degrees F (27 degrees C) to 89.6 degrees F (32 degrees C). While most of the Solomon Islands are within the Solomon Islands Rainforest biome, the Santa Cruz Islands group makes up part of the somewhat different Vanuatu Rainforest ecosystem.

Soil quality in the Solomon Islands rainforest varies greatly, from rich volcanic soil to infertile limestone. The climate here is considered tropical wet; the ecosystem is comprised chiefly of tropical lowland and montane forest habitats. Although most land on the islands lies below an elevation of 3,000 feet (914 meters), the predominant terrain type is forested hills.

Flora

Seven broad vegetation groups exist in the Solomon Islands, including coastal strand vegetation, freshwater swamp forests, mangrove forests, montane rainforest, two types of lowland rainforests, seasonally dry forest, and grasslands. This latter type is found only on the large island of Guadalcanal. The lowland rainforest is the most common plant community.

The lowland rainforest canopy tends to be uneven, as frequent natural disturbances such as subsidence, fallen trees, and tropical storms disrupt it. Six diverse lowland rain forest types are spread about the Solomon Islands, resulting from a forest’s location on the northern or western side of an island, its elevation, and the local level of disturbance.

A variety of common tree species exist here; among the most common are penaga (Calophyllum kajewskii), kamani (C. vitiense), the fruit-bearing sumac (Campnosperma brevipetiolata), sea bean (Maranthes corymbosa), beabea (Schizomeria serrata), elephant apple (Dillenia salomonensis), the deciduous whitewood (Endospermum medullosum), and the eucalypt black wattle (Gmelina mollucana). Other important plants include the many endemic orchid and palm species. 

Fauna

As true oceanic islands, the Solomon Islands are home to a high number of endemic vertebrates. The rainforests have fewer mammals than other nearby regions, such as New Guinea to the west, but there is a large gallery of bats here. The Solomon Islands rainforests are thought to contain fewer than fifty mammal species. At least half of these are endemic to the biome, including nine rodent species; fifteen species of the family Pteropodidae, or old-world fruit-eating bats; a free-tailed bat of genus Molossus; and the Solomons horseshoe bat (Anthops ornatus). In 2017, scientists described the Vangunu giant rat (Uromys vika), an endemic arboreal rodent from Vangunu Island.

A similar pattern holds with avian species: relatively low diversity but a high rate of endemism. The Solomon Islands rainforests are a haven to more than forty families and subfamilies of birds, with perhaps two hundred species. More than one-third of these are endemic to this ecosystem, a factor making the Solomon Islands rainforests a critical global area for bird conservation.

Among the endangered rainforest bird species found here are Woodford’s rail (Hypotaenidia woodfordi), Makira moorhen (Pareudiastes silvestris), chestnut-bellied imperial pigeon (Ducula brenchleyi), white-eyed starling (Aplonis brunneicapillus), and imitator sparrowhawk (Accipiter imitator).

Environmental Threats

Direct human alteration of riverine and coastal areas, along with typically poor soils in some areas, has contributed to the depletion of lowland Solomon Island rainforests and fragmentation of remnant coastal swamp vegetation and pandanus thickets. Some of the outlying coral atolls of the archipelago are in better native condition than the larger islands. While timber is the nation’s most significant export, illegal logging strips the land of trees, carves logging roads through sensitive habitats, and allows the rains to wash away the mountain soil. Such devastation has negative effects on communities as well when they lose their natural resources. Corruption of local and national authorities makes stopping such operations nearly impossible. Protected areas relevant to rainforest conservation include the East Rennell World Heritage Site on Rennell Island and the Kolombangara Forest Reserve.

The rainforests are subject to tropical cyclones from November to April; these storms have proved to be sources of natural disturbance to flora and fauna, as have extreme droughts, which occur with some regularity, generally on a six- to twenty-year cycle. However, climate change impacts upon this region, already prone to major storms and droughts, could push some habitats here beyond tipping points that have evolved over thousands of years.

Bibliography

Beck, John. “Logging Is Corrupting These Islands. One Village Fights Back—and Wins.” National Geographic, 3 Jan. 2020, www.nationalgeographic.com/science/article/deforestation-in-the-solomon-islands. Accessed 11 Mar. 2026.

Bennett, Judith. Pacific Forest: A History of Resource Control and Contest in Solomon Islands, c. 1800-1997. Brill, 2021.

“Climate and Monthly Weather Forecast Solomon Islands.” Weather Atlas, 24 May 2024, www.weather-atlas.com/en/solomon-islands-climate. Accessed 11 Mar. 2026.

“East Rennell.” UNESCO World Heritage Convention, whc.unesco.org/en/list/854. Accessed 11 Mar. 2026.

Gillespie, A., and W. C. G. Burns, editors. Climate Change in the South Pacific: Impacts and Responses in Australia, New Zealand, and Small Island States, vol. 2, Kluwer Academic Publishers, 2000.

“Kolombangara Forest Reserve.” Protected Planet, www.protectedplanet.net/4362. Accessed 11 Mar. 2026.

Lavery, Tyrone H., and Hikuna Judge. “A New Species of Giant Rat (Muridae, Uromys) from Vangunu, Solomon Islands.” Journal of Mammalogy, vol. 98, no. 6, 1 Dec. 2017, pp. 1518–30, doi:10.1093/jmammal/gyx116. Accessed 11 Mar. 2026.

McKibben, B. Deep Economy: Economics as if the World Mattered. Oneworld Publications, 2007.

Wolff, T. “The Fauna of Rennell and Bellona, Solomon Islands.” Philosophical Transactions of the Royal Society of London, Series B, Biological Sciences, vol. 255, no. 800, 1969, pp. 321–43, doi:10.1098/rstb.1969.0014. Accessed 12 Mar. 2026.