São Tomé, Príncipe, and Annobón forests


The São Tomé, Príncipe, and Annobón forests, also known as the São Tomé, Príncipe, and Annobón moist lowland forests, is a tropical moist broadleaf forest ecoregion that covers the islands of São Tomé and Príncipe, which form the island nation of São Tomé and Príncipe, as well as the island of Annobón, which is part of Equatorial Guinea.

Setting

The three islands are volcanic, part of the Cameroon Line of volcanoes that extends from Annobón in the southwest, through the islands of São Tomé, Príncipe, and Bioko, and onto the mainland as Mount Cameroon and the volcanoes of the Cameroon Highlands.
Príncipe is the northernmost island, and lies closest to the African mainland, with an area of 128 km2. São Tomé is the largest of the islands, approximately 836 km2, and lies southwest of Príncipe. Annobón is the southernmost island and lies furthest from the African coast, with an area of 17 km2. The islands are mountainous, with the highest peaks reaching to 2,024 meters on São Tomé, 948 meters on Príncipe, and 598 meters on Annobón.
Príncipe is the oldest of the islands, with the oldest rocks dating back 31 million years. São Tomé is 14 million years old, and Annobón 4.8 million years old. None of the islands have been connected to mainland Africa.
The Tinhosas islands are two unvegetated rocky islets lying 22 km south of Príncipe. Tinhosa Grande has an area of 22 hectares, and reaches 56 meters elevation, and Tinhosa Pequena is 3 hectares in area and 65 meters elevation. See also: Wildlife of São Tomé and Príncipe.

Flora

The natural vegetation of the islands consisted of forests, which varied based on exposure and elevation, including wet lowland forests on the south and southwest portion of the islands, facing the prevailing winds, and drier lowland forests to the north and east in the islands' rain shadow. On São Tomé, lowland forests extend from sea level to 800 meters elevation, montane forests from 800 to 1400 meters elevation, and cloud forests above 1400 meters elevation. The upper montane forests and cloud forests include plants characteristic of afromontane flora, including Olea capensis, Syzygium guineense, and Pauridiantha floribunda, and the endemic trees Afrocarpus mannii, Tabernaemontana stenosiphon, Homalium henriquesii, Croton stelluliferus, Polyscias quintasii, and Craterispermum montanum.
There are 37 endemic plant species on Príncipe, 95 on São Tomé, and 20 on Annobón. Only 16 of the islands' endemic plants are shared by more than one island.

Fauna

Birds

The islands are home to 143 species of birds, including 72 breeding resident species.
28 bird species, all forest dwellers, are endemic to ecoregion. Seven species are endemic to Príncipe. The endemic subspecies of olive ibis on Príncipe, B. o. rothschildi, is probably the rarest bird in the archipelago. Sixteen species are endemic to São Tomé, with two endemic genera. These include the São Tomé ibis, São Tomé olive pigeon, São Tomé scops-owl, São Tomé fiscal, São Tomé shorttail, giant sunbird, São Tomé grosbeak and São Tomé oriole. Annobón is home to the endemic Annobón white-eye and Annobón paradise-flycatcher,. An additional four endemic species inhabit two or more of the islands, including the Príncipe speirops and velvet-mantled drongo, which inhabit both São Tomé and Príncipe, and the São Tomé bronze-naped pigeon which inhabits both São Tomé and Annobón.
The Tinhosas islands are home to the largest seabird colonies in the Gulf of Guinea, with breeding colonies of sooty terns, black noddies, brown noddies, brown boobies
and small numbers of white-tailed tropicbirds.

Mammals

The ecoregion is home to three endemic mammal species: the São Tomé shrew, São Tomé collared fruit bat and São Tomé free-tailed bat.

Protected areas

A 2017 assessment found that 323 km², or 33%, of the ecoregion is in protected areas.
Protected areas in the ecoregion include Obo Natural Park, which includes the Tinhosas islands and portions of São Tomé and Príncipe islands, and the Annobón Natural Reserve on Annobón.