Napo moist forests

The Napo moist forests ecoregion covers part of the Amazon basin to the east of the Andes in the north of Peru, the east of Ecuador and the south of Colombia. It has an area of 25,174,684 hectares (62,208,000 acres).[1] The ecoregion extends from the foothills of the Andes in the west almost to the city of Iquitos, Peru in the east, where the Napo and Solimões (Upper Amazon) rivers join.[2]

In the extreme northwest the Napo moist forests ecoregion transitions into Cordillera Oriental montane forests to the west. Otherwise it transitions into Eastern Cordillera Real montane forests in the west. To the south it transitions into Ucayali moist forests, and into a broad belt of Iquitos várzea along the Marañón / Solimões river. To the east it transitions into Solimões-Japurá moist forests in the south and Caquetá moist forests in the north. The Napo moist forests contain areas of Iquitos várzea along rivers in the south and areas of Purus várzea along rivers in the north..[3]

The terrain consists of floodplains and very low hills.[1] To the west it is bounded by the foothills of the Andes. It slopes gently down from elevations of 300–400 metres (980–1,310 ft) in the west to elevations of 100 metres (330 ft) in the east. In the plains of the north the higher land rises no more than 10 metres (33 ft) above river level. Soils include older material from the Guiana Shield mixed with Quaternary sediments washed down from the Andes.[2]

The Marañón River defines the southern boundary of the ecoregion. The Caguán River, a tributary of the Caquetá River defines the eastern boundary in Colombia. The Napo River, a tributary of the Solimões, defines the eastern boundary in Peru. Other important Amazon basin rivers that cross the ecoregion include the Morona, Pastaza, Tigre and Curaray, and the headwaters of the Caquetá and Putumayo.[2]

The ecoregion has a humid tropical climate. Mean annual temperatures are 26 °C (79 °F). At different times of year, different elevations and different distances from the equator monthly temperatures may vary from 12 to 38 °C (54 to 100 °F). Annual rainfall in the furthest west of the ecoregion is up to 4,000 millimetres (160 in), while in the east it is 2,500–3,000 millimetres (98–118 in), still a very high level. There is a "dry" season with rather less rain than at other times of the year.[2] At a sample location at 1.75°S 75.75°W / -1.75; -75.75 the Köppen climate classification is "Af": equatorial, fully humid.[4] At this location monthly mean temperatures range from 25 °C (77 °F) in July to 26.9 °C (80.4 °F) in November. Yearly total rainfall is about 3,250 millimetres (128 in) Monthly rainfall varies from 193.7 millimetres (7.63 in) in December to 366.9 millimetres (14.44 in) in May.[4]

In a 1 hectare (2.5 acres) area of the Napo moist forests over 310 species of trees have been counted.[5] The Yasuní Biosphere Reserve contains about 4,000 species of plants.[6] 138 species of orchid have been reported below 300 metres (980 ft) of elevation in Ecuador.[2]

white-banded swallow (Atticora fasciata) on the Tiputini River in Yasuni National Park

common squirrel monkey (Saimiri sciureus) in the Cuyabeno Wildlife Reserve

The Yasuní Biosphere Reserve has at least 70 species of mammals. This includes 13 primate species including the silvery woolly monkey (Lagothrix poeppigii), Venezuelan red howler (Alouatta seniculus), white-bellied spider monkey (Ateles belzebuth) and monk saki (Pithecia monachus). Other mammals include the South American tapir (Tapirus terrestris), white-lipped peccary (Tayassu pecari), jaguar (Panthera onca), Amazon river dolphin (Inia geoffrensis), tucuxi (Sotalia fluviatilis) and giant otter (Pteronura brasiliensis).[6] The region is home to the spectral bat (Vampyrum spectrum), the largest bat in the New World.[5] Endangered mammals include white-bellied spider monkey (Ateles belzebuth), giant otter (Pteronura brasiliensis) and mountain tapir (Tapirus pinchaque).[7]

The Yasuní Biosphere Reserve has more than 400 fish species.[6] Endangered amphibians include Hemiphractus johnsoni (Johnson's horned treefrog), Hyloxalus cevallosi (Palanda rocket frog) and Pristimantis festae.[7]

The Yasuní Biosphere Reserve has more than 500 species of birds.[6] Endangered birds include wattled curassow (Crax globulosa).[7]