The Southwest Amazon moist forests (NT0166) is an

ecoregion An ecoregion (ecological region) or ecozone (ecological zone) is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of ...

located in the Upper Amazon basin. The forest is characterized by a relatively flat landscape with alluvial plains dissected by undulating hills or high terraces. The biota of the southwest Amazon moist forest is very rich because of these dramatic

edaphic Edaphology (from Greek , ''edaphos'', "ground",, '' -logia'') is concerned with the influence of soils on living beings, particularly plants. It is one of two main divisions of soil science, the other being pedology. Edaphology includes the stu ...

and

topographical Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary sc ...

variations at both the local and regional levels. This ecoregion has the highest number of both mammals and

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...

s recorded for the Amazonian

biogeographic Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...

realm: 257 with 11

endemic species Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

for mammals and 782 and 17 endemics for

s. The inaccessibility of this region, along with few roads, has kept most of the habitat intact. Also, there are a number of protected areas, which preserve this extremely biologically rich ecoregion.

Location

The southwest Amazon moist forest region covers an extensive area of the Upper Amazon Basin comprising four sub-basins: (1) both the Pastaza- Marañon and (2)

Ucayali River The Ucayali River ( es, Río Ucayali, ) is the main headstream of the Amazon River. It rises about north of Lake Titicaca, in the Arequipa region of Peru and becomes the Amazon at the confluence of the Marañón close to Nauta city. The city of ...

sub-basins drain into the Upper Amazon River in Peru; (3) the Acre and (4) Madre de Dios-

Beni is a Japanese R&B singer, who debuted in 2004 under the Avex Trax label. In 2008, Arashiro left Avex Trax and transferred to Universal Music Japan where she started to perform as simply Beni (stylized as BENI). She was initially best known fo ...

sub-basins drain to the east into the Juruá, Purus and

Madeira River The Madeira River ( pt, Rio Madeira, link=no ) is a major waterway in South America. It is estimated to be in length, while the Madeira-Mamoré is estimated near or in length depending on the measuring party and their methods. The Madeira is ...

s; which, in turn, feed into the Amazon River lower down in Brazil. The region is bisected north to south between Peru and Brazil by the small mountain range Serra do Divisor. It extends east to the edge of the Purus Arch, or ancient zone of uplift, in the southwestern area of the Brazilian State of Amazonas. It then extends southeast into northern Bolivia and in a narrow band south along the base of the Andes Mountains. Elevations range from in the west to on the eastern edge of the region. Landforms present in this region include the upland terra firme (non-flooded) mostly on nutrient-poor lateritic soils, ancient alluvial plains (mostly non-flooded) on nutrient-rich soils, and present alluvial plains ( várzea, seasonally flooded) of super-rich sediments renewed with each annual flood. Floristically, distinct lowland humid forest types occur on each of these landforms with the terra firme mature forests and late successional, seasonally flooded forest being the two major types. Permanent swamp forests are common on the alluvial plains. Pockets of nutrient-poor white sand soils are found here that host forests of lower height, a more open

forest canopy In biology, the canopy is the aboveground portion of a plant cropping or crop, formed by the collection of individual plant crowns. In forest ecology, canopy also refers to the upper layer or habitat zone, formed by mature tree crowns an ...

, and lower alpha diversity, but with many endemics. The forests are mostly dense

tropical rain forest Tropical rainforests are rainforests that occur in areas of tropical rainforest climate in which there is no dry season – all months have an average precipitation of at least 60 mm – and may also be referred to as ''lowland equatori ...

, but some patches of open forest exist. The ecoregion contains stretches of

Iquitos várzea The Iquitos várzea (NT0128) is an ecoregion of flooded forest along rivers in Brazil, Peru and Bolivia in the west of the Amazon biome. The forest is seasonally flooded up to by whitewater rivers carrying nutrient-rich sediment from the Andes. ...

along the main rivers, blending into

Purus várzea The Purus várzea (NT0156) is an ecoregion of seasonally flooded várzea forest in the central Amazon basin. It is part of the Amazon biome. The ecoregion is home to a vegetation adapted to floods of up to that may last for eight months. There ...

near the eastern border, where it adjoins the Juruá–Purus moist forests ecoregion. In the southeast, it adjoins the Purus–Madeira moist forests and

Madeira–Tapajós moist forests The Madeira-Tapajós moist forests (NT0135) is an ecoregion in the Amazon basin. It is part of the Amazon biome. The ecoregion extends southwest from the Amazon River between its large Madeira and Tapajós tributaries, and crosses the border into ...

, and in the south merges into the

Beni savanna The Beni savanna, also known as the Llanos de Moxos or Moxos plains, is a tropical savanna ecoregion of the Beni Department of northern Bolivia. Setting The Beni savanna covers an area of in the lowlands of northern Bolivia, with small portion ...

and

Bolivian Yungas The Bolivian Yungas is a tropical and subtropical moist broadleaf forest ecoregion in the Yungas of central Bolivia. Setting The ecoregion occurs in elevations ranging from on the eastern slopes of the Andes in Bolivia, extending into a small p ...

. In the southwest, it adjoins the

Peruvian Yungas The Peruvian Yungas is a tropical and subtropical moist broadleaf forest ecoregion in the Yungas of Peru. Setting The Peruvian Yungas occur on the eastern slopes and valleys of the Peruvian Andes. They form a transition zone between the Southwes ...

. To the west, it adjoins the Ucayali moist forests. In the north it is separated by a band of Iquitos varzea from the Solimões–Japurá moist forests.

General description of flora

Because the ecoregion covers such a vast area, there are climatic, edaphic and floristic differences within it. Generally, the wetter and less seasonal northern forests ( of rain annually) share only 44 percent of the tree species with forests in the slightly drier, more seasonal southern region. This region receives from of rain annually, in different parts. Temperatures over the year range from . At first glance, large areas may appear to be homogeneous dense forests with a canopy high with some emergent trees to towering above the canopy. Structurally, this may be the case; however, the species composition reflects much the opposite: tree species variability reaches upwards to 300 species in a single hectare. There are a few exceptions to this high diversity, mainly where stands dominated by one or several species occur. The first are vast areas (more than ) dominated by the highly competitive arborescent bamboos '' Guadua sarcocarpa'' and '' Guadua weberbaueri'' near Acre, Brazil extending into Peru and Bolivia. Other monodominant stands include swamp forests of the economically important palms ''

Mauritia flexuosa ''Mauritia flexuosa'', known as the moriche palm, ''ité'' palm, ''ita'', ''buriti'', ''muriti'', ''miriti'' (Brazil), ''canangucho'' (Colombia), ''acho'' (Ecuador), or ''aguaje'' (Peru), is a palm tree. It grows in and near swamps and other wet ...

'' and '' Jessenia bataua''. In the north of the region, some of the best known plants yield products of commercial value, such as

rubber Rubber, also called India rubber, latex, Amazonian rubber, ''caucho'', or ''caoutchouc'', as initially produced, consists of polymers of the organic compound isoprene, with minor impurities of other organic compounds. Thailand, Malaysia, an ...

('' Hevea brasiliensis''), mahogany ('' Swietenia macrophylla''), balsam wood (''

Myroxylon balsamum ''Myroxylon balsamum'', Santos mahogany, is a species of tree in the family Fabaceae. It is native to tropical forests from Southern Mexico through the Amazon regions of Peru and Brazil at elevations of . Plants are found growing in well d ...

''),

timber Lumber is wood that has been processed into dimensional lumber, including beams and planks or boards, a stage in the process of wood production. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, w ...

and essential oil ('' Amburana acreana''),

tagua nut ''Phytelephas'' is a genus containing six known species of dioecious Arecaceae, palms (family (biology), family Arecaceae), occurring from southern Panama along the Andes to Ecuador, Bolivia, Colombia, northwestern Brazil, and Peru. They are com ...

('' Phytelephas microcarpa''), and strychnine ('' Strychnos asperula''). An area representative of the southern part of this region, in the north of Bolivia, hosts a seasonal humid high forest to with some emergents reaching in height and many buttressed trunks. The largest trees are ''

Ceiba pentandra ''Ceiba pentandra'' is a tropical tree of the order Malvales and the family Malvaceae (previously emplaced in the family Bombacaceae), native to Mexico, Central America and the Caribbean, northern South America, and (as the variety ''C. pentandr ...

'', ''

Poulsenia armata ''Poulsenia'' is a monotypic genus of trees in the family Moraceae The Moraceae — often called the mulberry family or fig family — are a family of flowering plants comprising about 38 genera and over 1100 species. Most are widespread in tr ...

'', '' Calycophyllum spruceanum'', '' Swietenia macrophylla'', and ''

Dipteryx odorata ''Dipteryx odorata'' (commonly known as "cumaru", "kumaru", or "Brazilian teak") is a species of flowering tree in the pea family, Fabaceae. The tree is native to Central America and northern South America and is semi-deciduous. Its seeds are kn ...

''. Other trees typical in this area are '' Calycophyllum acreanum'', '' Terminalia amazonica'', ''

Combretum laxum ''Combretum'', the bushwillows or combretums, make up the type genus of the family Combretaceae. The genus comprises about 272 species of trees and shrubs, most of which are native to tropical and southern Africa, about 5 to Madagascar, but the ...

'', ''

Mezilaurus itauba ''Mezilaurus itauba'' is a species of tree in the family Lauraceae. It is found in Bolivia, Brazil, Ecuador, French Guiana, Peru, and Suriname Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Surinam ...

'', '' Didymopanax morototoni'', '' Jacaranda copaia'', '' Aspidosperma megalocarpon'', '' Vochisia vismiaefolia'', '' Hirtella lightioides'', and ''

Hura crepitans ''Hura crepitans'', the sandbox tree, also known as possumwood and jabillo, is an evergreen tree of the spurge family (Euphorbiaceae), native to tropical regions of North and South America including the Amazon rainforest. It is also present in p ...

''. Palms include, among others, members of the genera ''

Astrocaryum ''Astrocaryum'' is a genus of about 36 to 40 species of palms native to Central and South America and Trinidad. Description ''Astrocaryum'' is a genus of spiny palms with pinnately compound leaves–rows of leaflets emerge on either side of th ...

'', '' Iriartea'' and '' Sheelea'', '' Oenocarpus mapora'', '' Chelyocarpus chuco'', ''

Phytelephas macrocarpa ''Phytelephas macrocarpa'' is a single-stemmed, unarmed, reclining or erect palm from the extreme northern coastal regions of South America, growing to some 12 m tall. It has been introduced and cultivated in tropical regions all over the world. ...

'', ''

Euterpe precatoria ''Euterpe precatoria'' is a tall, slender-stemmed, pinnate-leaved palm native to Central and South America and Trinidad and Tobago. ''E. precatoria'' is used commercially to produce fruits, although ''Euterpe oleracea'' is more commonly cultivate ...

'', and '' Jessenia bataua''.

Lianas A liana is a long- stemmed, woody vine that is rooted in the soil at ground level and uses trees, as well as other means of vertical support, to climb up to the canopy in search of direct sunlight. The word ''liana'' does not refer to a t ...

are common with about 43 species present. Many Amazonian species reach the southern limit of their distribution here. The Brazil nut tree (''

Bertholletia excelsa The Brazil nut (''Bertholletia excelsa'') is a South American tree in the family Lecythidaceae, and it is also the name of the tree's commercially harvested edible seeds. It is one of the largest and longest-lived trees in the Amazon rainforest. ...

'') is present in the south, but is likely not native this far west in Amazonia.

Biodiversity features

What is distinctive about this region is the diversity of habitats created by edaphic, topographic and climatic variability. Habitat heterogeneity, along with a complex geological and climatic history has led to a high cumulative biotic richness. Endemism and overall richness is high in

vascular plant Vascular plants (), also called tracheophytes () or collectively Tracheophyta (), form a large group of land plants ( accepted known species) that have lignified tissues (the xylem) for conducting water and minerals throughout the plant. They ...

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

s and

vertebrate Vertebrates () comprise all animal taxa within the subphylum Vertebrata () (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with c ...

animals. This is the Amazon Basin's center of diversity for palms. The rare palm '' Itaya amicorum'' is found on the upper

Javari River The Javary River, Javari River or Yavarí River ( es, Río Yavarí, links=no; pt, Rio Javari, links=no) is a tributary of the Amazon that forms the boundary between Brazil and Peru for more than . It is navigable by canoe for from above its ...

. This ecoregion has the highest number of mammals recorded for the Amazonian biogeographic realm: 257 with 11 endemics. Bird richness is also highest here with 782 species and 17 endemics. In the southern part of the Tambopata Reserve, one area that is holds the record for bird species: 554. On the white sand areas in the north, plants endemic to this soil type include '' Jacqueshuberia loretensis'', '' Ambelania occidentalis'', '' Spathelia terminalioides'', and '' Hirtella revillae''. Many widespread Amazonian mammals and reptiles find a home in this region. These include

tapir Tapirs ( ) are large, herbivorous mammals belonging to the family Tapiridae. They are similar in shape to a pig, with a short, prehensile nose trunk. Tapirs inhabit jungle and forest regions of South and Central America, with one species inh ...

s (''

Tapirus terrestris The South American tapir (''Tapirus terrestris''), also commonly called the Brazilian tapir (from the Tupi ''tapi'ira''), the Amazonian tapir, the maned tapir, the lowland tapir, the ''anta'' ( Portuguese), and ''la sachavaca'' (literally "bushc ...

''), jaguars (''

Panthera onca The jaguar (''Panthera onca'') is a large cat species and the only living member of the genus '' Panthera'' native to the Americas. With a body length of up to and a weight of up to , it is the largest cat species in the Americas and the th ...

''), the world's largest living rodents, capybaras (''

Hydrochoerus hydrochaeris The capybaraAlso called capivara (in Brazil), capiguara (in Bolivia), chigüire, chigüiro, or fercho (in Colombia and Venezuela), carpincho (in Argentina, Paraguay and Uruguay) and ronsoco (in Peru). or greater capybara (''Hydrochoerus hydro ...

''),

kinkajou The kinkajou ( /ˈkɪŋkədʒuː/ ''KING-kə-joo''; ''Potos flavus'') is a tropical rainforest mammal of the family Procyonidae related to olingos, coatis, raccoons, and the ringtail and cacomistle. It is the only member of the genus ''Potos'' ...

s ('' Potos flavus''), and white-lipped peccaries (''

Tayassu pecari The white-lipped peccary (''Tayassu pecari'') is a species of peccary found in Central and South America and the only member of the genus ''Tayassu''. Multiple subspecies have been identified. White-lipped peccaries are similar in appearance t ...

''). Some of the globally threatened animals found in this region include black caimans ('' Melanosuchus niger'') and spectacled caimans ('' Caiman crocodilus crocodilus''), woolly monkeys ('' Lagothrix lagotricha''), giant otters ('' Pteronura brasiliensis''), giant anteaters ('' Myrmecophaga tridactyla''), and ocelots ('' Leopardus pardalis''). Pygmy marmosets ('' Cebuella pygmaea''), Goeldi marmosets ('' Callimico goeldii''), pacaranas ('' Dinomys branickii''), and eastern lowland olingos (''

Bassaricyon alleni The eastern lowland olingo (''Bassaricyon alleni'') is a species of olingo from South America, where it is known from the lowlands east of the Andes in Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru and Venezuela.Saguinus fuscicollis'' and '' Saguinus imperator''), brown pale-fronted capuchins (''

Cebus albifrons Gracile capuchin monkeys are capuchin monkeys in the genus ''Cebus''. At one time all capuchin monkeys were included within the genus ''Cebus''. In 2011, Jessica Lynch Alfaro ''et al.'' proposed splitting the genus between the robust capuchin ...

''), squirrel monkeys ('' Saimiri sciureus''), white-faced sakis ('' Pithecia irrorata''), and black spider monkeys ('' Ateles paniscus''). The rare red uakari monkeys (''

Cacajao calvus The bald uakari (''Cacajao calvus'') or bald-headed uakari is a small New World monkey characterized by a very short tail; bright, crimson face; a bald head; and long coat. The bald uakari is restricted to várzea forests and other wooded habitat ...

'') are found in the north in swamp forests. Nocturnal two-toed sloths (''

Choloepus hoffmanni Hoffmann's two-toed sloth (''Choloepus hoffmanni''), also known as the northern two-toed sloth is a species of sloth from Central and South America. It is a solitary, largely nocturnal and arboreal animal, found in mature and secondary rainfor ...

'') are well distributed throughout this region along with the widespread three-toes sloths (''

Bradypus variegatus The brown-throated sloth (''Bradypus variegatus'') is a species of three-toed sloth found in the Neotropical realm of Central and South America. It is the most common of the four species of three-toed sloth, and is found in the forests of Sout ...

''). The Amazon River is a barrier to a number of animals such as the tamarins '' Saguinus nigricollis'', which occur on the north side, and '' Saguinus mystax'', which occurs on the southwest side of the Amazon-Ucayali system. In the region of Manu, 68 species of reptiles and 68 species of amphibians have been reported for the lowland areas while 113 species of amphibians and 118 species of reptiles are reported from Madre de Dios, including the rare and interesting pit-vipers (''

Bothrops bilineatus ''Bothrops bilineatus'', also known as the two-striped forest-pitviper,Campbell JA, Lamar WW. 2004. ''The Venomous Reptiles of the Western Hemisphere''. 2 volumes. Comstock Publishing Associates, Ithaca and London. 870 pp. 1500 plates. . parrots ...

'', '' Bothrops brazili''), and frogs such as '' Dendrophidion sp.'', '' Rhadinaea occipitalis'', and '' Xenopholis scalaris''.

Current status

Much of the natural habitat of the region remains intact, protected by sheer inaccessibility. People have dwelled along the major rivers for millennia and have subtly altered the forests on a small scale, but around the urban centers development proceeds. Very few roads exist in the region, limiting development. Intense

deforestation Deforestation or forest clearance is the removal of a forest or stand of trees from land that is then converted to non-forest use. Deforestation can involve conversion of forest land to farms, ranches, or urban use. The most concentrated ...

is constrained to the few roads that do exist or around urban centers such as Iquitos,

Puerto Maldonado Puerto Maldonado () is a city in southeastern Peru in the Amazon rainforest west of the Bolivian border, located at the confluence of the Tambopata and Madre de Dios rivers. The latter river joins the Madeira River as a tributary of the Amazon ...

, and Rio Branco.

Manú National Park Manú National Park ( es, Parque Nacional del Manú) is a national park and biosphere reserve located in the regions of Madre de Dios and Cusco in Peru. It protects a diverse number of ecosystems including lowland rainforests, cloud forests and ...

, a

World Heritage Site A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...

, protects of pristine lowland forest in southern Peru, a large part of which falls into this ecoregion. The nearby

Tambopata-Candamo Tambopata National Reserve ( es, Reserva Nacional Tambopata) is a Peruvian nature reserve located in the southeastern region of Madre de Dios. It was established on September 4, 2000, by decree of President Alberto Fujimori. The reserve protects se ...

reserve protects seven major forest types. This reserve offers refuge to game species that have been over-hunted in other areas such as tapirs,

spider monkey Spider monkeys are New World monkeys belonging to the genus ''Ateles'', part of the subfamily Atelinae, family Atelidae. Like other atelines, they are found in tropical forests of Central and South America, from southern Mexico to Brazil. The ...

s, jaguars, capybaras, white-lipped peccaries, monkeys,

caimans A caiman (also cayman as a variant spelling) is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family, the other being alligators. Caimans inhabit Mexico, Central and South America fr ...

and

river turtle The hickatee (''Dermatemys mawii'') or in Spanish ''tortuga blanca'' ('white turtle'), also called the Central American river turtle, is the only living species in the family Dermatemydidae. The species is found in the Atlantic drainages of Cen ...

s. The

Manuripi-Heath Amazonian Wildlife National Reserve Manuripi-Heath Amazonian Wildlife National Reserve (''Reserva Nacional de Vida Silvestre Amazónica Manuripi-Heath'') is a protected area in the Pando Department, Bolivia, situated in the Manuripi Province Manuripi is one of the five provinces ...

is located in the southernmost area of this region in Bolivia covering of dense tropical forest. Several extractive reserves, the largest being

Chico Mendes Extractive Reserve Chico Mendes Extractive Reserve ( pt, Reserva Extrativista Chico Mendes) is an extractive reserve in the state of Acre, Brazil. Location The Chico Mendes Extractive Reserve has an area of . It is in the Amazon biome. The reserve covers parts o ...

and Alto Juruá Extractive Reserve, are actively managed in Brazil. Other protected areas include national parks (

Serra do Divisor National Park The Serra do Divisor National Park ( pt, Parque Nacional da Serra do Divisor) is a national park on the westernmost point of Brazil, in the state of Acre, near the Peruvian border. It also has the highest point in that state, reaching 609 meters ...

Madidi National Park Madidi () is a national park in the upper Amazon Basin, Amazon river basin in Bolivia. Established in 1995, it has an area of 18,958km². Along with the nearby protected (though not necessarily contiguous) areas Manuripi-Heath, Apolobamba, and th ...

, Isoboro Secure National Park, Bahuaja-Sonene National Park), national forests,

Rio Acre Ecological Station Rio Acre Ecological Station ( pt, Estação Ecológica do Rio Acre) is an ecological station in the state of Acre, Brazil. Location The Rio Acre Ecological Station, which covers , was created on 2 June 1981. It is administered by the Chico Mende ...

, Antimari State Forest, Apurimac Reserve Zone, among others. Most protected areas suffer from insufficient administration and patrol.

Types and severity of threats

Hunting may be threatening populations of the tapir (''

'') and large primates in the north. Some habitat is threatened by expansion of the agricultural and pastoral frontier,

gold mining Gold mining is the extraction of gold resources by mining. Historically, mining gold from alluvial deposits used manual separation processes, such as gold panning. However, with the expansion of gold mining to ores that are not on the surface, ...

, and selective logging that erodes the genetic diversity of a few valuable timber species. The economically important palm ''

'' is being depleted in some areas by unsustainable palm heart extraction. A dramatic problem that exists in the Brazilian State of Acre and in the adjacent area of Peru is the spread of the invasive '' Guadua'' bamboo forests. This highly competitive bamboo invades and dominates abandoned clearings and threatens to dominate the disturbed areas in this region. Logging along major rivers and near urban centers has decimated populations of mahogany ('' Swietenia macrophylla''), tropical cedar ('' Cedrela odorata''), and kapok (''

''). During the period from 2004 to 2011 the ecoregion experienced an annual rate of habitat loss of 0.17%.

References

Sources

* *

Location

General description of flora

Biodiversity features

Current status

Types and severity of threats

References

Sources

Further reading