Southwest Amazon Moist Forests
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The Southwest Amazon moist forests (NT0166) is an
ecoregion An ecoregion (ecological region) is an ecological and geographic area that exists on multiple different levels, defined by type, quality, and quantity of environmental resources. Ecoregions cover relatively large areas of land or water, and c ...
located in the Upper
Amazon basin The Amazon basin is the part of South America drained by the Amazon River and its tributary, tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries ...
. The forest is characterized by a relatively flat landscape with
alluvial plain An alluvial plain is a plain (an essentially flat landform) created by the deposition of sediment over a long period by one or more rivers coming from highland regions, from which alluvial soil forms. A ''floodplain'' is part of the process, bei ...
s dissected by undulating hills or high terraces. The biota of the southwest Amazon moist forest is very rich because of these dramatic edaphic and
topographical Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the landforms and features themselves, or a description or depiction in maps. Topography is a field of geoscience and planetary scienc ...
variations at both the local and regional levels. This ecoregion has the highest number of both
mammal A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
s and
bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
s recorded for the Amazonian biogeographic realm: 257 with 11
endemic species Endemism is the state of a species being found only 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 foun ...
for mammals and 782 and 17 endemics for
bird Birds are a group of warm-blooded vertebrates constituting the class (biology), class Aves (), characterised by feathers, toothless beaked jaws, the Oviparity, laying of Eggshell, hard-shelled eggs, a high Metabolism, metabolic rate, a fou ...
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 (, ) 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 river, Marañón close to Nauta city. The city of ...
sub-basins drain into the Upper Amazon River in Peru; (3) the
Acre The acre ( ) is a Unit of measurement, unit of land area used in the Imperial units, British imperial and the United States customary units#Area, United States customary systems. It is traditionally defined as the area of one Chain (unit), ch ...
and (4) Madre de Dios- Beni sub-basins drain to the east into the Juruá, Purus and
Madeira River The Madeira River ( ) 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 the biggest tributary of ...
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 The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long and wide (widest between 18°S ...
. 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 plain An alluvial plain is a plain (an essentially flat landform) created by the deposition of sediment over a long period by one or more rivers coming from highland regions, from which alluvial soil forms. A ''floodplain'' is part of the process, bei ...
s (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 A swamp is a forested wetland.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p. Swamps are considered to be transition zones because both land and water play a role in ...
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, the canopy is the upper layer or habitat zone, formed by mature tree crowns and includ ...
, and lower alpha diversity, but with many endemics. The forests are mostly dense tropical rain forest, but some patches of open forest exist. The ecoregion contains stretches of Iquitos várzea along the main rivers, blending into Purus várzea near the eastern border, where it adjoins the
Juruá–Purus moist forests The Juruá–Purus moist forests (NT0133) is an ecoregion in northwest Brazil in the Amazon biome. The terrain is very flat and soils are poor. The rivers flood annually. There are no roads in the region, and the dense rainforest is relatively int ...
ecoregion. In the southeast, it adjoins the Purus–Madeira moist forests and Madeira–Tapajós moist forests, and in the south merges into the
Beni savanna The Llanos de Moxos, also known as the Beni savanna or Moxos plains, is a tropical and subtropical grasslands, savannas, and shrublands, tropical savanna ecoregion of the Beni Department of northern Bolivia. Setting The Llanos de Moxos covers a ...
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 ...
. In the southwest, it adjoins the
Peruvian Yungas The Peruvian Yungas comprise a tropical and subtropical moist broadleaf forest ecoregion in Peru. History During the Inca Empire, the term ''yunga'' referred to both the western and eastern slopes of the Andes and their inhabitants. In the Span ...
. 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 Relative species abundance is a component of biodiversity and is a measure of how common or rare a species is relative to other species in a defined location or community.Hubbell, S. P. 2001. ''The unified neutral theory of biodiversity and biogeog ...
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), ''morete or acho'' (Ecuador), ''palma real'' (Bolivia), or ''aguaje'' (Peru), is a Arecaceae, palm t ...
'' 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. Types of polyisoprene ...
('' Hevea brasiliensis''),
mahogany Mahogany is a straight- grained, reddish-brown timber of three tropical hardwood species of the genus ''Swietenia'', indigenous to the AmericasBridgewater, Samuel (2012). ''A Natural History of Belize: Inside the Maya Forest''. Austin: Universit ...
('' Swietenia macrophylla''), balsam wood ('' Myroxylon balsamum''),
timber Lumber is wood that has been processed into uniform and useful sizes (dimensional lumber), including beams and planks or boards. Lumber is mainly used for construction framing, as well as finishing (floors, wall panels, window frames). ...
and
essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the ...
('' Amburana acreana''), tagua nut ('' Phytelephas microcarpa''), and
strychnine Strychnine (, , American English, US chiefly ) is a highly toxicity, toxic, colorless, bitter, crystalline alkaloid used as a pesticide, particularly for killing small vertebrates such as birds and rodents. Strychnine, when inhaled, swallowed, ...
('' 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 (biology), order Malvales and the family (biology), family Malvaceae (previously emplaced in the family Bombacaceae), native to Mexico, Central America and the Caribbean, northern South America, ...
'', '' Poulsenia armata'', '' 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 Northern South America and is semi-deciduous. Its seed In botany, a seed ...
''. Other trees typical in this area are '' Calycophyllum acreanum'', '' Terminalia amazonica'', '' Combretum laxum'', '' Mezilaurus itauba'', '' Didymopanax morototoni'', '' Jacaranda copaia'', '' Aspidosperma megalocarpon'', '' Vochisia vismiaefolia'', '' Hirtella lightioides'', and '' Hura crepitans''. Palms include, among others, members of the
genera Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...
'' Astrocaryum'', '' Iriartea'' and '' Sheelea'', '' Oenocarpus mapora'', '' Chelyocarpus chuco'', '' Phytelephas macrocarpa'', '' Euterpe precatoria'', and '' Jessenia bataua''. Lianas are common with about 43 species present. Many Amazonian species reach the southern limit of their distribution here. The Brazil nut tree ('' Bertholletia excelsa'') 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 (; ), are plants that have lignin, lignified tissues (the xylem) for conducting water and minerals throughout the plant. They also have a specialized non-lignified Ti ...
s,
invertebrate Invertebrates are animals that neither develop nor retain a vertebral column (commonly known as a ''spine'' or ''backbone''), which evolved from the notochord. It is a paraphyletic grouping including all animals excluding the chordata, chordate s ...
s and
vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...
animals. This is the Amazon Basin's center of diversity for palms. The rare palm '' Itaya amicorum'' is found on the upper Javari River. 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 Suidae, pig, with a short, prehensile nose trunk (proboscis). Tapirs inhabit jungle and forest regions of South America, South and Centr ...
s ('' Tapirus terrestris''),
jaguar The jaguar (''Panthera onca'') is a large felidae, cat species and the only extant taxon, living member of the genus ''Panthera'' that is native to the Americas. With a body length of up to and a weight of up to , it is the biggest cat spe ...
s (''
Panthera onca The jaguar (''Panthera onca'') is a large cat species and the only living member of the genus ''Panthera'' that is native to the Americas. With a body length of up to and a weight of up to , it is the biggest cat species in the Americas a ...
''), the world's largest living rodents,
capybara The capybara or greater capybara (''Hydrochoerus hydrochaeris'') is the largest living rodent, native to South America. It is a member of the genus '' Hydrochoerus''. The only other extant member is the lesser capybara (''Hydrochoerus isthmi ...
s ('' Hydrochoerus hydrochaeris''), kinkajous ('' Potos flavus''), and white-lipped peccaries ('' Tayassu pecari''). 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 The ocelot (''Leopardus pardalis'') is a medium-sized spotted Felidae, wild cat that reaches at the shoulders and weighs between on average. It is native to the southwestern United States, Mexico, Central America, Central and South America, ...
''). Pygmy marmosets ('' Cebuella pygmaea''), Goeldi marmosets ('' Callimico goeldii''), pacaranas ('' Dinomys branickii''), and eastern lowland olingos ('' Bassaricyon alleni'') are found here, but not in regions to the east. Other primates present include tamarins ('' Saguinus fuscicollis'' and '' Saguinus imperator''), brown pale-fronted capuchins ('' Cebus albifrons''), squirrel monkeys ('' Saimiri sciureus''), white-faced sakis ('' Pithecia irrorata''), and black spider monkeys ('' Ateles paniscus''). The rare red uakari monkeys ('' Cacajao calvus'') are found in the north in swamp forests. Nocturnal two-toed sloths ('' Choloepus hoffmanni'') are well distributed throughout this region along with the widespread three-toes sloths ('' Bradypus variegatus''). 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 and destruction 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. Ab ...
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 River, Tambopata and Madre de Dios River, Madre de Dios rivers. The latter river joins the Madeira ...
, and Rio Branco. Manú National Park, a
World Heritage Site World Heritage Sites are landmarks and areas with legal protection under an treaty, international treaty administered by UNESCO for having cultural, historical, or scientific significance. The sites are judged to contain "cultural and natural ...
, protects of pristine lowland forest in southern Peru, a large part of which falls into this ecoregion. The nearby Tambopata-Candamo 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 monkeys, jaguars, capybaras, white-lipped peccaries, monkeys,
caimans A caiman ( (also spelled cayman) from Taíno language, Taíno ''kaiman'') is an alligatorid belonging to the subfamily Caimaninae, one of two primary lineages within the Alligatoridae family (biology), family, the other being alligators. ...
and river turtles. The Manuripi-Heath Amazonian Wildlife National Reserve 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 and Alto Juruá Extractive Reserve, are actively managed in Brazil. Other protected areas include national parks ( Serra do Divisor National Park, Madidi National Park, Isoboro Secure National Park, Bahuaja-Sonene National Park), national forests, Rio Acre Ecological Station, 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 ('' Tapirus terrestris'') and large
primates Primates is an order of mammals, which is further divided into the strepsirrhines, which include lemurs, galagos, and lorisids; and the haplorhines, which include tarsiers and simians ( monkeys and apes). Primates arose 74–63  ...
in the north. Some habitat is threatened by expansion of the agricultural and pastoral frontier,
gold mining Gold mining is the extraction of gold by mining. Historically, mining gold from Alluvium, alluvial deposits used manual separation processes, such as gold panning. The expansion of gold mining to ores that are not on the surface has led to mor ...
, and selective
logging Logging is the process of cutting, processing, and moving trees to a location for transport. It may include skidder, skidding, on-site processing, and loading of trees or trunk (botany), logs onto logging truck, trucksEuterpe precatoria'' 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 ''Cedrela'' is a genus of several species in the mahogany family, Meliaceae. They are evergreen or dry-season deciduous trees with pinnate leaves, native to the tropical and subtropical New World, from southern Mexico south to northern Argentina ...
''), and kapok (''
Ceiba pentandra ''Ceiba pentandra'' is a tropical tree of the order (biology), order Malvales and the family (biology), family Malvaceae (previously emplaced in the family Bombacaceae), native to Mexico, Central America and the Caribbean, northern South America, ...
''). During the period from 2004 to 2011 the ecoregion experienced an annual rate of habitat loss of 0.17%.


References


Sources

* *


Further reading

*Daly, D. C., and J. D. Mitchell. 2000. "Lowland vegetation of tropical South America". Pages 391–453 in D. L. Lentz, editor, ''Imperfect Balance: Landscape Transformations in the Precolumbian Americas''. New York: Columbia University Press. * *Ergueta S.P., and J. Sarmiento. 1992. "Fauna silvestre de Bolivia: diversidad y conservación". Pages 113–163 in M. Marconi, editor, ''Conservación de la Diversidad Biológica en Bolivia''. La Paz, Bolivia: CDC-Bolivia and USAID. *Fundação Instituto Brasilero de Geografia Estatástica-IBGE. 1993. ''Mapa de vegetação do Brasil''. Map 1:5,000,000. Rio de Janeiro, Brazil. *Henderson, A. 1995. ''The Palms of the Amazon''. New York: Oxford University Press. *Instituto Geográfico Nacional. 1987. ''Ecoregiones del Peru''. Map 1:5,000,000. Atlas del Peru, Lima, Peru. *Pacheco, V., and E. Vivar. 1996. "Annotated checklist of the non-flying mammals at Pakitza, Manu Reserve Zone, Manu National Park, Perú." Pages 577–592 in D. E. Wilson and A. Sandoval, editors, ''Manu: The Biodiversity of Southeastern Peru''. Washington, DC: Smithsonian Institution. *Peres, C. A. 1999. "The structure of nonvolant mammal communities in different Amazonian forest types". Pages 564–581 in J. F. Eisenberg and K. H. Redford, editors, ''Mammals of the Neotropics: the Central Neotropics''. Chicago: University of Chicago Press. {{ISBN, 0-226-19542-2 *Räsänen, M. 1993. "La geohistória y geología de la Amazonia Peruana". Pages 43–67 in R. Kalliola, M. Puhakka, and W. Danjoy, editors, ''Amazonia Peruana: vegetacióon húmeda tropical en el llano subandino''. Turku: PAUT and ONERN. *Ribera Arismendi, M. 1992. "Regiones ecológicas." Pages 9–71 in M. Marconi, editor, ''Conservación de la Diversidad Biológica en Bolivia''. La Paz, Bolivia: CDC-Bolivia and USAID. *Ribera, M.O., M. Libermann, S. Beck, and M. Moraes. 1994. ''Mapa de la vegetacion y areas protegidea de Bolivia.'' 1:1,500,000. Centro de Investigaciones y Manejo de Recursos Naturales (CIMAR) and Universidad Autónoma Gabriel Rene Moreno (UAGRM), La Paz, Bolivia. *Silva, J.M. C. 1998. ''Um método para o estabelecimento de áreas prioritárias para a conservação na Amazônia Legal.'' Report prepared for WWF-Brazil. 17 pp. Amazon rainforest Upper Amazon Flora of the Amazon Ecoregions of Bolivia Ecoregions of Brazil Amazon biome Ecoregions of Peru Neotropical tropical and subtropical moist broadleaf forests