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The Apure–Villavicencio dry forests (NT0201) is an ecoregion in Venezuela and Colombia to the east of the eastern cordillera of the
Andes The Andes ( ), Andes Mountains or Andean Mountain Range (; ) are the List of longest mountain chains on Earth, longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range ...
. The ecoregion covers the transition zone between montane forests in the Andes and the
llanos The Llanos ( Spanish ''Los Llanos'', "The Plains"; ) is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, ...
, or lowland grasslands. It has been severely degraded by deforestation, farming and ranching. The remnants are poorly protected.


Geography


Location

The Apure–Villavicencio dry forests ecoregion runs along the eastern edge of the Andes of Colombia and Venezuela from the southwest to the northeast. It has an area of . It forms a broad band between the mountains and grasslands in the north that becomes narrower further south. In Venezuela it covers parts of the states of Portuguesa, Barinas, and
Apure Apure State (, ) is one of the 23 States of Venezuela, states of Venezuela. Its territory formed part of the provinces of Mérida (state), Mérida, Maracaibo, and Barinas (state), Barinas, in accordance with successive territorial ordinations ...
, and in Colombia it lies in the departments of Arauca, Casanare, and Meta. Along the southeast and northern margin the dry forests ecoregion gives way to the
Llanos The Llanos ( Spanish ''Los Llanos'', "The Plains"; ) is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, ...
ecoregion. To the northwest it merges into the Venezuelan Andes montane forests along the Venezuelan Andes, and the Cordillera Oriental montane forests along the Cordillera Oriental of the Colombian Andes. In the extreme south it merges into the Caquetá moist forests.


Terrain

The Apure–Villavicencio dry forests ecoregion has an elevation of above sea level, sloping up from the plains to the base of the mountains. In the departments of Casanare and Arauca there are alluvial fans that extend to the Llanos, with heavily drained soils that are acid and infertile.


Climate

The
Köppen climate classification The Köppen climate classification divides Earth climates into five main climate groups, with each group being divided based on patterns of seasonal precipitation and temperature. The five main groups are ''A'' (tropical), ''B'' (arid), ''C'' (te ...
is "Aw": equatorial, winter dry. Annual average rainfall is . Temperatures range from . At a sample location at coordinates yearly average mean temperature is just over . Mean monthly temperatures are fairly constant, ranging from in July to in March.


Ecology

The ecoregion is in the
neotropical The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeogra ...
realm, in the
tropical and subtropical dry broadleaf forests The tropical and subtropical dry broadleaf forest is a habitat (ecology), habitat type defined by the World Wide Fund for Nature and is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-roun ...
biome. The forested lowland area in Venezuela between the Uribante and Arauca rivers at of elevation has been described as a
Pleistocene The Pleistocene ( ; referred to colloquially as the ''ice age, Ice Age'') is the geological epoch (geology), epoch that lasted from to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was fin ...
forest refuge with flora of the tropical lowlands.


Flora

The ecoregion is a transitional habitat between the montane forests of the Andes and the grasslands of the lowlands to the east, There are high levels of natural fragmentation of the seasonally dry tropical forests in the ecoregion. It originally contained a patchwork of premontane forest, gallery forest, dry forest and savanna. The plant formations have been much changed by humans. They include tall grassland, native semi-deciduous woodland and, mostly in Venezuela, deciduous thorn forest. Species include '' Caesalpinia conaria'', '' Cynophalla hastata'', '' Capparis brasiletto'', '' Cercidium praecox'', '' Chloroleucon mangense'', '' Coccoloba ramosissima'', '' Jacquinia'' species, '' Mimosa'' species, '' Piptadenia flava'', '' Poponax flexuosa'', '' Poponax tortuosa'' and '' Prosopis juliflora''. Species in the semi-deciduous woodland include '' Attalea maracaibensis'', '' Pachira quinata'', ''
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, ...
'', '' Cordia'' species, '' Crysophyllum sericeum'', '' Guazuma tormentosa'', '' Gustavia poeppigiana'', '' Inga'' species, '' Macrolobium'' species, ''
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 ...
'', '' Pouteria anibaefolia'', '' Roystonea venezuelana'', ''
Spondias mombin ''Spondias mombin'', also known as yellow mombin, hog plum, amra or cajazeira, is a species of tree and flowering plant in the family Anacardiaceae. It is native to the tropical Americas, including the West Indies. The tree was introduced by the ...
'', '' Tabebuia rosa'' and '' Trichilia maynasiana''. Species in the tall grasslands include '' Acrocomia aculeata'', '' Andropogon selloanus'', '' Axonopus canescens'', '' Byrsonima crassifolia'', '' Byrsonima coccolobifolia'', '' Curatella americana'' and ''
Trachypogon plumosus ''Trachypogon'' is a small genus of African and Latin American plants in the Poaceae, grass family. Crinkleawn grass is a common name for plants in this genus. ; Species * ''Trachypogon chevalieri'' (Stapf) Jacq.-Fél. – western and central Af ...
''. The Uribante–Arauca forest refuge in Venezuela holds Amazon region species such as '' Capparis sola'', '' Licania latifolia'', '' Dichapetalum latiflium'', '' Henrietella rimosa'', '' Leandra aristigera'', '' Maxillaria equitans'' and '' Piper hermannii''. Plant species found only in the refuge are '' Inga thibaudiana'', '' Machaerium paraense'', '' Ormosia nobilis'', '' Pterocarpus santalinoides'', '' Miconia matthaei'', '' Simaba paraensis'' and '' Aegiphila scandens''. The Colombian alluvial fans holds 72 families of flora with 173 genera and 232 species. The family
Rubiaceae Rubiaceae () is a family (biology), family of flowering plants, commonly known as the coffee, madder, or bedstraw family. It consists of terrestrial trees, shrubs, lianas, or herbs that are recognizable by simple, opposite leaves with Petiole ( ...
has 59 species and the family
Poaceae Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivate ...
has 37 species.


Fauna

Fauna in the Colombian alluvial fans include 65 species of reptiles and 144 species of birds. Characteristic mammals include the Guajira mouse opossum (''Marmosa xerophila''), Hummelinck's vesper mouse (''Calomys hummelincki'') and the
giant anteater The giant anteater (''Myrmecophaga tridactyla'') is an Insectivore, insectivorous mammal native to Central America, Central and South America. It is the largest of the four living species of anteaters, which are classified with sloths in the or ...
(''Myrmecophaga tridactyla''). Endangered mammals include Geoffroy's spider monkey (''Ateles geoffroyi'') and mountain tapir (''Tapirus pinchaque''). Endangered amphibians include the frogs Allobates juanii and Allobates ranoides.


Status

According to the IUCN Red List of Ecosystems the Llanos seasonal dry forests are considered "Endangered" due to historic declines in forest cover. The
World Wildlife Fund The World Wide Fund for Nature (WWF) is a Swiss-based international non-governmental organization founded in 1961 that works in the field of wilderness preservation and the reduction of human impact on the environment. It was formerly named the ...
gives the Apure-Villavicencio dry forests ecoregion a status of "Vulnerable". Much of the original habitat has been deforested and replaced by farms and livestock ranches. The illegal cultivation of
coca Coca is any of the four cultivated plants in the family Erythroxylaceae, native to western South America. Coca is known worldwide for its psychoactive alkaloid, cocaine. Coca leaves contain cocaine which acts as a mild stimulant when chewed or ...
has degraded the environment in Colombia. On the Venezuela-Colombia border oil refineries have polluted the groundwater and the
Arauca River The Arauca River () rises in the Andes Mountains of north-central Colombia and ends at the Orinoco in Venezuela. For part of its run it is the boundary between Colombia and Venezuela. The major city on its banks is Arauca, Arauca, Arauca, Col ...
with high levels of sodium. As of 2002 of the original in Colombia and Venezuela an area of had been converted to agriculture (including ranching), leaving , or 22.5%, with natural cover or extractive uses. Land use and land cover in Colombia were mapped between 2001 and 2010 using satellite images. There were net gains in 820 municipalities, mostly the moist forest biome, but net losses in 264 municipalities. The greatest loss of woody vegetation occurred in the Apure-Villavicencio ecoregion and the Llanos. A total of of woody vegetation was lost from the dry forests. The cause was expansion of intensive agriculture and cattle pasture, particularly in the foothills of the Arauca department. A 2006 book reported that 4.8% of the ecoregion was protected. The Sierra Nevada National Park in the north of the region protects
páramo Páramo () may refer to a variety of alpine tundra ecosystems located in the Andes Mountain Range, South America. Some ecologists describe the páramo broadly as "all high, tropical, montane vegetation above the continuous timberline". A narrower ...
and moist forest as well as some dry forest. The Serranía de la Macarena National Park includes savanna, dry forest, tropical lowland forest and montane forest. Parts of the park have been damaged by migrants and by poor management. The Tinigua National Park between the Serranía de la Macarena and the Cordillera Oriental protects some dry forest, but mostly holds tropical lowland forest. The Serranía de la Macarena and Tinigua parks have been affected by logging and hunting.


Notes


Sources

* * * * * * * {{DEFAULTSORT: Ecoregions of Venezuela Ecoregions of Colombia Neotropical dry broadleaf forests