# Llanos
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{{Short description|Tropical grassland ecoregion in Colombia and Venezuela}}
{{About|the grassland and savanna region in South America||Llanos (disambiguation)}}
{{Infobox ecoregion
|name = Llanos
|image = Los Llanos Colombia by David.png
|caption = The Llanos in [Colombia](/source/Colombia)
|map = Ecoregion NT0709.svg
|map_caption = Location of the Llanos
|biogeographic_realm = [Neotropical](/source/Neotropical_realm)
|biome = [tropical and subtropical grasslands, savannas, and shrublands](/source/tropical_and_subtropical_grasslands%2C_savannas%2C_and_shrublands)
|border = [Apure–Villavicencio dry forests](/source/Apure%E2%80%93Villavicencio_dry_forests)
|border1 = [Guianan lowland moist forests](/source/Guianan_lowland_moist_forests)
|border2 = [Guianan piedmont and lowland moist forests](/source/Guianan_piedmont_and_lowland_moist_forests)
|border3 = [La Costa xeric shrublands](/source/La_Costa_xeric_shrublands)
|border4 = [Orinoco wetlands](/source/Orinoco_wetlands)
|border5 = [Negro-Branco moist forests](/source/Negro-Branco_moist_forests)
|country = {{COL}}
|country1 = {{VEN}}
|area = 375,786
|conservation = Vulnerable
|protected = 105,323 km² (28
|protected_ref = )[Eric Dinerstein, David Olson, et al. (2017). An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm, BioScience, Volume 67, Issue 6, June 2017, Pages 534–545; Supplemental material 2 table S1b. [https://doi.org/10.1093/biosci/bix014]]
|embedded =
}}
The '''Llanos''' ([Spanish](/source/Spanish_language) ''Los Llanos'', "The Plains"; {{IPA|es|los ˈʝanos}}) is a vast tropical grassland [plain](/source/plain) situated to the east of the [Andes](/source/Andes) in [Colombia](/source/Colombia) and [Venezuela](/source/Venezuela), in northwestern South America. It is an [ecoregion](/source/ecoregion) of the [tropical and subtropical grasslands, savannas, and shrublands](/source/tropical_and_subtropical_grasslands%2C_savannas%2C_and_shrublands) biome.
==Geography==
The Llanos occupy a lowland that extends mostly east and west. The Llanos are bounded on the west and northwest by the [Andes](/source/Andes), and on the north by the [Venezuelan Coastal Range](/source/Venezuelan_Coastal_Range). The [Guiana Highlands](/source/Guiana_Highlands) are to the southeast, and the [Negro-Branco moist forests](/source/Negro-Branco_moist_forests) are to the southwest. To the east the [Orinoco wetlands](/source/Orinoco_wetlands) and [Orinoco Delta swamp forests](/source/Orinoco_Delta_swamp_forests) occupy the [Orinoco Delta](/source/Orinoco_Delta).[{{WWF ecoregion|id=nt0709|name=Llanos}}] The Llanos' main river is the [Orinoco](/source/Orinoco), which runs from west to east through the ecoregion and forms part of the [Colombia–Venezuela border](/source/Colombia%E2%80%93Venezuela_border). The Orinoco is the major river system of Venezuela.[{{cite book|title=Earth|publisher=Doring Kindersley|year=2003|pages=328|isbn=1-4053-0018-3}}]
A 2017 assessment found that 105,323 km², or 28%, of the ecoregion, is in protected areas.[UNEP-WCMC (2020). Protected Area Profile for Venezuela (Bolivarian Republic of) from the World Database of Protected Areas, September 2020. Available at: www.protectedplanet.net]
==Climate==
The ecoregion has a [tropical savanna climate](/source/tropical_savanna_climate) that grades into a [tropical monsoon climate](/source/tropical_monsoon_climate) in the Colombian Llanos. Rainfall is seasonal, with a [rainy season](/source/Wet_season) from April to November, and a [dry season](/source/dry_season) between December and March. The wettest months are typically June and July. Rainfall varies across the ecoregion, from up to {{convert|3000|mm|in|-1}} per year in the southwest, {{convert|1200|to|1600|mm|in|-0}} in [Apure](/source/Apure) State, and {{convert|800|to|1200|mm|in|-0}} per year in [Monagas](/source/Monagas) State in the northeast. Mean annual temperature is {{convert|27|°C|°F|1|disp=or}}, and the average monthly temperature varies little throughout the year; the lowest-temperature months (June, July, December, and January) are only {{convert|2|C-change|F-change|1|disp=or}} cooler than the hottest months.[
==Flora==
The plant communities in the Llanos include open grasslands, [savanna](/source/savanna) with scattered trees or clumps of trees, and small areas of forest, typically [gallery forest](/source/gallery_forest)s along rivers and streams. There are seasonally flooded grasslands and savannas (''llano bajo'') and grasslands and savannas that remain dry throughout the year (''llano alto'').][
The llano alto grasslands and savannas are characterized by grasses and shrubs 30–100 cm high, forming [tussock](/source/tussock_(grass))s 10 to 30 cm apart. Soils are typically sandy and nutrient-poor. Llano alto covers approximately two-thirds of the Venezuelan llanos and is also widespread in the Colombian llanos. Grasses of genus ''[Trachypogon](/source/Trachypogon)'' are predominant, and species include ''[Trachypogon plumosus](/source/Trachypogon_plumosus), [T. vestitus](/source/Trachypogon_vestitus), [Axonopus canescens](/source/Axonopus_canescens), [A. anceps](/source/Axonopus_anceps), [Andropogon selloanus](/source/Andropogon_selloanus), [Aristida](/source/Aristida)'' spp., ''[Leptocoryphium lanatum](/source/Leptocoryphium_lanatum), [Paspalum carinatum](/source/Paspalum_carinatum), [Sporobolus indicus](/source/Sporobolus_indicus)'', and ''[S. cubensis](/source/Sporobolus_cubensis)'', and [sedge](/source/sedge)s in the genera ''[Rhynchospora](/source/Rhynchospora)'' and ''[Bulbostylis](/source/Bulbostylis)''. Shrubs and herbs are most commonly [legume](/source/legume)s in the genera ''[Mimosa](/source/Mimosa), [Cassia](/source/Cassia_(genus)), [Desmodium](/source/Desmodium), [Eriosema](/source/Eriosema), [Galactia](/source/Galactia), [Indigofera](/source/Indigofera), [Phaseolus](/source/Phaseolus), [Stylosanthes](/source/Stylosanthes), [Tephrosia](/source/Tephrosia)'', and ''[Zornia](/source/Zornia)''. The trees manteco (''[Byrsonima crassifolia](/source/Byrsonima_crassifolia)''), chaparro (''[Curatella americana](/source/Curatella_americana)''), and alcornoque (''[Bowdichia virgilioides](/source/Bowdichia_virgilioides)'') are the most common, growing either as scattered trees or in woodland patches known as ''matas'' which range in area from 12 meters in diameter up to a hectare.][
During the rainy season, parts of the Llanos can flood up to a meter. This turns some savannas and grasslands into temporary [wetland](/source/wetland)s, comparable to the [Pantanal](/source/Pantanal) of central South America. This flooding creates habitat for water birds and other wildlife. These seasonally flooded grasslands and savannas, known as llano bajo, typically have richer soils. They are characterized by the grass ''[Paspalum fasciculatum](/source/Paspalum_fasciculatum)''. Trees include the palm ''[Copernicia tectorum](/source/Copernicia_tectorum)'' and gallery forest species.][
Gallery forests include evergreen seasonally flooded forests, and semi-deciduous forests on higher ground. Morichales are seasonally flooded forests characterized by the [moriche palm](/source/Mauritia_flexuosa) (''Mauritia flexuosa''). Vegas are seasonally flooded evergreen forests found along the Orinoco and its tributaries. Trees form a canopy 8 to 20 meters high and include ''[Inga](/source/Inga)'' spp., ''[Combretum frangulifolium](/source/Combretum_frangulifolium), [Gustavia augusta](/source/Gustavia_augusta), [Pterocarpus](/source/Pterocarpus)'' sp., ''[Pterocarpus dubius](/source/Pterocarpus_dubius), [Spondias mombin](/source/Spondias_mombin)'', and ''[Copaifera pubiflora](/source/Copaifera_pubiflora)''.][ Semi-deciduous forests occur above flood level and form a canopy 12 to 15 meters high. Common trees include ''[Tabebuia billbergii](/source/Tabebuia_billbergii), [Godmania aesculifolia](/source/Godmania_aesculifolia), [Cassia moschata](/source/Cassia_moschata), Spondias mombin, Copaifera pubiflora, [Bourreria cumanensis](/source/Bourreria_cumanensis), [Cordia](/source/Cordia)'' spp., ''[Bursera simaruba](/source/Bursera_simaruba), [Cochlospermum vitifolium](/source/Cochlospermum_vitifolium), [Hura crepitans](/source/Hura_crepitans)'', and ''[Acacia glomerosa](/source/Acacia_glomerosa)''.][
The gallery forests are home to more diverse large and medium-sized mammals, including [collared peccary](/source/collared_peccary) (''Tayassu tajacu''), [white-lipped peccary](/source/white-lipped_peccary) (''T. pecari''), [South American tapir](/source/South_American_tapir) (''Tapirus terrestris''), white-tailed deer, [red brocket](/source/red_brocket) (''Mazama americana''), [wedge-capped capuchin](/source/wedge-capped_capuchin) (''Cebus olivaceus''), [Venezuelan red howler](/source/Venezuelan_red_howler) (''Alouatta seniculus''), large rodents like the [lowland paca](/source/lowland_paca) (''Cuniculus paca''), [agouti](/source/agouti)s (''[Dasyprocta](/source/Dasyprocta)'' spp.), and [Brazilian porcupine](/source/Brazilian_porcupine) (''Coendou prehensilis''), and large cats like the [puma](/source/cougar) (''Puma concolor''), [jaguar](/source/jaguar) (''Panthera onca''), and [ocelot](/source/ocelot) (''Leopardus pardalis''). The endangered [giant otter](/source/giant_otter) (''Pteronura brasiliensis'') lives along the Orinoco and its tributaries.][ Some of the [largest jaguars](/source/South_American_jaguar) in the world are found in the Llanos, with average weights of over {{convert|100|kg|lb|abbr=on}} for males.][{{cite journal |author1=Jedrzejewski, W. |author2=Abarca, M. R. |author3=Viloria, Á. |author4=Cerda, H. |author5=Lew, D. |author6=Takiff, H. |author7=Abadia, E. |author8=Velozo, P. |title=Jaguar conservation in Venezuela against the backdrop of current knowledge on its biology and evolution |publisher=Interciencia |format=pdf |volume=36 |issue=12 |pages=954–966 |url=https://www.researchgate.net/publication/220033215 |year=2011 |access-date=2019-07-12}}] The [Llanos long-nosed armadillo](/source/Llanos_long-nosed_armadillo) (''Dasypus sabanicola'') and the short-tailed opossum ''[Monodelphis orinoci](/source/Monodelphis_orinoci)'' are [endemic](/source/endemism) to the Llanos.[{{Cite web |last=Paz |first=Manuel María |author-link=Manuel María Paz |title=General View of The Plains, Province of Casanare |work=World Digital Library |access-date=2014-05-21 |url=http://www.wdl.org/en/item/9027}}] The term ''[llanero](/source/llanero)'' ("plainsman") became synonymous with the cowhands that took care of the herds and had some cultural similarities with the [gaucho](/source/gaucho)s of the [Pampas](/source/Pampas) or the ''[vaqueros](/source/Cowboy)'' of [Spanish](/source/Spanish_Texas) and [Mexican Texas](/source/Mexican_Texas). Decades of extensive cattle raising has altered the ecology of the Llanos. Grasslands and savannas are frequently burned to make them more suitable for grazing and eliminate trees and shrubs. Non-native grasses have been introduced for cattle fodder, including the African grass ''[Melinis minutiflora](/source/Melinis_minutiflora)'', and now cover large areas.