Biological diversity in the Tropical Andes

Published: March 6, 2009, 4:06 pm

Updated: March 21, 2012, 2:46 pm

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Biodiversity (main) Ecology (main)

Andean Condor. Source: Eric Miraglia

Map of Tropical Andes. (Source: Conservation International)

The richest and most diverse region on Earth, the Tropical Andes spans 1,542,644 km², from western Venezuela to northern Chile and Argentina, and includes large portions of Colombia, Ecuador, Peru, and Bolivia. Roughly bounded by the Tropic of Capricorn in the south and the end of the Andes range in Colombia and Venezuela in the north, the region follows the tropical portion of the Andes Mountains and several adjoining cordilleras.

The Tropical Andes Hotspot extends downward to an elevation of 1,000 meters in the west, where it borders the Tumbes-Chocó-Magdalena Hotspot. In the east, the hotspot reaches down to 500 meters in elevation, a cutoff between the forests of the Andean slopes and the Amazonian lowlands.

The great highs and lows of the Andes mountain range, with its snowcapped peaks, steep slopes, deep canyons, and isolated valleys, have led to the evolution of an amazing diversity (Species diversity) of microhabitats and species. The Tropical Andes Hotspot contains the deepest gorge in the world — the 3,223-meter deep Cañón del Colca near Cabanaconde, Peru. The Andes also hold the highest large navigable lake in the world, Lake Titicaca, which sits at 3,810 meters on the Altiplano between Peru and Bolivia.

The Tropical Andes Hotspot is the richest and most diverse hotspot on Earth. Nearly half of its 40,000 plant species are endemic. (© Conservation International, photo by Roderic B. Mast)

The Tropical Andes are sometimes split into northern and southern zones, divided by an arid, east-west valley that runs roughly along the Ecuador-Peru border in the far northern portion of Peru. In this valley, which is called the Marañon Gap or Huancabamba Depression, altitudes drop to about 500 meters, creating an important barrier to faunal and floral dispersal in the region. In the north, the hotspot is naturally more complex and fragmented, with the main Andean chain dividing into three cordilleras in Colombia, including the isolated Sierra Nevada de Santa Marta (Colombia’s tallest mountain). In Venezuela, the Andes terminate with the Cordillera de la Costa, Cordillera de Caripe and Península de Paria in Venezuela.

Within the hotspot, different types of vegetation correspond to gradients in altitude. Tropical wet and moist forests occur between 500 and 1,500 meters. Various types of cloud forests extend from 800 to 3,500 meters, including the montane cloud forests (yungas, ceja de selva, or ceja de la montaña) that cover more than 500,000 km² in Peru and Bolivia and are among the richest and most diverse (Species diversity) forests on Earth. At higher altitudes (3,000-4,800 meters), grassland and scrubland systems reach up to the snow line. These ecosystems include the páramo, a dense alpine vegetation growing on a thick mat of sponge-like, highly absorbent mosses and grasses in the cold, humid reaches of the northern Andes, and the drier puna, characterized by alpine bunchgrass species surrounded by herbs, grasses, sedges, lichens, mosses and ferns in the cold but dry southern Tropical Andes. In addition to these main ecosystems, there are also patches of dry forests, woodlands, cactus stands, thornscrub, and matorral found in this hotspot.

Unique Biodiversity

Plants

The Tropical Andes is home to an estimated 30,000-35,000 species of vascular plants, accounting for about 10 percent of all the world's species and far surpassing the diversity of any other {C}{C}hotspot. It is also the world leader in plant {C}{C}endemism, with an estimated 50 percent (and perhaps 60 percent or more) of these species found nowhere else on Earth. This means that nearly seven percent of the world's vascular plants are endemic to the 0.8 percent of the Earth’s land area represented by this hotspot. These numbers are only conservative estimates and are likely to be greater; between 1999 and 2003, nearly 450 new plant species were described from the Ecuadorian portion of the hotspot alone. There are also approximately 330 endemic genera, and a single endemic family, the Columelliaceae.

Describing the diversity and endemism of the world's richest flora cannot be accomplished in a single paragraph. However, a few important trends should be noted. The forests of the Tropical Andes are floristically different from their lowland counterparts in that they contain significant representation of Laurasian plant families and genera not found in the lowlands, as well as Gondwana-derived taxa. In general, diversity decreases with altitude within this hotspot, and endemism increases. However, the puna and parámo grasslands that extend from the cloud forests to the snow line are still very diverse, harboring as many as 800 species, many of these local endemics.

The region is home to a number of unusual plant species, including a type of high Andean bromelilad (Puya raimondii) that takes as much as a century to reach maturity, and an endemic palm species (Parajubaea torallyi, EN), that grows at the highest altitude of any palm on Earth (3,400 meters). The hotspot is also the center of origin for some of world's most important crops, including tobacco and potatoes, as well as the cinchona plant, which is the source of quinine. However, agriculture and timber production have imperiled significant portions of this hotspot; the magnificent Podocarpus-dominated cloud forests are largely gone.

Vertebrates

Birds

A male Andean cock-of-the-rock (Rupicola peruviana) displays in the cloud forest to attract a nearby female. (© André Bärtschi Vaduz)

The Tropical Andes harbor more than 1,700 bird species, nearly 600 of which are endemic, a level of endemism that is unequaled in the world. In addition, the region has 66 endemic bird genera, and includes all or part of 21 different Endemic Bird Areas, as defined by BirdLife International. To put these numbers in perspective, consider the hummingbirds (Trochilidae). The eastern continental United States is the summer breeding ground for one species, but in the Nariño department in southern Colombia (one quarter the size of New York state), there are over 100 resident hummingbird species.

At present, nearly 160 bird species in the Tropical Andes are threatened, and at least one species, the Colombian grebe (Podiceps andinus), has gone extinct in the last century. Highly threatened birds include blue-billed curassow (Crax alberti, CR), Niceforo’s wren (Thryothorus nicefori, CR), Fuertes’s parrot (Hapalopsittaca fuertesi, CR), black-breasted puffleg (Eriocnemis nigrivestis, CR), Kalinowski’s tinamou (Nothoprocta kalinowskii, CR), and royal cinclodes (Cinclodes aricomae, CR). The yellow-eared parrot (Ognorhynchus icterotis, CR), reportedly common across Colombia and Ecuador at the turn of the 20th century, survives in two small populations in the Colombian Andes. Here in the Quindío wax palm habitat (Ceroxylon quindiuense, VU), which is the species’ obligate habitat, ProAves Foundation is working on conservation initiatives that are buying the yellow-eared parrot a chance for survival.

The region is home to the spectacular Andean condor (Vultur gryphus), one of the largest flying birds on Earth. Hunted nearly to extinction, the condor is now making a comeback through conservation and reintroduction programs. The hotspot also boasts the greatest diversity of hummingbirds in the world, including the world's largest, the giant hummingbird (Patagona gigas), and the marvelous spatuletail (Loddigesia mirabilis, EN), appropriately named for its long racquet-shaped tail.

Mammals

The white-fronted capuchin monkey (Cebus albifrons) is among the rich primate fauna in the Tropical Andes Hotspot. (© Conservation International, photo by Russ Mittermeier)

There are nearly 570 mammal species in the Tropical Andes hotspot; about 75 of these are endemic and nearly 70 are threatened. The hotspot also has six endemic genera, each represented by only one species: Garlepp’s mouse (Galenomys garleppi), the Andean rat (Lenoxus apicalis), little or mountain coati (Nasuella olivacea), puna mouse (Punomys lemminus), and fish-eating rat (Anotomys leander, EN), a species known only from the Andes of northern Ecuador and highly specialized for an aquatic existence.

The sixth endemic genus is one of the most important mammalain flagship species for the Tropical Andes, the yellow-tailed woolly monkey (Oreonax flavicauda, CR), which was believed to be extinct until it was rediscovered in 1974. It is the largest mammal endemic to Peru, and is only one of three primate genera in the Neotropics to be endemic to a single country. It is restricted to a small area of cloud forest in the northern Peruvian departments of Amazonas and San Martín. Other large mammals found in the area include the woolly or mountain tapir (Tapirus pinchaque, EN) and the spectacled bear (Tremarctos ornatus, VU), which is the only bear in South America and is endemic to this hotspot.

The vicuña (Vicugna vicugna) – which along with the domesticated llama (Lama glama), the alpaca (Lama pacos), and the wild guanaco (Lama guanicoe) is one of four distinctive camel species found in the Tropical Andes – represents an important conservation success story for this hotspot. Considered to have one of the finest wools in the world, the vicuña was driven to the brink of extinction, until a sustainable-use program implemented in the 1970s led to its dramatic recovery.

Reptiles

There are more than 600 reptile species identified in the Tropical Andes hotspot (more than 270 of which are endemic) and three endemic genera, a level of endemism unequaled in the world for this class. The region's reptiles include the primitive tree boa (Corallus enydris), an arboreal snake which has a pelvis and vestigial hind limbs, and the Magdalena river turtle (Podocnemis lewyana, EN), found in the Rio Magdalena River basin.

Amphibians

The Andes is the most important region in the world for amphibians, with around 980 species and more than 670 endemics. Eight amphibian genera are endemic to the Andes. The most specious of these is the frog genus Telmatobius, with about 45 species. Many other non-endemic genera are highly speciose; the frog genus Eleutherodactylus has more than 330 species, of which more than 250 are restricted to the hotspot.

The best-known amphibians from the Tropical Andes are the brightly colored poison dart frogs from the family Dendrobatidae. Some of these frogs are among the most poisonous organisms on Earth; others, like Epipedobates tricolor, which produces a compound more powerful than that of morphine, hold promise as the source of new medicines.

Unfortunately, the amphibian fauna in the Tropical Andes is also among the most threatened; around 450 species are listed on the 2004 IUCN Red List as threatened, and more than 360 of these are endemic to the hotspot. Although habitat loss is playing a major role in driving many of these extinctions, disease, particularly due to the pathogenic chytrid fungus B. dendrobatidis has had devastating impacts on amphibian populations in this part of the world. The stream-dwelling harlequin frogs of the genus Atelopus have been especially affected – of the 60-odd species of Atelopus occurring in this hotspot, 56 are considered Critically Endangered.

Freshwater Fishes

There are more than 375 documented species of freshwater fishes in the hotspot, and it is likely that many more will be found along the Amazonian flanks of the [[mountain]s]. Of these, more than 130 are endemic, including the members of the genus Orestias, which is represented by more than 40 unique species in Lake Titicaca and nearby drainages. All but a few of the 90 species of naked sucker-mouth catfishes in the family Astroblepidae are also endemic to the region.

Human Impacts

A mahogany saw mill in the Chimane Forest near Beni, Bolivia. (© Conservation International, photo by Haroldo Castro)

Human communities, including the great empire of the Incas, have lived in the Tropical Andes for thousands of years. Because the Inter-Andean valleys are the most hospitable to people, they are also the most degraded parts of the hotspot, with less than 10 percent of their original habitat remaining. At the other end of the spectrum, some of the least degraded parts of the hotspot include isolated [[region]s] in Venezuela and Colombia, and the eastern slope of the Andes in Bolivia, Peru, and parts of Ecuador. In Peru and Bolivia particularly, time still exists to establish reserves in areas of intact primary forests. However, the effects of a large and growing population continue to threaten biodiversity in the Tropical Andes. Several cities with millions of inhabitants, including Santa Fe de Bogotá, Colombia; Quito, Ecuador; Arequipa, Peru; and La Paz/El Alto, Bolivia, are located within the hotspot and continue to expand as their populations grow. In total, it is thought that no more than about 25 percent of the original vegetation of this hotspot remains intact.

In the cloud forests, agriculture, deforestation, dams, and road building are the most significant threats. At higher altitudes, seasonal burning, grazing, agriculture, mining, and fuelwood collection have degraded the grasslands and scrublands of the puna and páramos. Extensive cultivation of opium poppy has led to the clearing of thousands of hectares of montane forests and the spread of chemical herbicides through rivers and [[stream]s] that pose additional threats to plant and animal species, especially amphibians. Guerilla activities associated with this trade often make it difficult to sustain conservation activities in the area safely.

In the lower altitudes, a new and serious threat is oil exploration and development on the eastern slopes of the Andes and the adjacent Amazonian lowlands of Colombia, Ecuador, Peru, and Bolivia. In recent decades, large oil and gas discoveries have been made in these areas, making the region a hydrocarbon hotspot as well as a biodiversity hotspot. Industrial and small-scale mining for diamonds, iron ore, gold, and bauxite also pose threats throughout the hotspot. The growing network of roads that accompanies this industrial development is also bringing waves of migrants fleeing economic hardship in the highlands.

Finally, invasive alien species, many of which were introduced as human food sources or to facilitate agriculture, threaten the survival of native flora and fauna. Alien species include exotic grasses used for cattle grazing, the rainbow trout (Salmo gairdnerii), and the American bullfrog (Rana catesbeiana), which can out-compete or even eat many native amphibians.

Conservation Action

A Quechua woman and girls with their llamas at the Inca fortress of Sacsayhuaman near Cusco, Peru. (© Conservation International, photo by Jim Nations)

Despite the high level of threat in the Tropical Andes, a network of protected areas today conserves some of the most important remaining intact ecosystems in the hotspot. Protected areas cover some 16 percent of the original extent of vegetation in the region, although only about eight percent of the hotspot is protected in reserves or parks in IUCN categories I to IV. However, even these parks are not inviolate, and without adequate enforcement and monitoring, they can be damaged by settlement, poaching, and illegal logging.

One method for identifying priority areas for the expansion of protected area networks is by identifying sites for species that face the greatest risk of global extinction. Globally threatened species are best protected through the conservation of sites in which they occur; these sites are referred to as “key biodiversity areas” (KBAs). KBAs are discrete biological units that contain one or more globally threatened or restricted-range species, and can potentially be managed for conservation as a single unit. In the Tropical Andes hotspot, Conservation International and the BirdLife International partnership recently completed the identification of Important Bird Areas (IBAs) which provide a starting point for incorporation of other taxonomic groups as we continue in the identification of KBAs throughout the region.

Because research has shown that small parks may not adequately protect biodiversity in the long term, conservation efforts in the Tropical Andes have focused on the need to add to and connect this network of protected areas. By connecting existing parks through corridors of protected areas and biodiversity-friendly, sustainable development projects, ecological processes like migration, dispersal, and gene flow among populations are enhanced. Conservation International has begun the implementation of the Cóndor-Kutukú Conservation Corridor, for example, that includes the following areas in Ecuador: Podocarpus National Park, Sangay National Park, Condor National Park, Cordillera de Kutukú and Cordillera del Cóndor. In Peru, the Corridor includes Santiago-Comaina Reserved Zone, Tabaconas-Namballe National Sanctuary and Cordillera Azul National Park.

The most impressive conservation corridor in the Tropical Andes, and one of the largest in the world, has been slowly taking shape in the last few decades in southern Peru and adjacent parts of Bolivia, along the interface between the Andean and Amazonian [[region]s]. This corridor begins in Peru's Manú National Park, which at 18,812 km² is one of the largest rainforest reserves on Earth, and stretches through the 3,250-km² Bahuaja-Sonene National Park, parts of the Tambopata-Candamo Reserved Zone in Peru, and across the Bolivian border to the 19,000-km² Madidi National Park. From Madidi, the chain of protected areas continues with the Pilón Lajas Biosphere Reserve, the Chimane Indigenous Territory, the Beni Biosphere Reserve, and the Ulla Ulla reserve. The future of this promising biodiversity corridor depends heavily on effective implementation and enforcement of protective measures.

In recent years, a series of major conservation investments have contributed to conservation efforts in the Tropical Andes. For example, the Critical Ecosystem Partnership Fund (CEPF) has committed to investing US$6 million in the Vilcabamba-Amboró Corridor in Peru and Ecuador, and the Global Conservation Fund has invested US$1.3 million in projects that have led to the creation of nearly 30,000 km² of new protected areas in the hotspot. Included in the projects supported by the GCF were two debt-for-nature swaps, one in Peru in 2003 and another in Colombia in 2004. Both of these were carried out in partnership with the World Wildlife Fund, The Nature Conservancy, and the United States Government; they will provide US$10.6 million to 10 sites in Peru and US$10 million to five sites in Colombia over a 12-year period.

Other conservation efforts in the region include projects to mitigate the direct effects of large-scale infrastructure development and resource extraction, programs for the conservation and rehabilitation of specific species such as the Andean condor and the yellow-eared parrot, public awareness and participation, and the development of already degraded areas for agricultural production, rather than clearing standing forests.

Notes This article is based on contributions from Jose Vicente Rodriguez Mahecha, Paul Salaman, Peter Jorgensen, Trisha Consiglio, Eduardo Forno, Antonio Telesca, Luis Suarez, Fabio Arjona, Franklin Rojas, Robert Bensted-Smith, and Victor Hugo Inchausty.. For a complete list of all contributors to the Biodiversity Hotspot program, see Biodiversity Hotspot Site Credits (Biological diversity in the Tropical Andes) .

Further Reading

• Albuja, V.L. & Patterson, B.D. 1996. A new species of northern shrew-opossum (Paucituberculata: Caenolestidae) fom the Cordillera del Cóndor, Ecuador. Journal of Mammology, 77:41-53.
• Brako, L. & Zarucchi, J.L. 1993. Catalogue of the flowering plants and gymnosperms of Peru. Monogr. Syst. Bot., Missouri Botanical Garden, 45: 1-1286.
• Castro, H. 1996. Volver a Tambopata. A Communications Strategy. Washington, DC.: Conservation International.
• Cuatrecasas, J. 1958. Aspectos de la vegetación natural de Colombia. Revista de la Academia Colombiana de Ciencias Exactas, Físicas y Naturales, 10: 221-264.
• Dodson, C.H. & Gentry, A.H. 1991. Biological extinction in western Ecuador. Annals Missouri Botanical Garden, 78:273-295.
• Gentry, A.H. 1977. Endangered plant species and habitats of Ecuador and Amazonian Peru. In G.T. Prance & T.S. Elias. (Eds.), Extinction is Forever. pp. 136- 149. New York: New York Botanical Garden.
• Gentry, A.H. 1990. La región Amazónica. In C.C. Uribe et. al., Selva húmeda de Colombia. Villegas, Bogotá.
• Goering, L. 1998. Tiny Frog Offers Major Painkiller: Drug Research Finds. In Chicago Tribune, August 30, 1998.
• Guhl, E. 1982. Los Páramos Circundantes de la Sabana de Bogotá. Bogotá, Colombia: Jardín Botánico José Celestino Mutis.
• Jørgensen, P.M. & León-Yánez, S. (Eds.). 1999. Catalogue of the vascular plants of Ecuador. Syst. Bot. Missouri Bot. Gard. 75: i–vii, 1–1181. ISBN: 0915279606
• Kessler, M. 2000. Elevational gradients in species richness and endemism of selected plant groups in the central Bolivian Andes. Plant Ecology, 149: 181-193.
• Kessler, M. 2002. The elevational gradient of Andean plant endemism: Varying influences of taxon-specific traits and topography at different taxonomic levels. J Biogeography, 29:1159-1165.
• Langendoen, D. & Gentry, A.H. 1991. The structure and diversity of rain forests at Bajo Calima, Chocó region, western Colombia. Biotropica, 23: 2-11.
• Luteyn, J.L. 1999. Páramos: A checklist of plant diversity, geographical distribution, and botanical literature. Memoirs of the New York Botanical Garden. 84: i-xv, 1-278, color plates I-VI.
• Mast, R.B., Mittermeier, R.A. & Rodríguez-Mahecha, J.V. 1996. El Embrujo de Tambopata. Caretas, Lima, Peru.
• Mast, R.B., Rodríguez-Mahecha, J.V., Mittermeier, R.A. & Mittermeier, C.G. 1997. Colombia. In R. A. Mittermeier, P. Robles Gil & C. G. Mittermeier. (Eds.), Megadiversity: Earth’s Biologically Wealthiest Nations. pp. 108-127. Monterrey, Mexico: CEMEX. ISBN: 9686397507
• Mast, R.B., Mittermeier, C.G., Mittermeier, R.A., Rodríguez-Mahecha, J.V. & Hemphill, A.H. 1997. Ecuador. In R. A. Mittermeier, P. Robles Gil & C. G. Mittermeier. (Eds.), Megadiversity: Earth’s Biologically Wealthiest Nations. pp. 314-324. Monterrey, Mexico: CEMEX. ISBN 9686397507.
• Mittermeier, R.A., Mast, R.B., del Prado, C.P. & Mittermeier, C.G. 1997. Peru. In R.A. Mittermeier, P. Robles Gil & C.G. Mittermeier. (Eds.), Megadiversity: Earth’s Biologically Wealthiest Nations. pp. 282-297. Monterrey, Mexico: CEMEX. ISBN 9686397507.
• Moraes R.M. 1996. Novelties of the genera Parajubaea and Syagrus (Palmae) from interandean valleys of Bolivia. Novon 6: 85-92.
• Rodriguez-Mahecha, J.V., Hernández-Camacho, J.I., Defler, T.R., Alberico, M., Mast, R.B., Mittermeier, R.A. & Cadena, A. 1995. Mamíferos Colombianos: Sus Nombres Comunes e Indígenas. Occasional Paper No. 3. Occasional Papers in Conservation Biology. Washington, DC.: Conservation International.
• Ron, S. R., Duellman, W. E., Coloma, L. A., & Bustamante, M. R. 2003. Population decline of the Jambato toad Atelopus ignescens (Anura: Bufonidae) in the Andes of Ecuador. Journal of Herpetology, 37:116-126.
• Sklenár, P., Luteyn, J.L., Ulloa Ulloa, C., Jørgensen, P.M. & Dillon, M.O. 2005. Flora genérica de los páramos - Guía ilustrada de plantas vasculares. Memoirs of the New York Botanical Garden, 92. 500 Pp.
• Stotz, D.F., Fitzpatrick, J.W., Parker, T.A, III. & Moskovits, D.K. 1996. Neotropical Birds: Ecology and Conservation. London: The University of Chicago Press, Ltd. ISBN: 0226776301
• Ulloa Ulloa C. & Jørgensen, P.M. 1993. Arboles y arbustos de los Andes del Ecuador. AAU Reports, 30:1-264.
• Ulloa Ulloa, C., Zarucchi, J.L. & León, B. 2004. Diez años de adiciones a la flora del Perú: 1993-2003. Arnaldoa Ed. Especial, Nov. 2004: 1-242.
• Ulloa Ulloa, C. & Jørgensen, P.M. 2005. Endemic plant genera of the Tropical Andes. Database v. Jan 2005. Missouri Botanical Garden.
• van der Werff, H. & Consiglio, T. 2004. Distribution and Conservation Significance of Endemic Species of Flowering Plants in Peru. Biodiversity and Conservation. In press.
• WWF. 1997. WWF 2000. The Living Planet Campaign. Washington, D.C.: World Wildlife Fund.
• Young, K., Ulloa Ulloa, C. Luteyn, J.L. & Knapp, S. 2002. Plant evolution and endemism in Andean South America: An indroduction. Bot. Rev., 68(1):4-21.

Disclaimer: This article is taken wholly from, or contains information that was originally published by, the Conservation International. Topic editors and authors for the Encyclopedia of Earth may have edited its content or added new information. The use of information from the Conservation International should not be construed as support for or endorsement by that organization for any new information added by EoE personnel, or for any editing of the original content.

Citation

International, C. (2012). Biological diversity in the Tropical Andes. Retrieved from http://editors.eol.org/eoearth/wiki/Biological_diversity_in_the_Tropical_Andes