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(Tropical) Andes: CPD Site SA32

Peru and Ecuador

Location:  Andean slopes and valleys of northern Peru and southern Ecuador between latitudes 6°-4°30'S and longitudes 78°-79°40'W.
29,000 km².
c. 1000-4000 m.
Dry forest at lower elevations, montane cloud forest, páramo-like above 3200-3500 m.
At least 2000-2500 vascular plant species; northern or southern limit for many species; many endemic species.
Useful plants: 
Valuable timber species; fuelwood; medicinals, ornamentals.
Other values: 
Watershed protection; distributional limit for numerous species; habitats for many endemic fauna.
Logging, expansion of agricultural frontier.
1 National Sanctuary (295 km²).

Map 68: CPD Site SA32


The Huancabamba region (Map 68) is a mountainous area of moderate but complex relief of northern Peru and southernmost Ecuador in the general area where the Central Andes and the Northern Andes diverge. The general area is tectonically multifarious, with distinctive terranes and two transverse mega-shears (Feininger 1987; Clapperton 1993). The overall region is part of an Early Palaeozoic and Precambrian schist belt (Atherton, Pitcher and Warden 1983) that forms a complicated system of isolated low ranges and basins referred to as the Huancabamba Depression. Here the older Central Andes (Miocene to Pliocene) and younger Northern Andes (Late Pliocene to Pleistocene) fragment into ranges usually less than 3500 m high separated by valleys mostly between 1000-2000 m above sea-level; the continental divide dips to 2145 m at the Abra de Porculla. Huancabamba also refers to a Peruvian province in the Department of Piura that lies at the headwaters of two Pacific-basin rivers, the Chira and the Piura. On the eastern side the Huancabamba Deflection is notable, where there are major changes in the overall geology of the Andes (Sillitoe 1974; Feininger 1987) and the Marañón River turns eastward into the Amazon Basin.

Because of the complexity and the high number of species known only from the Huancabamba region, Duellman (1979) and Berry (1982) consider it separately from other Andean regions. The geological history and topography of the region have resulted in one of the most important barriers and filters affecting biotic migration in the Andes. For example, the Huancabamba Depression "probably accounts for a proportionately larger increase in the number of [bird] species than any other barrier along the Andes" (Vuilleumier 1969). Many northern or southern terminations of distributions are seen among species of rodents (Reig 1986), birds (Vuilleumier 1969, 1977; Vuilleumier and Simberloff 1980; Parker et al. 1985), reptiles and amphibians (Duellman 1979; Cannatella 1982; Cadle 1991; Duellman and Wild 1993), butterflies (Descimon 1986) and plants (Simpson 1975; Molau 1978, 1988; Baumann 1988).

The region also has served as an east-west corridor between the Amazon and Pacific basins (Gentry 1982; Cadle 1991; Patterson, Pacheco and Ashley 1992). In addition, isolation of the region's mountain ranges and inter-Andean valleys has promoted speciation - Panero (1992) includes a discussion of how speciation may have occurred in this and similar regions.

The region receives climatic and biogeographic influences from the Amazon Basin, the highlands of southern Ecuador and northern Peru, Pacific Ocean drainages and inter-Andean dry forests. Seasonal rains occur between December and March, and are exacerbated by the oceanic El Niño flow, which is associated with significantly more rainfall. The mean annual precipitation in non-El Niño years is 800-2500 mm. In areas above 2000 m elevation, high humidity is common due to the persistence of clouds during many months each year.

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There is great biological heterogeneity because the region is a major biogeographical crossroads, and each vegetation type is of limited extent. Dry forests and scrub occur at lower elevations and in the valleys. Areas above c. 1700 m are predominantly montane cloud forests. "Páramo" grasslands are found above the treeline, which is at 3200-3500 m.

Dry forest extends from the valleys to c. 1700 m, and is dominated by a scattered to dense cover of legume trees of Prosopis, Acacia, Piptadenia and Parkinsonia. Other characteristic genera include Capparis (Capparaceae), Cordia (Boraginaceae), Eriotheca (Bombacaceae), Loxopterygium (Anacardiaceae) and Muntingia (Tiliaceae). The herbaceous layer is dominated by species of Asteraceae, Fabaceae, Solanaceae and Poaceae.

Montane cloud forest is the major vegetation type and typically extends from 1700-3300 m. Clouds from the Amazon produce high humidity on the slopes of the Andes, creating a dense, epiphyte-laden forest, often 15-25 m high. Characteristic trees include Weinmannia (Cunoniaceae); Cassia (Fabaceae); Ocotea, Persea (Lauraceae); Miconia (Melastomataceae); Cedrela, Guarea, Ruagea, Schmardaea (Meliaceae); Myrsine (Myrsinaceae); Cinchona (Rubiaceae); Prunus, Hesperomeles (Rosaceae); Zanthoxylum (Rutaceae); Ficus, Morus (Moraceae); Cupania (Sapindaceae); and Solanum (Solanaceae). The epiphytes are mostly orchids and bromeliads.

Andean highland vegetation, often called "jalca" or páramo in this region (cf. CPD Site SA33), is a shrubby grassland occurring above the montane cloud forest, around 3200 m and higher. Species of Poaceae and Asteraceae dominate except in bogs, where species of Cyperaceae predominate.

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Based on the diversity of comparable regions in Ecuador and Peru, at least 2000-2500 species of vascular plants occur in this region. The evidence suggests that species-level endemism is quite high - the Huancabamba region (picture) has been identified as an Andean centre of endemism, despite the fact that the region is still insufficiently inventoried (Berry 1982). In addition, many Northern Andean species reach their southern distributional limit and many Central Andean species reach their northern limit. Data on floristic composition can be extracted or extrapolated from Weberbauer (1945), Valencia (1990), Cano and Valencia (1992), Gentry (1992), Jørgensen and Ulloa-Ulloa (1992) and Kessler (1992).

Dry forests have tree species such as Caesalpinia corymbosa, Capparis angulata, C. mollis and Eriotheca discolor, in addition to cereoid columnar cacti (Weberbauer 1945).

Important woody plant families in the humid montane forests include Araliaceae, Asteraceae, Clusiaceae, Cunoniaceae, Ericaceae, Euphorbiaceae, Lauraceae, Melastomataceae, Moraceae, Myrsinaceae, Myrtaceae, Rubiaceae and Solanaceae. Important genera of trees and shrubs include Ilex, Oreopanax, Schefflera, Baccharis, Diplostephium, Gynoxys, Berberis, Brunellia, Centropogon, Siphocampylos, Hedyosmum, Clethra, Clusia, Weinmannia, Vallea, Gaultheria, Vaccinium, Escallonia, Ocotea, Persea, Desfontainia, Gaiadendron, Brachyotum, Miconia, Myrica, Myrcianthes, Myrsine, Piper, Podocarpus, Prumnopitys, Monnina, Oreocallis, Hesperomeles, Palicourea, Cestrum, Solanum and Symplocos. Important genera of climbing and epiphytic plants include Bomarea, Anthurium, Mikania, Munnozia, Tillandsia, Coriaria, Fuchsia, Elleanthus, Epidendrum, Masdevallia, Odontoglossum, Oncidium, Pleurothallis, Telipogon, Oxalis, Passiflora, Peperomia, Muehlenbeckia and Calceolaria.

In the montane forest, other significant taxa include the rare Andean cedar Cedrela lilloi, two endemic species of Zanthoxylum, and Bignoniaceae endemics: Jacaranda sprucei (the highest-altitude species of the genus) and an undescribed Tabebuia species.

In the ecotone between the montane cloud forest and high-elevation zone, Asteraceae and Ericaceae become especially evident. Páramo species include grasses (Calamagrostis, Festuca); sedges (Carex, Oreobolus, Scirpus); composites (Baccharis, Bidens, Diplostephium, Hieracium, Senecio, Werneria); ericads (Befaria, Disterigma, Gaultheria); and scrophs (Bartsia, Calceolaria).

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Useful plants

Prance (1989) recognized "Podocarpus forest" in this region, because its mesic montane forests have important large populations of the podocarps Podocarpus oleifolius and Prumnopitys montana. These timber species are eagerly logged. They grow as large trees with numerous other tree species (e.g. Zevallos-Pollito 1988). Podocarpus sprucei is found in seasonally drier montane forests. Other timber species of high market value are also found in the region, including the rare "cedar" Cedrela lilloi and Schmardaea microphylla, a relative of mahogany (Swietenia) (Pennington et al. 1990).

Traditionally, the region has been a source of fuelwood and medicinal plants for local people. Many species of orchids and bromeliads have potential use as ornamentals.

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Social and environmental values

The most conspicuous value of the natural ecosystems is probably for water production. All the agricultural development projects of northern Peru and southern Ecuador depend on irrigation of the dry inter-Andean valleys and the arid coastal plain. Only by keeping the upper watersheds protected can these water sources be assured, for municipal drinking water and huge irrigation projects.

Extracted timber tends to leave few economic benefits for local inhabitants, because the forests are not managed sustainably and reforestation is generally not practised. The region's flora includes useful plants and wild relatives of crop species, many of which are not found elsewhere. In addition, the natural ecosystems provide necessary habitats for many animal species, including many endemic species.

Economic assessment

Approximately 400,000 people live in the Peruvian portion of the region and perhaps another 150,000 are in the Ecuadorian portion. All indications are that this region will become increasingly attractive for both government-sponsored and spontaneous colonization.

Following road building and concomitant timber extraction, land at low to middle elevations is put into production of agricultural products such as coffee, fruits, maize and rice, often with irrigation. Land at high elevations is used as a source of timber and fuelwood or is converted into cattle rangeland. Development planning for this region appears to have neglected or underestimated the economic value of intact forests as watershed protection for the water supply.

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The dry forests and semi-arid vegetation types are unique and unprotected. Probably all of them have been significantly altered by human activities.

The humid montane forests are the most threatened of this type of ecosystem in Peru; those of southern Ecuador appear to be already severely degraded. These forests are naturally isolated (Dillon 1994), and have been additionally fragmented by clearing for agriculture and rangeland. Perhaps 75% of the original humid forest has been removed and replaced by agricultural systems or scrub. The anthropogenic fragmentation is an ongoing process, but some fairly large tracts of forest are still continuous, especially in Peru near the border with Ecuador. In the past few years these forests have become increasingly threatened by logging for the valuable timber species.

Expansion of the agricultural frontier in both southern Ecuador and northern Peru continues to put great pressure on the remaining natural areas. A result is loss of habitat for animal and plant species. Gold mining also takes place in the region, and there are border disputes between the two countries.

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The Huancabamba region needs an expanded and improved park and nature reserve system. One nature reserve exists: the Tabaconas-Namballe National Sanctuary (295 km²) to the west of the town San Ignacio (Map 68), which was established in 1988 by the Peruvian Government. This potentially valuable conservation unit is unprotected and unstudied. In nearby regions, parks and reserves include: in Peru, Cutervo National Park near the town of that name (cf. Dillon 1994) and Noroeste Peruano Biosphere Reserve (see Data Sheet SA41); and in Ecuador, Podocarpus National Park between Loja and Zamora.

Existing laws concerning logging contracts, sale of timber products and reforestation require strong enforcement. National and international attention, plus funding, are needed to ensure that these laws and regulations are implemented. These forests are often used by local people, so conservation requires programmes that involve resource extraction and restoration projects. Local programmes of reforestation and watershed protection that include native tree species and management of the natural forests are needed. Vargas (1938) and Veillón (1962) have promoted the development of silvicultural practices for podocarps, but little has been done in Peru or Ecuador.

Also important are transnational biodiversity assessments and conservation strategies. For example, establishment of binational reserves or parks in this region could lead to an improvement in relations between the governments of Peru and Ecuador.

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Map 68. Huancabamba Region, Northern Peru and Southern Ecuador (CPD Site SA32)


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Cano, A. and Valencia, N. (1992). Composición florística de los bosques nublados secos de la vertiente occidental de los Andes peruanos. In Young, K.R. and Valencia, N. (eds), Biogeografía, ecología y conservación del bosque montano en el Perú. Memorias del Museo de Historia Natural, Vol. 21. Universidad Nacional Mayor de San Marcos (UNMSM), Lima. Pp. 171-180.

Clapperton, C.M. (1993). Quaternary geology and geomorphology of South America. Elsevier, Amsterdam. 779 pp.

Descimon, H. (1986). Origins of lepidopteran faunas in the high tropical Andes. In Vuilleumier, F. and Monasterio, M. (eds), High altitude tropical biogeography. Oxford University Press, New York. Pp. 500-532.

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Patterson, B.D., Pacheco, V. and Ashley, M.V. (1992). On the origins of the western slope region of endemism: systematics of fig-eating bats, genus Artibeus. In Young, K.R. and Valencia, N. (eds), Biogeografía, ecología y conservación del bosque montano en el Perú. Mem. Museo Hist. Nat., Vol. 21. UNMSM, Lima. Pp. 189-205.

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Valencia, N. (1990). Ecology of the forests on the western slopes of the Peruvian Andes. Ph.D. thesis. University of Aberdeen, Aberdeen, Scotland.

Vargas, C.C. (1938). El Podocarpus glomeratus Don (intimpa), y la silvicultura nacional. Acad. Cien. Exactas Físicas Nat. Lima (Perú) 1: 27-32.

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Zevallos-Pollito, P.A. (1988). Estudio dendrológico de las podocarpáceas y otras especies forestales de Jaén y San Ignacio. Consejo Nacional de Ciencia y Tecnología, Lima.


This Data Sheet was written by Dr Kenneth R. Young (University of Maryland Baltimore County, Department of Geography, Baltimore, MD 21228, U.S.A.) and Carlos Reynel (Universidad Nacional Agraria, Departamento de Biología, Secc. Botánica, Apartado 456, La Molina, Lima, Peru).

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