Location and General Description
The eastern Panamanian montane forests are located in the southeastern portion of Panama, in the Darién Province. Located in the highlands of eastern Panama, these montane forests occur from 500 m to approximately 1,800 m, where they grade into Paramo grasslands. Precipitation on the mountains ranges between 3,000 and 4,000 mm. In the Caribbean Coast the rainfall is higher - between 4,000 and 5,000 mm; in the central mountains it is lower, ranging from 1,700 to 2,800 mm (Herrera-MacBryde, 1997).
This southern portion of Central America is in a zone of plate convergence, where two small oceanic plates are being driven down below the Caribbean continental plate. This tectonic instability, combined with active volcanism, produced isolated volcanic islands between northern Central America and Colombia. The northeastern section of the ecoregion contains the Cordillera de San Blass and the Serranía del Darién, from which rises Cerro Tacarcuna (1,875 m), the highest mountain between the Andes and western Panama. The southern section encompasses discontinuous mountain chains including the Serrania de Jungurudó, Serranía de Bagre, and Serranía del Sapo, which borders the Pacific Ocean (Herrera-MacBryde, 1997).
The ecoregion includes various vegetation types, including marshes and swamp forests, semi-deciduous tropical moist forests, premontane wet forest, cloud forests and elfin forests. The last two are found at low elevations due to the isthmian effect. Semi-deciduous tropical moist forest are the most widespread; they include canopy trees such as Bombacopsis quinata, B. sessilis, Enterolobium cyclocarpum, Licania hypoleuca, Pltypodium elegans, Pseudobombax septenatum, Sterculia apelata, Terminalia amazonica, Tetragastris panamensis and Vitex cymosa. The premontane and montane wet forests contain Anacardium excelsum as the dominant canopy tree. Other common canopy species include Bombacopsis spp., Brosimum guianense, Ceiba pentandra, Cochlospermum williamsii, Dipteryx panamensis, and Myroxylon balsamum. (Herrera-MacBryde, 1997). The dominant subcanopy tree is Oenocarpus panamanus, and Mabea occidentalis is the dominant understorey shrub. Cloud forest can be seen above 750 m, with Oenocarpus panamanus as the dominant species. Elfin forests are found at the highest elevations, containing the predominant Clusia spp. (Gentry 1985).
This ecoregion's combination of significant elevational changes, climatic variations, and location on the land bridge between North and South America, provide it with tremendous biological diversity and endemism (Delgado 1985, Méndez 1994). The lush, dense montane forest shares biological affinities with neighboring Colombia (Delgado 1985).
This land bridge region between North and South America has allowed the mix of northern and southern species and encouraged the rise of endemic species- thus, the approximately 770 vertebrate species in the Darien Province. Among the mammals are six primates and five felids. The primates include the western night monkey (Aoutis lemurinus), Central American spider monkey (Ateles geoffroyi) , brown-headed spider monkey (Ateles fuscipes), Geoffroy’s tamarin (Saguinus geoffroyi.), mantled howler monkey (Alouatta palliata) and white-faced capuchin (Cebus capucinus) (Herrera-MacBryde 1997). Geoffroy's tamarin is found only in southern Costa Rica, Panama, and northwestern Colombia. The cats species are puma, jaguar (Felis onca), ocelot (Leopardus pardalis), margay (Leopardus wiedii), jaguarundi (Herpailurus yaguarondi) and oncilla (Felis tigrina). This ecoregion represents range limits for many species, such as the night monkey (Aotus spp.) who doesn’t oocur north of this region (Emmons 1990), and of many birds which have wider distributions in South America, including the saffron-headed parrot (Pionopsitta pyrilia), oilbird (Steatornis caripensis), and golden-headed Quetzal (Pharomacrus auriceps). Endemic herpetofauna in the ecoregion includes two snakes, a lizard, a salamander and five frogs (Herrera-MacBryde, 1997).
The endemic birds in this ecoregion are also present in the Choco/Darién Moist forest ecoregion. All of the restricted-range birds are found at elevations ranging from 700-800 m, and none are considered threatened; such birds include the Tacarcuna wood-quail (Odontophorus dialeucos), russet-crowned quail-dove (Geotrygon goldmani), bare-shanked screech-owl (Otus clarkii), violet-capped hummingbird (Goldmania violiceps), rufous-cheeked hummingbird (Goethalsia bella), beautiful teerunner (Margarornis bellulus), tacarcuna tapaculo (Scytalopus panamensis), nario tapaculo (S. vicinor), varied solitaire (Myadestes coloratus), sooty-faced finch (Lysurus creassirostris), tacarcuna bush-tanager (Chlorospingus tacarcunae), pirre bush-tanager (Bangsia arcaei), yellow-collared chlorphonia (Chlorophonia flavirostris), green-napped tanager (Tangara fucosa) and pirre warbler (Basileuterus ignotus) (Stattersfield et al. 1998).
Steep slopes, and limited accessibility have prevented widespread agricultural and urban development, and have contributed to the existence of large, intact blocks of habitat which still remain in these highlands. But new roads and other public infrastructure have brought colonists from central Panama who are cutting the forest rapidly.
Much of the ecoregion is protected mainly by Parque Nacional Darién (5,790 km2), a World Heritage Site and Central America's largest national park, which protects 575,000 ha (Méndez 1994). This Park harbors 13 endangered amphibians and 11 endangered reptiles (Young et al 1999). Other protected areas in the ecoregion include Indigenous Reserves such as the Kuna de Walá Mortí and Nurrá; the Canglon Forest Reserve with 316 km2 ; Chepigana Forest Reserve with 1,460 km2; and the Choco homelands Comarca Emberá No. 1 with 1,826 km2.
Types and Severity of Threats
The construction of the Pan-American highway through this region has caused rapid colonization from central Panama and subsequent intensive deforestation. Forest on the foothills and hilltops will likely be the last portions eliminated, but will be isolated by the fragmentation associated with lowland deforestation. Extending the Pan-American highway into Colombia will exacerbate deforestation by facilitating access to the forests to poor Colombian immigrants (Delgado 1985). Even where protection of these montane forests is enforced, the increasing destruction of middle and lower elevation habitats in surrounding ecoregions has isolated the highland forests and made their populations vulnerable to genetic degradation. Cloud forests are particularly sensitive to climate change. Traditional indigenous uses have maintained substantial forest cover, but recent socio-economic pressures from the extension of the Pan American highway, forestry exploitation, and selling of illegally-caught wildlife, such as macaws, parrots, and passerine birds, is changing their ancestral attitudes toward nature (Delgado 1985).
The biodiversity in these parks are threatened by the instability produced from the deterioration of government infrastructure, including parks, under pressures caused by drug-related and other violence in Colombia (Powell pers. comm.). Delgado (1985) described the enforcement of conservation measures in eastern Panamanian parks as ineffective. Protection is afforded to Llorona San Blas's Ridge, located in the Kuna Indian Reserve of San Blas; these highlands have maintained forest cover due to the Kuna's jealous guarding of their natural resources (Delgado 1985).
Justification of Ecoregion Delineation
These montane forests were delineated following the UNDP (1970) vegetation map, and to a lesser degree the Navarro et al (1984) map along the border region between Panama and Colombia. This ecoregion encompasses the Serrania de Pirre, Serranía de Jungurudó, Serranía de Majé, Altos de Limos, Altos de Puna, Altos de Aspavé, and Altos de Quía regions of the Panama-Colombia border region following UNDP (1970) classifications of montane and lower montane wet and rain forests. These isolated ranges and peaks have distinct flora and fauna from the surrounding lowlands, some endemic species, and are a convergence zone for Central American montane forests and Andean montane forests species assemblages.
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Prepared by: George Powell, Sue Palminteri, and Jan Schipper
Reviewed by: In process