Included here are the forests of the Magdalena Valley, Panama Canal, Panama's Darién province, and the Choco region of western Colombia and Ecuador.

Chocóan Upland Rainforest (Bajo Calima)

These forests occur on low hills composed of Tertiary sediments. The soils are very low in nutrients and possibly have the lowest phosphorus levels of any known Neotropical forest. At canopy level the palm Jessenia batava appears to be the most common species, but other palms such as Socratea exorrhiza and species of Wettinia are also common and, in fact, these forests appear to support more palm species than any other part of the World. Other dominant canopy trees include Eschweilera panamensis (Lecythidaceae), Manilkara bidentata (Sapotaceae) and Otoba lehmannii (Myristicaceae), while other important trees are Brosimum utile (Moraceae), Miconia punctata (Melastomataceae), Micropholis crotonoides (Sapotaceae), Pouteria buenaventurensis (Sapotaceae), Tovomita weddelliana (Clusiaceae), Welfia georgii (Arecaceae) and Wettinia quinaria (Arecaceae). However, the overstory or canopy of these forests is extremely rich with up to 258 species recorded in just one hectare. Important families in terms of species-richness include Annonaceae, Arecaceae, Hypericaceae, Fabaceae, Melastromataceae, Rubiaceae and Sapotaceae. These forests are also especially important for the family Burseraceae in terms of species-richness, endemism and ecological dominance, and for the prevalence of Bombacaceae especially the genus Quararibea. In fact, trans-Andean forests appear to be the centre of diversity for this genus. The under storey is variable but typically includes Mabea occidentalis (Euphorbiaceae), Macrolobium archerii (Fabaceae), Miconia centronoides (Melastomataceae), Pausandra trianae (Euphorbiaceae), and Tetrorchidium ochroleucum (Euphorbiaceae), and can, in fact, support up to three times as many trees as the over storey. The most important shrub families are Melostomataceae, Piperaceae, Rubiaceae and Solanaceae. There is a very high diversity of climbers although most of these are hemi epiphytes, including species of Cavandisha, Clusia, Drymonia, Ficus, Marcgravia, Norantea, Schradera and Topobea, rather than free-climbing lianas. Normal epiphytes are also well represented particularly by the Araceae, but also include many bromeliads, cycanths, gesneriads, orchids, and peperomias. Among the terrestrial herbs Acanthaceae, Commelinaceae and Gesneriaceae are well represented.

Tumbesian Low Montane Cloud Forest

Situated on the lower seaward slopes at altitudes ranging from 500-1500 m these forests are constantly subject to very humid conditions because of condensation from frequent cloud cover and is little affected by the dry season. In the Buenaventura area these often open canopy forests can reach heights of 35 m and have emergents extending up to 45 m. Depending on location some of the characteristic tree species include Centrolobium paraense, Podandrogyne brevipedunculata, Matisia cordata, Ochroma pyramidale, Mabea occidentalis, Muntingia calabra, Rheedia edulis, Symphonia globulifera, Spondias purpurea, Tabebuia guayacan, Vemonia baccharoides, Banara guianensis, Conostegia cuatrecasii, Ossaea boeckii, Cedrela odorata, Ficus gigantorice, Myrica pubescens, Bocconia integrifolia, Coccoloba obovata, Oreocalyx grandiflora, Turpinia occidentalis, Heliocarpus americanus, Urera caracasana and various species of Miconia. The open conditions allow sufficient sub canopy light for dense middle and under storey formations, and as expected the epiphytic flora is well developed. In fact, dense mats of epiphytes cover much of the canopy branches. These include numerous lichens, bryophytes, ferns, orchids, and species of Araceae and bromeliads. The latter include a large number of Guzmania species such as G. angustifolia, G. garciaensis and G. hitchcockiana which here are much more prevalent than Tillandsia species which tend to be more numerous in less humid conditions. The few species included T. acosta-solisii, T. narthecioides, T. pseudotetrantha and T. venusta.

Darien Premontane Wet Forest

Located largely in the San Blas cordillera at elevations ranging from 250-600 m these forests characteristically have a dense, evenly closed canopy with many sub canopy palms. The canopy rarely exceeds 30 m and most of the trees are relatively slender although many have buttress or stilt roots. Among the most abundant canopy trees are Anacardium excelsum, Bombacopsis quinata, B. sessilis, Brosimum quianense, Ceiba pentandra, Myroxylon balsamum and Oleiocarpon panamense while listed among the less common species are various Panamanian endemics such as Couroupita magnifica, Lecythis tuyrana, L. elata (Lecythidaceae), Mimusops dariensis (Sapotaceae) and Platymisicum dariense (Fabaceae). A number of canopy species are draught deciduous. The sub canopy is relatively open and in addition to many palms also includes numerous other trees and tree ferns. Some of the most common are Brownia rosa-de-monte, Cespedesia macrophylla, Chomelia spinosa, Conostegia xalapensis, Gustavia superba, Heisteria longipes, Iriartea cornata, Luechea seemannii, Miconia borealis, Oenocarpus panamanus, Ouratea lucens, Pentagonia macrophylla, Pogonopus speciosus, Posoqueria latifolia, Pourouma scabina, Siparuna pauciflora, Stemmadenia grandiflora, Warszewiczia coccinea and Xylopia frutescens. The subcanopy also include a number of Panamanian endemics such as Cecropia longipes (Moraceae), Ceiba rosea (Bombacaceae), Gloeospermum portobellensis (Violaceae), Guapira standleyiana (Nyctaginaceae), Guatteria panamensis (Fabaceae), Inga saffordiana (Fabaceae), Macrolobium pittieri (Ochnaceae), Eschweilera panamensis (Lecythidaceae) and Pentagonia brachyotis (Rubiaceae). The dense canopy allows little light to penetrate and so the under storey tends to be fairy open. Nevertheless there are a number of terrestrial herbs. The most abundant of these are Aphelandra sindairiana, Clavija mezii, Clidemia dentata, Coccoloba coronata, Conostegia bracteata, Faramea luteovirens, Hasseltia floribunda, Henrietella fascicularis, Herrania purpurea, Leandra dichotoma, Mabea occidentalis, Palicourea guinensis, Picramnia antidesma, Pothomorphe petata, Psychotria involucrata and a variety of Miconia, Piper and Psychotria species. Several Panamanian endemics also occur including Coccoloba manzanillensis (Polygonaceae), Mollinedia darienensis (Monimiaceae), Piper lucigaudens (Piperaceae) and Topobea pluvialis (Melastomataceae). Lianas, vines and epiphytes are also common. Two of the most abundant woody vines are Drymonia spectabilis and Passiflora vitifolia while some of the less common include Strychnos dariensis (Loganiaceae), which is probably endemic to Panama. Herbaceous vines seem less frequent but include the Panamanian endemic Clidemia oblonga (melastomataceae). Epiphytes are mostly found in the canopy or on the boles of trees and typically include Begonia guaduensis, Columnea consanguinea, Drymonia serrulata, Epidendrum crassilabium, Guzmania minor, Monstera adansonii, Philodendron piperoides, Sphyrospermum buxifolium, Tillandsia crispa and a variety of Anthurium species. At ground level the most abundant herbs include Coccocypselum herbaceum and Spigelia anthelmia while among the less common species are the Panamanian endemics Begonia garagarana (Begoniaceae) and Peperomia urocarpoides (Piperaceae). 

Magdalena Montane Forest

Situated on the inner slopes of the Eastern and Central cordilleras above the Magdalena River these wet forests are often enveloped in cloud and at elevations above 1800 m could be described as cloud forest. The most important trees are Anacardium excelsum, Aniba perutilis, Cedrela odorata, Cordia alliodora, Decussocarpus rospigliossi, Podocarpus oleifolius, Quercus humboldtii, Tabebuia rosea and Vochysia ferruginea. Palms are also an important feature with species such as Ceroxylon alpinum, C. parvifrons, C. quindivense, C. vogelianum, Dictyocaryum lamarckianum and the local endemic species Ceroxylon sasaimae (Arecaceae). Other local endemics include Odontoglossum crispum (Orchidaceae) and various heliconias such as Heliconia abaloi, H. estiletioides, H. huilensis, H. laxa, H. mutisiana, H. oleosa and H. reptans (Heliconiaceae).

References

Anon. 1996. Habitats of South America. Institute of Terrestrial Ecology and Intitut Royal Des Sciences Naturelles De Belgique.

Best, B. J. & Kessler, M. 1995. Biodiversity and Conservation in Tumbesian Ecuador and Peru. BirdLife International.

Faber-Langendoen, D. & Gentry, A. H. 1991. The structure and diversity of rain forest at Bajo Calima, Chocó region, western Colombia. Biotropica, 23: 2-11.

Galeano, G., Suárez, S. & Balslev, H. 1998. Vascular plant species count in the wet forest in the Chocó area on the Pacific coast of Colombia. Biodiversity and Conservation, 7: 1563-1575.

Gentry, A. H. 1982. Phytogeographic Patterns as Evidence for a Chocó Refuge. In: Biological Diversity in the Tropic. Ed. G. T. Prance. Columbia University Press.

Gentry, A. H. 1986. Species richness and floristic composition of Chocó region plant communities. Caldesia, 15: 71-79.

Grubb, P. J., Lloyd, J. R., Pennington, T. D. & Whitmore, T. C. 1963. A comparison of montane and lowland rain forest in Ecuador. Journal of Ecology, 51: 567-601.

Harling. G. 1979. The vegetation types of Ecuador a brief survey. In: Tropical Botany. Eds. K. Larsen and L. B. Holm-Nielsen. Academic Press.

Lamb, F. B. 1953. The forest of Darien, Panama. Caribbean Forester, 14: 128-153.

Porter, D. M. 1973. The vegetation of Panama: a review. In: Vegetation and vegetational history of northern Latin America. Elsevier Scientific Publishing Company.

Prance, G. T. 1982. Forest Refuges: Evidence from Woody Angiosperms. In: Biological Diversity in the Tropic. Ed. G. T. Prance. Columbia University Press.

Sarker, S., Sánchez-Cordero, V., Londoño, M. C. & Fuller, T. 2009. Systematic conservation assessments for the Mesoamerica Chocó, and Tropical Andes biodiversity hotspots: a preliminary analysis. Biodiversity and Conservation, 18: 1793-1828.

Silverstone-Sopkin, P. A. & Ramos-Pérez, J. E. 1995. Floristic exploration and phytogeography of the Cerro del Torrá, Chocó, Colombia. In: Biodiversity and Conservation of Neotropical Montane Forests. Eds. S. P. Churchill, H. Balslev, E. Forero and J. L. Luteyn. The New York Botanical Garden.

Standley, P. C. 1928. Flora of the Panama Canal zone. Smithsonian Institution United States of America. Contributions from the United States National Herbarium. Volume 27.

Svenson, H. K. 1946. Vegetation of the coast of Ecuador and Peru and its relationship to the Galapagos Islands. I. Geographical relations of the flora. American Journal of Botany, 33: 394-426.

Valencia, R., Balslev, H., Palacios, W., Neill, D., Josse, C., Tirada, M. & Skov, F. 1998. Diversity and family composition of trees in different regions of Ecuador: a sample of 18 one-hectare plots. In: Forest biodiversity in North, Central and South America and the Caribbean. Eds. F. Dallmeier and J. A. Comiskey. Man and the Biosphere Series, Vol. 21. The Parthenon Publishing Group.

Weigend, M., Rodrígues, E. F. & Arana, C. 2005. The relict forests of northwest Peru and southwest Ecuador. Revista Peruana de Biología, 12: 185-194.

Werff, H. Van Der. & Consiglio, T. 2004. Distribution and conservation significance of endemic species of flowering plants in Peru. Biodiversity and Conservation, 13: 1699-1713.