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CERRO AZUL-CERRO JEFE
The Cerro Azul-Cerro Jefe region (Map 30) is in the Province of Panama c. 52 km north-east of the capital (Panama City). The region is located in the Cordillera de San Blas; Cerro Azul reaches 691 m, Cerro Jefe 1007 m. The topography is uneven, with ravines of varying depth.
The Cerro Azul-Cerro Jefe uplift is on the continental divide and the source of rivers flowing to both oceans on the Pacific slope, including the Pacora, Tocumen and Juan Díaz rivers; on the Caribbean slope, including several rivers of the Chagres watershed which supplies major reservoirs. Gatún Lake (423 km²) was formed by damming the Chagres River in 1910 during construction of the Panama Canal and is an integral part of the watercourse for the transit of ships; Alajuela (Madden) Lake (57 km²) was formed in 1936.
Geologically, Cerro Azul and possibly Cerro Jefe are part of the Cerro Azul pluton. Comparison of magmatic rocks shows similarities between the plutons of cerros Azuero and Azul and the Pito (Darién) River (Destro 1986). This supports Recchi's hypothesis on the geological evolution of Panama, that the Azuero Peninsula and the area spreading out from Cerro Azul to the Pito River were aligned in pre-Tertiary and Palaeocene eras, and the pluton outcropped there, having arisen from a common magma. Later tectonic plate action moved the plutonic block northward that has become Cerro Azul and adjacent areas.
In nearby regions, there are various geologic faults due to past volcanic and tectonic activity. One of these faults is along the course of the Chagres River, interrupted upstream by the volcanic crater in Alajuela Lake.
According to the geologic map of Panama (IGN 1988), the bedrock of Cerro Azul is igneous-extrusive, including basalt, andesite, tuff and ignimbrite, whereas the bedrock of Cerro Jefe and its boundary areas is igneous-intrusive, including granodiorite, quartz-monzonite and diorites.
The soils are moderately to very stony latosols, and acid to very acid; they are non-arable (class VII), suitable only for forests and reserves. On the Cerro Jefe summit the considerably different concentrations of elements found in the soils have been sampled - especially iron, potassium and manganese (Valdespino 1988). There are acidic Sphagnum peat bogs, mainly on Cerro Jefe.
The forest is frequently foggy as a result of the climatic conditions that characterize this region. Winds from the north and north-east loaded with moisture from the Caribbean Sea prevail, resulting in an annual average rainfall of nearly 4000 mm (Valdespino 1988). The temperature during the year ranges between 17°C and 26°C.
This region includes three life zones in the Holdridge system: tropical premontane wet forest, tropical wet forest and tropical premontane rain forest (Tosi 1971).
In the tropical premontane wet-forest zone at c. 300-500 m, as a result of many years of human activities, generally the more or less fallow vegetation is mostly herbaceous. Saccharum spontaneum, an aggressive introduced herb to 3 m tall, has extended widely and partially displaced fodder pastures of the African grasses Hyparrhenia rufa and Panicum maximum, as well as native plants.
There are occurrences of shrubs if Saccharum spontaneum is absent, e.g. species of Dilleniaceae, Melastomataceae and Compositae, and sun-loving trees such as Apeiba tibourbou, Xylopia aromatica, X. frutescens, Anacardium occidentale, Cecropia sp., Vismia sp. and Cordia alliodora.
In disturbed older secondary vegetation occur trees such as Enterolobium schomburgkii, Didymopanax morototonii, Spondias mombin, Pseudobombax septenatum and Calycophyllum candidissimum. On degraded soils predominate Roupala montana and some species of Clusia and Melastomataceae.
At 600-800 m mature forest is found, interrupted by areas converted by the poultry-breeding industry, settlement and coffee cultivation. In this forest there are several arboreal strata and emergents 30 m or more tall, including Calophyllum longifolium, Pouteria sp., Podocarpus cf. oleifolius and the palms Welfia georgii, Socratea durissima (S. exorrhiza), Euterpe precatoria and Wettinia augusta (picture).
The diversity of epiphytes is high, including for example bryophytes (liverworts and mosses), lichens, ferns, Bromeliaceae, Orchidaceae, Araceae, Cyclanthaceae and Ericaceae.
Toward the Caribbean slope mature forest is relatively better preserved, both tropical wet forest and tropical premontane rain forest, due partly to the rough topography and the abundant precipitation. Nonetheless, there is an area near Cerro Jefe known as Cerro Pelón where the vegetation is almost totally herbaceous, with Rhynchospora cephalote predominant, accompanied by species such as Trachypogon plumosus, Andropogon bicornis, A. leucostachys and Scleria sp. Occasionally the palm Colpothrinax cookii is found.
The forest on the summit of Cerro Jefe (pictures) is influenced by frequent strong winds, having a vegetation of shrubby trees, generally 8-15 m tall with medium-sized to small leathery leaves; it shows a tendency towards sclerophylly (Gentry 1982). In this type of forest flourish Ardisia sp., Alchornea sp., Myrsine sp., Clusia spp. and some Sapotaceae, and endemics such as Psychotria olgae, Licania jefensis and Vismia jefensis (picture). Epiphytic plants are abundant - Orchidaceae and Bromeliaceae are most representative (Torres 1989). At the leaf bases of Vriesea sp., Guzmania sp. (pictures) and other bromeliads that retain water it is easy to find Utricularia jamesoniana, a carnivorous plant that feeds on organisms in the accumulated solutions.
Colpothrinax cookii (picture) (Read 1969) is prominent because of its dense populations; it is distributed up to 800 m. In primary forests with emergents it is infrequent or absent, and instead occur Socratea durissima (S. exorrhiza), Wettinia augusta and Euterpe precatoria - which tend to be shorter and stouter on hillsides and on the summit of Cerro Jefe. Olyra standleyi is sometimes concentrated in pure populations in open and disturbed areas.
Of the 1230 species endemic to Panama, 143 have been found on Cerro Jefe - including 45 local endemics (pictures). The angiosperm families with the highest number of endemic species are Rubiaceae (25), Araceae (13), Gesneriaceae (12), Ericaceae (picture) (8), Myrsinaceae (8), Compositae (picture) (7), Solanaceae (7) and Orchidaceae (5). Among the characteristic genera are Psychotria (picture) (16), Anthurium (13), Columnea (7) and (4) (Carrasquilla 1987).
Lewis (1971) concluded that the Cerro Azul-Cerro Jefe region, like other relatively high regions in Panama, has been a site of refuge and evolution for many taxa that were geologically isolated from the North American range of mountains which reaches western Panama. The flora of western Panama is more allied with the flora to its north-west, because of the continental connection by the Middle Miocene that united Central America and North America. At that time the flora of present eastern Panama was still on groups of low volcanic islands, which included Cerro Jefe, and which were populated by long-distance dispersal from nearby South America, as well as continental Panama. The Panamanian land-bridge between North America and South America became established c. 3.5-2.4 million years ago during the Late Pliocene (Graham 1972, 1985, 1993; Gentry 1982, 1985; Rich and Rich 1983).
Study of the flora of Cerro Azul-Cerro Jefe was initiated by P.H. Allen in the mid 1940s (Dwyer 1967); especially from 1965 onward, other foreign and Panamanian specialists have contributed much to the knowledge of the regional flora (cf. Martínez 1977-1978; Dwyer 1985; Hampshire 1989; Aranda 1991). Altogether, 836 species of flowering plants are recorded for Cerro Azul-Cerro Jefe. According to Carrasquilla (1987), on Cerro Jefe c. 486 species have been collected, 119 of which are epiphytes (pictures) (cf. Torres 1989).
The pteridophytes on Cerro Azul-Cerro Jefe are frequent and quite diverse - 98 species have been identified. On Cerro Jefe most of the species are in Polypodiaceae (14), Hymenophyllaceae (10), Dryopteridaceae (6), Gleicheniaceae (5) and Cyatheaceae (4), and in the genera Grammitis, Trichomanes and Elaphoglossum. Tree ferns are distinctive components of the Cerro Jefe forests - Trichipteris williamsii is most abundant, then Cyathea sp. (Valdespino 1988).
Among the disjunct species on Cerro Azul-Cerro Jefe, Hymenophyllum apiculatum is also known from Venezuela (e.g. Guayana Highlands) and Colombia (Meta and Valle), so the population in Panama probably resulted from long-distance dispersal. Licania affinis also has been recorded in the Guiana area. A number of species seem to be disjuncts from the Guayana region and especially the Guayana Highlands, probably representing pre-Andean survivors of the flora of the pre-isthmian uplifted islands (Gentry 1985). This insular past also may be indicated by several species shared with the isolated Cerro Tacarcuna (1900 m) bordering Colombia: Eleagnia nitidifolia, Conomorpha gentryi, Columnea mira and Vochysia jefensis. Grammitis randallii is another disjunct fern (also on Cerro Tacarcuna), which is also rare in Jamaica (D.B. Lellinger, pers. comm.). Colpothrinax cookii, which in recent years has been found in San Blas and Chiriquí, occurs as well in certain areas of Guatemala (Gentry 1982).
Of the c. 486 flowering plant species documented on Cerro Jefe, 101 extend in distribution only to Costa Rica and Colombia. Slightly more of the species extend from just Costa Rica or Panama to South America than from Mexico to South America (Carrasquilla 1987). As an example of the greater southern affiliation, five species of Miconia are shared between Panama and South America, but only one species is shared with Central America.
The floristic affinities on Cerro Jefe partly reflect the relative likelihood of phytogeographic opportunities from the neighbouring regions. South America is much larger and more diverse than Central America, and the pre-isthmian islands were more or less to the west of South America - receiving the westward-prevailing air currents of the Intertropical Convergence Zone and oceanic current. Thus the greater dispersal of plant propagules was from east to west.
Because this region is within Chagres National Park, exploitation of the native plants is infrequent and local. There are timber trees such as Calophyllum longifolium ("María"), Manilkara sp. ("níspero") and Podocarpus cf. oleifolius ("pino demontaña"). Occasionally, the leaves and stalks of Socratea durissima (S. exorrhiza) and Colpothrinax cookii ("palma escoba") are used to make huts. Uses of the endemic plants are unknown. Some species, e.g. in Rauvolfia, Cephaelis and Hamelia, have been investigated for their chemical and pharmacological properties.
Social and environmental values
The region has great environmental value because its vegetation helps to maintain the climate. The cerros are also the sources of several rivers that flow into the Chagres River watershed, which mainly provides Alajuela Lake with water. Forty percent of this water is used for the Panama Canal, the generation of hydroelectric energy, and the water supplies to Panama City and Colón.
Because of the region's climatic and topographic conditions, farming and animal husbandry practices are naturally somewhat restricted. Telecommunication installations have been established on the summits of Cerro Azul and Cerro Jefe.
The Cerro Azul-Cerro Jefe region includes private lands, primarily owned by one family. Only 9 km² of the private lands are used for settlement and avicultural projects; the remainder is reserved for scientific purposes and ecotourism - such as "El Cantar" trail on Cerro Azul, which attracts national and foreign tourists, who are amazed by the biological diversity and as well by the priceless beautiful scenery of the surrounding area.
These cerros are at the western end of two Endemic Bird Areas (EBAs A19 and A20) primarily centred on Darién Province (CPD Site MA20). Perhaps ten restricted-range species are known from the vicinity of these two mountains. The lowlands of Cerro Azul and Cerro Jefe may be most important for the threatened speckled antshrike (Xenornis setifrons).
There are sometimes fires, both accidental and intentional, which usually result from traditional agricultural practices (D'Arcy and Correa-A. 1985). Agro-industrial activities also create disturbances in the Cerro Azul-Cerro Jefe region. Portions of the Cerro Jefe cloud forest have been cut for grazing (picture) (Hampshire 1989).
Erosional sites have resulted in the deforested and settled areas following the abundant rains, causing sediment deposition in several rivers that flow into Lake Alajuela. Residents are undertaking reforestation with Pinus caribaea and on a smaller scale Araucaria sp. to reduce the erosion. The Cerro Azul-Cerro Jefe forests, in addition to protecting some of the Chagres watershed, also contribute to diminishing the risk of floods from these cerros' rivers that flow southward into Panama Bay.
For the protection of the Panama Canal and Lake Alajuela, creation of Chagres National Park (1290 km²) in 1984 was considered absolutely essential; it included Cerro Azul and Cerro Jefe. All the forests and lands were included that are profitable for water production and sustaining the Chagres watershed, which is one of the most important rivers for the national economy.
Preservation of this region is essential because of its high level of plant endemism, and its general biodiversity, including a wealth of animals such as Ramphastos, bats (Gallardo and Jiménez 1990), Alouatta, Saguinus and Bradypus. A range of biological studies has been carried out and future projects are being considered, in this way providing better knowledge of the kinds, quantity and quality of the wild life that through millennia has survived and developed in this unusual region of Panama. A management plan for the park has been prepared (INRENARE 1987).
Map 30. Cerro Azul-Cerro Jefe Region, Panama (CPD Site MA19)
Aranda, J.E. (1991). Estudio florístico de angiospermas terrestres en dos cuadrantes en Cerro Jefe, conjuntamente con una revisión del herbario y la Flora de Panamá para el mismo área. Universidad de Panamá, Departamento de Botánica, Panama City. 302 pp.
Carrasquilla, L.G. (1987). Características de la flora de angiospermas de Cerro Jefe, Provincia de Panamá. Universidad de Panamá, Departamento de Botánica, Panama City. 28 pp.
D'Arcy, W.G. and Correa-A., M.D. (eds) (1985). The botany and natural history of Panama: la botánica e historia natural de Panamá. Monogr. Syst. Bot. No. 10, Missouri Botanical Garden, St. Louis. 455 pp.
Destro de, T. (1986). El plutón de Cerro Azul. Boletín Informativo de la Facultad de Ingeniería Civil No. 10, Universidad Tecnológica de Panamá, Panama City.
Dwyer, J.D. (1967). A new herbarium in the Canal Zone. Taxon 16: 158-159.
Dwyer, J.D. (1985). The history of plant collecting in Panama. In D'Arcy, W.G. and Correa-A., M.D. (eds), The botany and natural history of Panama. Monogr. Syst. Bot. Missouri Bot. Gard. 10. Pp. 179-183.
Gallardo, M. and Jiménez, Z. (1990). Estudio de mamíferos del Chiroptera en un bosque secundario de cantera (sector de Alajuela), Parque Nacional Chagres. Universidad de Panamá, Escuela de Biología, Panama City. 32 pp.
Gentry, A.H. (1982). Phytogeographic patterns as evidence for a Chocó refugium. In Prance, G.T. (ed.), Biological diversification in the tropics. Columbia University Press, New York. Pp. 112-136.
Gentry, A.H. (1985). Contrasting phytogeographic patterns of upland and lowland Panamanian plants. In D'Arcy, W.G. and Correa-A., M.D. (eds), The botany and natural history of Panama. Monogr. Syst. Bot. Missouri Bot. Gard. 10. Pp. 147-160.
Graham, A. (1972). Some aspects of Tertiary vegetational history about the Caribbean Basin. In Memorias de Simposia, I Congreso Latinoamericano, V Mexicano de Botánica, Mexico, D.F. Pp. 97-117.
Graham, A. (1985). Vegetational paleohistory studies in Panama and adjacent Central America. In D'Arcy, W.G. and Correa-A., M.D. (eds), The botany and natural history of Panama. Monogr. Syst. Bot. Missouri Bot. Gard. 10. Pp. 161-176.
Graham, A. (1993). Historical factors and biological diversity in Mexico. In Ramamoorthy, T.P., Bye, R., Lot, A. and Fa, J.E. (eds), Biological diversity of Mexico: origins and distribution. Oxford University Press, New York. Pp. 109-127.
Hampshire, R.J. (1989). Panama. In Campbell, D.G. and Hammond, H.D. (eds), Floristic inventory of tropical countries: the status of plant systematics, collections, and vegetation, plus recommendations for the future. New York Botanical Garden, Bronx. Pp. 309-312.
IGN (Instituto Geográfico Nacional "Tomy Guardia") (1988). Atlas nacional de la República de Panamá. Panama City, Panama.
INRENARE (1987). Plan de manejo y desarrollo del Parque Nacional Chagres. INRENARE, Departamento de Parques Nacionales y Vida Silvestre, Panama City.
Lewis, W.H. (1971). High floristic endemism in low cloud forests of Panama. Biotropica 3: 78-80.
Martínez, A. (1977-1978). Estudio florístico en Cerro Jefe, Panamá. Universidad de Panamá, Departamento de Botánica, Panama City. 69 pp.
Read, R.W. (1969). Colpothrinax cookii a new species from Central America. Principes 13: 13-22.
Rich, P.V. and Rich, T.H. (1983). The Central American dispersal route: biotic history and paleogeography. In Janzen, D.H. (ed.), Costa Rican natural history. University Chicago Press, Chicago. Pp. 12-34.
Torres, N. (1989). Estudio sistemático de las especies de epífitas vasculares de Cerro Jefe, Provincia de Panamá. Universidad de Panamá, Departamento de Botánica, Panama City. 93 pp.
Tosi, J.A., Jr. (1971). Zonas de vida: una base ecológica para investigaciones silvícolas e inventariación forestal en la República de Panamá. FAO, Rome.
Valdespino, I.A. (1988). Estudio florístico de helechos en dos cuadrantes de Cerro Jefe, Provincia de Panamá. Universidad de Panamá, Departamento de Botánica, Panama City. 130 pp.
This Data Sheet was written by Prof. Luis G. Carrasquilla (Universidad de Panamá,
Escuela de Biología, Departamento de Botánica, Estafeta Universitaria, Panama City,
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