Catatumbo moist forests
The Catatumbo moist forests are among the richest in floral diversity in humid tropical areas of Venezuela. These forests flank the lower slopes and lowlands between the Cordillera de Mérida and the Cordillera Oriental of the northern Andes, and occur as several outliers in the vicinity of Lake Maracaibo.
Location and General Description
The Catatumbo moist forests exist as four distinct enclaves within the Catatumbo Valley, in both northwestern Venezuela and northeastern Colombia. In Venezuela the ecoregion is found in the states of Zulia and, and Lara, and in Colombia it is found in the Norte de Santander department. The forests are primarily lowland and premontane formations, and exist within a matrix of xeric and montane habitats. The largest, or "core" block, spans the premontane and inter-Andean valley region in a "V" shape between the divergence of the Cordillera de Merida (to the east) and the northern extension of the Andes (Cordillera Oriental). The largest outlier, ranging from 100 and 300 meters above sea level (masl), is separated from the core region by a transverse dry belt surrounding the lake. The two remaining outliers are located on the eastern side of the lake on Cerro Cerrón (1,900 masl), and a hill on the south (1,578 masl) along the foothills of Cordillera de Mérida.
The ecoregion comprises mountains and valleys. Some of the rivers that traverse the south and western areas are the Catatumbo, Bravo, Santa Ana, and Onia. The Palmar, Apón y Santa Ana rivers come from the Serrania de Perijá. The highest rainfall occurs in the southwestern edge of the Maracaibo basin due to the prevailing winds, bringing clouds, which are then trapped, in the "V" shaped cordilleras. The annual precipitation in this area may reach 4,300 millimeters (mm).
Considering the richness of the area, the existing botanical knowledge is very poor. The most common families are Bombacaceae, Combretaceae, Lecythidaceae, Leguminoseae, Sapotacea, Tiliaceae, and Vochysiaceae. Some of the flora in the upper canopy (40 m) include Anacardium excelsum, Carapa guianensis, Ceiba pentandra, Coumarouna punctata, Couroupita guianenesis, Escheweilera sp., and Sterculia apetala; in the middle canopy (approx. 20 m): Calophllum brasiliense, Guarea thichioides, Parkia pendula, Pentaclethra macrobola, and Swartzia sp.; and in the lower canopy (approx. 10 m): Grislea sp., Inga sp., Luehea sp., Protium sp., Trichilia pleeana, and T. maynasiana. The region also includes Gustavia hexapetala, Cariniana pyriformis, Faramea capillipes, Ochoterenaea colombiana, Miconia mocquerysii and Vochysia lehmannii.
Some areas in the western and southern part of the ecoregion are impacted by anthropogenic activities. Logging, agriculture, and extension of grazing have degraded the area resulting in secondary vegetation including the following genera: Casearia, Cecropia, Croton, Inga, Isertia, Jacaranda, Trema, and Vismia.
The Catatumbo moist forest located south and west of Lake Maracaibo is considered a Pleistocene refuge for woody plant families. This forest is the only area on the northern side of the Andes that still contains remnants of the Amazonian flora of Brazil and Colombia. Various relict species are particularly found on the lower forested slopes along the Rio Onia located south of Lake Maracaibo. Faramea capillipes is an example of an isolated species found along the Rio Onia. Other species of lowland tropical forests that are associated with the Faramea are Tapirira guianensis (Anacardiaceae); Diplasis karataefolia (Cyperaceae); Maprounea guianensi (Euphorbiaceae); Olyra micrantha (Gramineae); Leandra solenifera, Miconia barbinervis, M. nervosa, and Mouriri myrtifolia (Melastomataceae); Abuta pahni (Menispermaceae); and Psychotria capitata inudata (Rubiaceae). Some of the relict plant species found in Catatumbo and in eastern Colombia are Ochoterineae colombiana (Anacardiaceae); Miconia mocquerysii (Melastomataceae); Palicourea buntingii (Rubiaceae); and Vochysia lehmannii (Vochysiaceae).
Endemic flora of the Catatumbo forests include species in the Araceae family—Anthurium praemontanum, Philodendron mesae, Rodospatha perezii, and Spanthiphyllum perezii, and the gesneriaceous Besleria ornata, which is related to B. immitis of the Colombian and Peruvian Amazon.
Little is known about the fauna in the Catatumbo moist forest. The brown hairy dwarf porcupine (Coendu vestitus), an extremely rare mammal, inhabits warm lowlands to higher elevations of about 2,600 meters (m). Few specimens of this porcupine have been collected. Information about endemic animals found in the ecoregion is not available.
Substantial areas of natural vegetation have been destroyed around Lake Maracaibo, affecting moist and dry forests. The extensive network of roads surrounding Lake Maracaibo has fragmented the area. Some areas of the ecoregion have been severely altered by livestock grazing, agriculture, and oil exploration. Deforestation for shifting cultivation has destroyed the forests in mountain slopes. The most degraded areas are in the southwestern side of the region, which is the area proposed as a forest refuge by Steyermark.
The only protected area in the ecoregion is Catatumbo Bari National Park (IUCN category II), located in the eastern section. However, most of the 158,125-hectare Park is located in the Cordillera Oriental montane forests, and little of the moist forests are protected.
Types and Severity of Threats
This ecoregion has an endangered to critical degree of threat. Some of the major threats include:
- Progressive deforestation due to increasing colonization; and
- Oil exploration.
Justification of Ecoregion Delineation
The delineations for this ecoregion were derived from vegetation maps of Huber, who classified this regions as "Lowland Evergreen Ombrophilous Forests", with elements of seasonally inundated wetlands. The UNESCO map confirms this, and their classification as Tropical Ombrophilous Swamp Forest and Tropical Tall Flooded Grasslands confirms the basic habitat type – but linework between these two maps are dissimilar. Our linework however, was derived from Robert F. Smith, who has extensive experience in the area and was better able to separate out the original forest cover. This ecoregion is distinct due to its isolation from similar forests, and its enclosure in this northernmost fork of the Andes – which has led to moderate levels of species endemism and acts as a refuge for many moist forest species in an otherwise arid landscape.
- Emmons, L. H. 1997. Neotropical Rainforest Mammals. The University of Chicago Press, Chicago. ISBN: 0226207218
- Huber, O. and D. Frame. 1988. Venezuela. In D. Campbell and H. D. Hammond , editors. Floristic Inventory of Tropical Countries. The New York Botanical Garden, Bronk. ISBN: 0893273333
- Huber, O. and Clara Alarcon. 1988. Mapa de Vegetacion de Venezuela. Republica de Venezuela, Ministerio del Ambiente y de los Recursos Naturales Renovables, Caracas, Venezuela.
- Prance, G. T. 1982. Forest Refuges: Evidence from Woody Angiosperms. In Ghillean T. Prance, editor. Biological Diversification in the Tropics. Columbia Univeristy Press, New York. ISBN: 0231048769
- Smith, R.F. Personal communications. June 16, 1994. Letters concerning the classification of N. Venezuelan ecoregions.
- Steyermark, J. 1982. Relationship of Some Venezuelan Forest Refuges with Lowland Tropical Floras. In Ghillean T. Prance, editor. Biological Diversification in the Tropics. Colombia University Press, New York. ISBN: 0231048769
- UNESCO. 1981. Vegetation Map of South America: Explanatory Notes. UNESCO, Paris. ISBN: 923001933X
- UNESCO. 1980. Vegetation map of South America. Map 1:5,000,000. Institut de la Carte Internationale de Tapis Végétal. Toulouse, France. ISBN: 9230998621
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