Location and General Description
This moist forest ecoregion is situated on the Gulf of Mexico’s northeastern coastal plain of Mexico, in the north of Veracruz and the south of Tamaulipas states. The ecoregion encompasses lowlands of the eastern slopes of the Sierra Madre Oriental. It is composed of sedimentary rocks from the cretaceous period, and the abundance of this material is responsible for the carstic topography of the ecoregion. The resulting soils are shallow but rich in organic matter (Valiente-Banuet et al.1995).
The climate is tropical humid, with rains during seven months of the year with mild temperature oscillations. The precipitation levels range between 1100 and 1600 mm each year. Although many authors regard this ecoregion as an area of pristine and undisturbed moist forests, the most recent studies demonstrate that only small areas of intact moist forests remain. These remnants are restricted to small areas where steep terrain offers protection. However, the few areas that still contain moist forest assemblages also termed "Tropical Evergreen Forest" by Martin (1958) are characterized by tall trees reaching up to 30 m, where the dominant species are: Mayan breadnut (Brosimum alicastrum), sapodilla (Manilkara zapota), rosadillo (Celtis monoica), Bursera simaruba, Dendropanax arboreus, and Sideroxylon capiri. In central Veracruz State, in the southern portion of this ecoregion, the forest’s vegetative association changes and the dominant species become mahogany (Swietenia macrophylla), sapodilla (Manilkara zapota), Bernoullia flammea, and Astronium graveolens. In the state of San Luis Potosí, the trees are even taller than in Tamaulipas, although with the same dominant species in the canopy (e.g. Brosimum alicastrum and Celtis monoica). The herbaceous stratum is very well developed, and epiphytes are abundant as well as lichens and fungi.
The moist forests of Veracruz ecoregion constitute the northernmost portions of moist forest and associated subhumid tropical vegetation distributed in Mexico. Veracruz has been described as one of the richest faunistic regions in the west hemisphere (Rappole & Ramos 1985, cited in Challenger 1998), and is one of three regions with the highest insect richness and endemism (Robles-Gil et al. 1993). Birdlife International has included this area in its Endemic Bird Area (EBA) project, due to the rich endemic avifauna of the region (Bibby et al. 1992; Stattersfield et al. 1998). Endemic birds include the green-cheeked amazon (Amazona viridigenalis), Tamaulipas crow (Corvus imparatus), Altamira yellowthroat (Geothlypis flavovelata) and crimson-collared grosbeak (Rhodothraupis celaeno) (Stattersfield et al. 1998). These montane forests have special significance because of their high biodiversity and use as a flyway for migratory birds; however, their degree of deterioration is so high that the forest is now composed of small fragments of vegetation.
Many endangered mammals inhabit these forests, as well as endangered birds. According to Davis et al. (1997) there are also two endemic rodents (Peromyscus ochraventer, Neotoma angustapalata). They are located in and around the area designated as a centre of plant diversity called the Gomez Farias Region and El Cielo Biosphere Reserve, which falls within this ecoregion. Jaguar (Pantera onca), ocelot (Leopardus pardalis), jaguarundi (Herpailurus yaguarondi) and coati (Nasua narica) are some unique yet locally or widely threatened mammal species of this ecoregion.
Large portions of this forest have already been eliminated. At present, very little of the actual vegetation corresponds to the original plant associations and the forests of Veracruz have become restricted to a series of patches scattered north to south from Tamaulipas to central Veracruz. Rzedowski (1978) estimates that the forests have been almost completely destroyed and substituted by scrub and secondary communities. Toledo & Ordoñez (1993) confirm that vast portions of the forests have been extensively logged, resulting in the loss of habitat and biodiversity. From 1900 to 1987, over 18,553 km2 of forest in the state of Veracruz were logged (Barrera-Bassols et al. 1993). Trees are cut down for use in the timber industry. Also, valuable wood is overexploited, but since these species are not abundant, vast portions of forest are logged in search of sufficient quantities of this precious timber (Boege & Rodríguez 1992). Large areas of forest have also been removed the local subsistence farmers as they introduce cattle. Cattle grazing is one of the main factors involved in the destruction of these forests (Toledo et al. 1989). Veracruz is one of the primary cattle farming entities of Mexico (Toledo et al. 1989). Moist forests of Veracruz once occupied most of the state, but now they represent the most transformed ecological zone in the region (Ordoñez & García-Oliva 1992). Approximately 64% of the state of Veracruz is subjected to human exploitation, and only 20% of the natural vegetation is intact, with 14% representing secondary communities. Despite the importance of the region as a remnant of humid forest, El Cielo Biosphere Reserve in southern Tamaulipas is the only protected area that has been established.
Types and Severity of Threats
Remaining species and habitats are threatened by human activities and the resulting associated problems. Continued clearing of forest for timber, road construction, expansion of settlements, free roaming cattle, collection of fuelwood, orchids and animals by local people, industrial development and agricultural expansion (Davis et al. 1997). These threats bring consequences with them such as pollution from wastes, clearing of land and alteration of vegetative structure due to gathering of more valuable plants, which are all associated with the expansion of human settlements. Ecotourism is increasing but while economic growth is beneficial to the ecoregion, dealing with more people will call for the improvement of health related systems. El Cielo Biosphere Reserve is also threatened even as the only protected area in the ecoregion; it lacks funding. Timber companies want permits to log the buffer zone (Davis et al. 1997). Cattle enter the forests to graze and people illegally gather plants and hunt animals for their personal subsistence and to sell (Davis et al. 1997). The condition of this reserve will continue to deteriorate until budgets are increased.
Justification of Ecoregion Delineation
The delineations for this ecoregion were derived from the INEGI current landcover maps (1996), from which we lumping montane mesophyll forests classifications with human modified landscapes along the eastern flank of the Sierra Madre Oriental. Linework was then modified by experts at several ecoregion workshops (CONABIO 1996 and 1997) and according to Rzedowski (1978 and pers. comm.). This ecoregion represents the most northerly of the montane moist forests, and are a convergence zone for temperate and tropical flora and fauna – yet remains the northernmost extension of tropical broadleaf montane moist forests in the Americas, and with several endemic species (Stattersfield et al 1999, Davis et al. 1997).
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Prepared by: Alejandra Valero, Jan Schipper, and Tom Allnutt
Reviewed by: Dr. Dan Brooks