Spanning most of Central America, the Mesoamerica Hotspot encompasses all subtropical and tropical ecosystems from central Mexico to the Panama Canal. This includes all of Guatemala, Belize, El Salvador, Honduras, Nicaragua and Costa Rica, as well as a third of Mexico and nearly two-thirds of Panama.
In Mexico, the hotspot extends as far north as northern Sinaloa (Río Fuerte) on the Pacific Coast and as far as the middle of the Sierra Madre Oriental (west of Tampico) on the coast of the Gulf of Mexico, and includes the entire area of the Mexican states of Chiapas, Yucatán, Quintana Roo, Tabasco, Campeche, Veracruz, as well as portions of the states of Oaxaca, Guerrero, Puebla, México, Michoacán, Morelos, Querétaro, Jalisco, Nayarit, Colima, Guanajuato, San Luis Potosí, Zacatecas, Sinaloa, Durango, Sonora, Chihuahua, and Tamaulipas. The hotspot does not encompass the subtropical pine-oak forest in the higher elevations of the Sierra Madre Oriental and Occidental ranges, here included in the Madrean Pine-Oak Woodlands Hotspot.
This hotspot also includes a number of nearshore and offshore islands in both the Caribbean Sea and Pacific Ocean, which are important biologically due to the presence of endemic species and as nesting areas for seabirds. These islands include the Revillagigedos, Tres Marías Islands, and Cozumel, all belonging to Mexico, Islas de la Bahía (Honduras), Cocos (Costa Rica), Providencia and San Andrés (Colombia), and Coiba (Panama), as well as Clipperton Island (France).
The hotspot's major ecosystems are a complex mosaic of dry forests, lowland moist forest, and montane forests. Intermittent coastal swamps and mangrove forests along the Pacific coast from Mexico to Panama give way to broad-leaved and coniferous forests at higher altitudes. East of the mountains, the Caribbean lowlands are home to moist, subtropical wet forests and rain forests. In the southern part of the hotspot, broad-leaved premontane and montane hardwood forests occupy steep and cloud-shrouded slopes.
Unique and Threatened Biodiversity
The biodiversity of Mesoamerica represents the confluence of flora and fauna from two biogeographic regions, the Nearctic of North America and the Neotropical of South and Central America and the Caribbean. North and South America were once two separate landmasses, with independently evolved plant and animal species. Then, about three million years ago, sections of Central America rose above sea level, forming a land bridge between north and south. Species began to flow in both directions between the continents, and their interaction in this transition zone helped produce Mesoamerica's unique and diverse array of life forms.
Additionally, the highlands and mountain chains that run along the hotspot's main north-south axis have facilitated isolation and speciation throughout Mesoamerica. Because the mountains have often posed an impassable barrier, there are considerable differences in species composition between the Pacific and Caribbean coasts. On the other hand, the valleys and lowlands running parallel to the mountains have long served as natural corridors for animal and human migrations.
Mesoamerica has a total of about 17,000 species of vascular plants, nearly 3,000 of which are endemic (17 percent). In addition, 65 of 2,523 genera are endemic, 50 of which are represented by a single species. The number of species and genera endemic to this hotspot is lower than might be expected, because a large number of genera spill over into the neighboring Mexican states of Oaxaca, Veracruz and Tamaulipas. The plants of Mesoamerica provide a window into the unique role of this region as a land bridge between the flora and fauna of North and South America. Many Nearctic and Neotropical plants reach their southerly and northerly range limits, respectively, in this hotspot. The highlands of Guatemala are the northernmost reaches for the páramo vegetation of the northern Andes, including the families, Umbelliferae and Compositae. The coniferous forests of Mexico, Guatemala, El Salvador, Honduras, and Nicaragua represent the southernmost extension of several genera of trees, including Pinus, Abies, Juniperus, Cupressus, and Taxus. Commercially valuable timber species are found within the hotspot and, as in the case of big-leaf mahogany (Swietenia macrophylla, VU), have historically driven the exploitation of the region's forest resources. Other valuable timber species include Pacific mahogany (Swietenia humilisi, VU), extirpated from much of its natural range, Spanish cedar (Cedrela odorata, VU), and rosewood (Dalbergia stevensonii). The hotspot also contains more than 300 cacti species, of which about 60 percent are endemic, or nearly so, to the hotspot (and 85 percent of these are found exclusively within the Mexican portion of the hotspot). Plant endemism is highest within Mesoamerica in the diverse topography of the region's mountains, especially the high mountains of Guatemala and southern Mexico. Three plant families are endemic to the hotspot, each represented by a single species: Haptanthaceae (Haptanthus hazlettii), Lacandoniaceae (Lacandonia schismatica), and Ticodendraceae (Ticodendron incognitum). Lacandonia is particularly unique among flowering plants for having "inside-out" flowers, i.e., the central androecium (stamens) surrounded by the gynoecium (separate pistils).
The forests of Mesoamerica are home to nearly 1,120 bird species, including more than 200 species restricted to the region. About 20 bird genera are endemic to the hotspot, and BirdLife International has identified 17 Endemic Bird Areas in Mexico and Central America, covering nearly the entire extent of the hotspot. The best known species from this region and conservation symbols for their cloud forest habitats are the resplendent quetzal (Pharomachrus mocinno), whose brilliant green and crimson plumage is the national emblem of Guatemala, and the horned guan (Oreophasis derbianus, EN), a large bird – sole representative of its genus – with a distinctive red horn protruding from the top of its head. Both of these endemic species are threatened by habitat destruction. Of the more than 40 species of threatened birds found in this hotspot, endemics include the Honduran emerald (Amazilia luciae, CR), the Cozumel thrasher (Toxostoma guttatum, CR) and the Socorro mockingbird (Mimodes graysoni, CR). The forests of Mesoamerica, the third largest in any of the hotspots, also provide critical winter habitat and stop-over points for about 225 species of migratory birds. Three of the four major trans-regional migratory bird routes in the Western hemisphere converge here.
Mesoamerica holds roughly 440 mammalian species, and more than 65 (15 percent) of these are endemic. A number of these endemics are confined to offshore islands, including two threatened species on Cozumel: the Cozumel harvest mouse (Reithrodontomys spectabilis, EN) and Cozumel raccoon (Procyon pygmaeus, EN). Some of the most visible symbols of mammal diversity in Mesoamerica are its monkeys, including the Central American spider monkey (Ateles geoffroyi) and Mexican black howler monkey (Alouatta pigra, EN), which produce impressive roars that can be heard for miles, and Central American squirrel monkey (Saimiri oerstedii, EN). Two other large mammals, the Baird’s tapir (Tapirus bairdii, EN) and the jaguar (Panthera onca) are both important flagships for the regions forests. However, much of the mammal endemism in Mesoamerica is attributable to the diversity of small mammals. Some 20 species of shrews and more than 180 species of rodents (including nearly 20 species of pocket gophers, and around 20 species of squirrels) are found in Mesoamerica; many of these are endemic. Three endemic species, Van Gelder’s bat (Bauerus dubiaquercus), the Yucatán vesper rat (Otonyctomys hatti), and Bang’s mountain squirrel (Syntheosciurus brochus), are all representatives of endemic genera.
Mesoamerica has very high reptile and amphibian diversity and endemism. The area is the most diverse hotspot for reptiles, with more than 690 species found here, and nearly 240 (35 percent) endemic. Many genera are endemic, as is one monotypic turtle family, the Dermatemydidae, represented by the Central American river turtle (Dermatemys mawii, EN) from the rivers of southern Mexico and adjacent Guatemala and Belize, and one of the most highly threatened freshwater turtles in the world. Another endemic reptile found in many of the same rivers is Morelet’s crocodile (Crocodylus moreletii). There are also many important nesting beaches for marine turtles, including Tortuguero, Costa Rica —one of the most important nesting beaches for green turtles (Chelonia mydas, EN) in the Western Hemisphere. Other beaches on both the Caribbean and Pacific coasts also provide important nesting areas for hawksbill (Eretmochelys imbricata, CR), olive ridley (Lepidochelys olivacea, EN), and leatherback (Dermochelys coriacea, CR) sea turtles.
Amphibian diversity and endemism also reach exceptional levels in Mesoamerica, with more than 550 species, over 350 of which are endemic. Over 20 percent of the 52 amphibian genera in the hotspot are endemic. Guatemala and the adjacent Mexican state of Chiapas are especially rich in salamanders, and are considered a center of origin and dispersal for tropical salamander species. In total, the hotspot has approximately 160 species of the order Caudata (the newts and salamanders), and some 120 are endemic; all endemics belong to the family Plethodontidae (lungless salamanders). One of the most poignant symbols of conservation in Mesoamerica and worldwide is the golden toad (Bufo periglenes, EX). A beautiful, bright orange toad found only in Costa Rica's Monteverde Cloud Forest, the golden toad hasn't been seen since 1989, when it disappeared virtually overnight. The plight of the toad, which is presumed to be extinct, is an oft-cited example of the worldwide phenomenon of declining amphibian populations. In total, more than 230 species of the amphibians present in this hotspot (just less than half) are threatened with extinction, particularly the salamanders in the genus Bolitoglossa and the frogs in the speciose genus Eleutherodactylus.
Freshwater fishes are an important component of Mesoamerica’s vertebrate diversity. The hotspot is home to more than 500 fish species, nearly 350 of which are endemic; there are also 25 endemic genera. More than 200 of the hotspot's fish species belong to two families: the cichlids (with 12 endemic genera) and the live-bearing Poeciliidae. Nearly a quarter of Mesoamerica’s fishes have distributions restricted to single bodies of water or small tributaries in larger watersheds.
Prior to the arrival of the Spanish conquistadores 500 years ago, Mesoamerica supported intensive indigenous agriculture and hunting. With the arrival of Cortez, indigenous populations were decimated by disease, warfare, and slavery, and some of their agricultural clearings were abandoned to regeneration, yielding in some areas a net increase in forest lands. However, during the 19th century, the conversion of forests for large-scale agricultural and livestock developments, including coffee, bananas, oil palm, and beef cattle, began in earnest. Much of the western Pacific plain was cleared by the end of the 1800s, and the focus of conversion during the 1900s was shifted to the tropical moist forests of the Caribbean lowlands.
The advent of mechanized forestry in the 20th century allowed timber operations to abandon rivers and lagoons as the only method of transportation for logs in the tropical forests of Mesoamerica. Aside from riparian areas and adjacent areas that could be reached by oxen, most forests had remained intact largely because they were unharvestable with the available technology. Once timber extraction was mechanized, the presence of big-leaf mahogany, even today the most valuable timber species in the Neotropical forest, was a powerful incentive for logging to open virgin forests. Old-growth mahogany trees could be large enough and valuable enough to prompt extensive exploration; their procurement was the beginning of a multitude of pressures on these forests that escalated once they were relieved of their most valuable species.
In recent decades, Mesoamerica has seen some of the highest deforestation rates in the world; between 1980 and 1990, deforestation averaged 1.4 percent annually, and it is estimated that 80 percent of the area's original habitat has been cleared or severely modified. Of all the countries in the hotspot, El Salvador is the most devastated; it has less than five percent of its original forest cover remaining.
Recently, large-scale industrial developments, including oil development in Mexico and Guatemala and timber and mineral extraction, have increased the threat to forests. Deforestation often follows a familiar and devastating pattern in Mesoamerica, driven by inequities in land distribution and very high population growth rates (as high as seven to ten percent per year in some parts of southern Mexico and northern Guatemala). Roads built for development projects open up access to previously pristine lands and serve as migration routes for landless peasants, who clear adjacent lands for subsistence agriculture. Once the lands, which typically have very poor soils, become unproductive, the peasants clear other areas, selling their original plots to consolidators who develop large cattle ranches in their wake.
Conservation Action and Protected Areas
About 13 percent, or 142,000 km2, of the total land area of the Mesoamerica hotspot is currently under some form of protection, though only 64,000 km2 (six percent) of this is in IUCN categories I to IV. In two countries, national percentages for protected land are more than twice the hotspot average: Belize (37 percent) and Costa Rica (31 percent). El Salvador has the lowest percentage of protected land area; approximately two percent of the country is under protective status.
Many of the parks in Mesoamerica exist on paper only and need improved enforcement and management in order to effectively conserve biodiversity. The integrity of many protected areas is further threatened by communities that live in or around the parks and must poach for food or clear agricultural lands within park borders in order to meet their basic needs.
In recent decades, there has been important progress in regional cooperation and dialogue toward the creation and expansion of the transnational Mesoamerican Biological Corridor, a regional initiative aimed at conserving biodiversity and ecosystems while at the same time promoting sustainable social development social and economic development. The initiative attempts to protect important areas for biodiversity and provide connectivity between these areas through biodiversity-friendly plantation forests, agroforestry systems, and private reserves, to allow for the dispersal of plants and animals. Mesoamerican countries have been eager to participate in the creation of the corridor because it provides a tangible goal in the face of daunting conservation priorities. Among the important protected areas that comprise this initiative are the Maya Biosphere Reserve in northern Guatemala, a 10,000-km2 expanse of tropical forest; the Calakmul Biosphere Reserve in Campeche, Mexico, with 7,000 km2; the Montes Azules Biosphere Reserve in Chiapas, Mexico, covering 3,300 km2; the Rio Bravo protected area in Belize; La Amistad International Park and Biosphere reserve in Costa Rica and Panama, the largest block of undisturbed cloud forest in Central America and a convergence point for 75 percent of all migratory birds in the Western Hemisphere; and Guanacaste Conservation Area in northwestern Costa Rica.
One method for identifying priority areas for the expansion of protected areas systems is by identifying sites for species that face the greatest risk of global extinction. Globally threatened species are best protected through the conservation of sites in which they occur; these sites are referred to as "key biodiversity areas" (KBAs). KBAs are discrete biological units that contain one or more globally threatened or restricted-range species, and can potentially be managed for conservation as a single unit. In the Mesoamerica hotspot, Conservation International and partners have been working on KBA identification in the northern portion (Mexico east of the Isthmus of Tehuantepec, Belize and Guatemala), Costa Rica, and Panama, building off of the Important Bird Areas identified by BirdLife International partners in Mexico and Panama. The process will continue as the collaboration expands to include all the countries of the hotspot during the next year. The La Amistad International Park in Costa Rica and Panama, the only place in the world from which the salamander Oedipina grandis (CR) has been recorded, is an example of the potential for developing a regional network of transboundary protected areas. Here the Critical Ecosystem Partnership Fund is facilitating a regional approach to protecting Mesoamerica’s biodiversity by supporting bi- and tri-national conservation initiatives. The Cerro El Pital between Honduras and El Salvador, a site protected only on the Honduran side of the border by the Cerro El Pital Biological Reserve, and the only place in the world where the frog Bolitoglossa synoria (CR) occurs, serves as another example of the potential for expanding the network of protected areas through transboundary conservation intitiatives.
Ecotourism has become an important sector in nearly every country in Mesoamerica, notably Costa Rica, which is probably the world's best-known example of the successful promotion of economic benefit from conservation. In 2000, Costa Rica earned about $1.25 billion from ecotourism, and it is estimated that 70 percent of the country’s tourists visit natural protected areas.
In addition, several national-level institutions for biodiversity conservation, including INBIO in Costa Rica and CONABIO in Mexico, are successfully promoting greater awareness and sustainable use of biodiversity, while smaller local institutions, such as the Belize Zoo and Mexico's Miguel Alvarez del Toro Zoological Park, promote knowledge, pride, and conservation of native fauna among the citizens of Mesoamerica.
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