Talamancan montane forests

Category: Forest Biomes.

Geographic Location: Central America.

Summary: One of the largest undisturbed forest areas in Mesoamerica, and home to many endemic species, these forests are a vital crossroad for species and ecosystems between South and North America.

Located between Costa Rica and Panama, the Talamancan montane forests represent some of the most intact ecosystems in Mesoamerica. Occurring at 2,461–9,843 feet (750–3,000 meters), this biome includes the largest number of endemic (found nowhere else) species for both countries and one of the richest for the entire region. The area remains mostly undisturbed due to its effective protection under national and international categories, but mostly due to its isolation and inaccessibility.

The region is considered to be the main stepping stone for temperate species from the south and north in the isthmus, a refuge from the Pleistocene, and an independent biogeographic region. The isolation that maintains the area in a good conservation status also represents a unique opportunity for speciation, retaining an important proportion of endemic (found nowhere else) species.

The Talamancan Montane Forests biome is composed of a large intact and continuous forest patch from central Costa Rica south to western Panama. It is almost entirely covered by protected areas, including national parks, indigenous reserves, and an international park shared by the two countries. Due to its biological uniqueness, the area has been designated as a Biosphere Reserve and a Human Heritage Site, and is listed in several global prioritization categories, including Endemic Bird Areas, Key Bird Areas, Key Biodiversity Areas, and Centers of Plant Diversity.

The region includes the highest peaks in both Costa Rica and Panama, such as Cerro Chirripó at 12,467 feet (3,800 meters), Kamuk, and Fabrega. The ecoregion ranges up to 9,843 feet (3,000 meters), where vegetation, solar radiation, and extremely low temperatures create a unique habitat zone of grasslands and marshes known as páramos, a formation typical of the Andes but present in the northernmost range in the Talamancan Mountains, albeit without the characteristic South American Espeletia spp.

The typical climate is temperate, with high precipitation and two marked seasons, rainy and dry. However, even during the dry season, the region is very humid and retains high atmospheric moisture levels. Precipitation ranges from 98 to 256 inches (248 to 650 centimeters), occurring as rainfall and cloud drip. This last effect also creates a unique environment that produced important epiphyte richness in most of the elevation range. Above 9,843 feet (3,000 meters), temperature falls dramatically, so plant communities become limited to those species that are tolerant of frost.

Vegetation

Talamancan includes three main ecosystems: the seasonal rainforests on the Caribbean slopes, the seasonally dry but mostly evergreen forests on the Pacific slopes, and the perpetually dripping cloud forests on the higher elevations. The typical ecosystem found in the Talamancan forests is dominated by mixed stands of oak trees (Quercus spp.) and other vegetation formations. In the entire region, the ecosystems are dominated by Quercus costaricensis and Q. copeyensis, while Magnolia, Drymis, and Weinmannia are important elements. However, the northern portion includes areas dominated by species of the Lauraceae family.

In general, vegetation types occur in three elevational belts, creating unique species associations related to slope, temperature, and precipitation. These belts are the premontane belt at 1,969–4,921 feet (600–1,500 meters), the lower montane belt at 4,265–8,202 feet (1,300–2,500 meters), and the montane belt at 8,202–10,499 feet (2,500–3,200 meters), the latter forming a slow gradual transition to páramo.

Biodiversity

For most of its fauna and flora groups, Talamancan is one of the areas of highest richness and endemism in Central America. Its unique biogeographical features, isolation, and location make it an important area for speciation processes. As the main crossroad for southern and northern biota during all the important biodiversity exchanges between continents, the Talamancan Mountains are a unique mixture of elements from North and South America.

La Amistad International Park, shared by both countries, alone contains some 10,000 vascular and 4,000 nonvascular plant species, including several hundred endemic plant species. The range as a whole is estimated to retain nearly 90 percent of all Costa Rica’s plant species.

More than half the avifauna of the highlands of Costa Rica and western Panama is endemic to the region. Endemism among amphibians is high; even in recent expeditions, new amphibian species, especially salamanders, have been described. Also, the area is considered to be the last refuge for various threatened amphibian species that disappeared from several other regions due to climate change and diseases, but have been rediscovered in this biome.

In terms of mammals, the area includes at least 16 species considered to be regional endemics, and 14 rodent, two shrew, one rabbit, one primate, and one bat species. The area also retains the highest number of threatened mammal species, globally and nationally, in Costa Rica. It is one of the only viable habitats for various larger mammal species such as jaguar, puma, tapir, and red brocket deer.

The region’s endemic mammal species include Dice’s cottontail (Sylvilagus dicei) and some pocket gophers (Orthogeomys spp.). Among the representative mammal fauna of Talamancan are the Baird’s tapir (Tapirus bairdii), jaguar (Panthera onca), and puma (Puma concolor). The small spotted cat varieties (Leopardus spp.) are well-represented here, especially the oncilla (L. tigrinus), limited to the high portions and reaching its northern range limit in Talamanca. Amphibians and reptiles in Talamancan are often unique, and many species are endemic; salamanders are especially rich.

Bird diversity is high in this biome, which includes three Important Bird Areas for Costa Rica. Among the most representative are the magnificent resplendent quetzal (Pharomachrus mocinno), the vulnerable three-wattled bellbird (Procnias tricarunculatus), bare-necked umbrellabird (Cephalopterus glabricollis), the near-threatened black guan (Chamaepetes unicolor), and the harpy eagle (Harpia harpyja).

Environmental Threats

The region retains almost 75 percent of its original cover, but as in most tropical biomes, deforestation, hunting, and extractive activities such as coal production threaten the ecoregion. About 40 percent of the region is officially protected, requiring law enforcement and active management of protected areas. As part of La Amistad International Park, the Talamanca forests have the added benefit of be-ing a United Nations Educational, Scientific and Cultural Organization (UNESCO) World Heritage Site. Climate change impacts on this sensitive area may be especially severe; cloud forest habitats are especially sensitive to changes in the balance of humidity, temperature, precipitation, and air pressure regimes.

Bibliography

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