Location and General Description
Jamaica is the 3rd largest island of the Caribbean archipelago, is approximately 230 km long, 80 km wide at the center and covers an area of approximately 11,500 km2. The island of Jamaica, which emerged from the ocean in the mid-Miocene, has never been connected to any other landmass. Jamaica ranks fifth among the world's islands and with the highest percentage of endemic flora. The island consists of two main mountain ranges, the John Crow Mountains in the east, which are limestone outcroppings, reaching a maximum height of 1,000 m, and the Blue mountains, which are igneous shale reaching 2,290 m (Anon 1987). The southern coastal plains are broad, and include flat alluvial areas, swamps, and dry hills of the neighboring ecoregions. The land surface is two-thirds limestone, the rest is composed of igneous rocks, sedimentary shale and alluvium. Mean annual rainfall varies from less than 750 mm to more than 7,000 mm; rainfall increases with elevation (Anon. 1989).
This ecoregion comprises approximately 85% of Jamaica’s terrestrial area and covers all of the island except coastal areas and lowland dry forests. At present, only the most remote and inaccessible forests on Jamaica are considered original and undisturbed. In 1983, less than 67,000 ha (6%) of Jamaica was covered in undisturbed natural forest. In 1995, the World Resources Institute ranked it as the country with the highest deforestation rate (Hoagland et al. 1995). Three broad groups of forest occur in this ecoregion: limestone forests, predominantly shale forests and alluvial and wetland forests of the coastal plains (Johnson 1988). Development threatens this ecoregions forests as coastal residents seek to escape the high temperatures of lower elevations. The WWF/IUCN study publication; Centers of Plant Diversity and Endemism (Davis et al. 1997) recognizes 2 critical areas in Jamaica, totaling 700 km2 (the Blue and John Crow Mountains and Cockpit Country). The limestone forest flora of the Blue and John Crow Mountains contains more than 600 species of flowering plants and includes about 275 vascular plant species and14 varieties which are endemic to Jamaica. About 87 vascular plant species or 33% of Jamaica’s endemic vascular plant flora, are strictly endemic to the Blue and John Crow Mountains.
Cockpit Country consists of evergreen seasonal forest, mesic limestone forest and degraded mesic limestone forest. In valleys, human interference has resulted in areas of pasture and some agricultural crops. The whole region is estimated to contain 1500 vascular plant species, of which 400 are endemic to Jamaica, including 100 species of angiosperms and one species of fern which are strictly endemic to the Cockpit Country. According to Proctor (1986), there are 106 species which, in Jamaica, are only found in the Cockpit Country. Strict endemic species are best represented in the families Rubiaceae (11 spp.), Compositae (9 spp.), Gesneriaceae (8 spp.), Euphorbiaceae (7 spp.), Orchidaceae (7 spp., in the genus Lepanthes) and Myrtaceae (6 spp.). Floristic studies indicate that each limestone knoll can support distinctly different plants, including those which are endemic to just one knoll.
Of 3,003 species of flowering plants recorded from Jamaica, 830 (28%) are endemic; of 579 fern species 82 (14%) are endemic; and within the Bromeliaceae and Orchidaceae, both of which are richly represented on Jamaica, endemism is 31% (Davis et al. 1986).
More than twenty endemic birds species occur (more than on any other oceanic island in the world) on the island of Jamaica with the number of species almost doubling in the winter due to the arrival of migrants from North America (Downer & Sutton 1990). Most of the birds occur in the forests throughout the island, an exception being the recently split red-billed and black-billed streamertails (Trochilus polytmus and T. scitulus) the latter of, which is confined to eastern Jamaica including the Blue Mountains. Many of the bird species are suffering declining population numbers due to habitat loss and illegal hunting for foreign collectors or by farmers for crop protection. The endemic Jamaican least pauraque (Siphonorhis americanus) is thought to be extinct (Greenway 1967), but some scant evidence suggests it may still survive (Collar & Andrew 1988).
Reptile and amphibian diversity is equally rich as is represented by the number of endemics. Jamaica boasts 27 island endemic reptile species and 20 island endemic amphibian species. Endemics specific to this forest ecoregion are Sphaerodactylus richardsoni, S. semasiops, Anolis garmani, A. reconditus, Eleutherodactylus grabhami E. griphus, E. jamaicensis, E. junori, E. luteolus, E. nubicola, E. orcuttia, E. pantoni, and E. sisyphodemus (Johnson 1988). The Indian Mongoose (Herpestes auropunctatus), first introduced to Jamaica in 1872 (Hoagland et al. 1989), is an adaptable species that has had a profound effect on native vertebrates, especially reptiles and amphibians (Mittermaier et al. 1999). Several endemic butterflies, (Papilio homerus, Eurytides marcellinus) and most of the more than 500 endemic species of Jamaican snails (e.g., Pleurodonte spp. and Annularian pulchrum) are found in this moist ecoregion.
There are three island endemic bats on Jamaica (Artibeus flavescens, Phyllonycteris aphylla, Eptesicus lynni). The sole remaining extant native mammal of Jamaica, the Jamaican hutia (Geocapromys brownii), is found mostly in the remote mountainous regions of eastern, central and southern Jamaica where it is threatened by hunting pressure and habitat loss.
Jamaica has a protected area network with 40 parks and reserves, however, these are largely unmanaged, unmonitored, and neither hunting nor habitat encroachment are effectively controlled (Stattersfield et al. 1998). Staff shortages in relevant agencies are acute and fines for violators of environmental legislation, following successful prosecution, are minimal. In the 1980s the principal obstacles faced when attempting to develop a working park system included lack of public awareness, political support, protected area legislation, and comprehensive park system policy statement. At the same time the need for definition and restriction of management capacity in priority areas developed (Thorsell 1981).
Types and Severity of Threats
Leading environmental concerns include deforestation, soil erosion, population pressures, and lack of public awareness concerning conservation. Mining for a variety of minerals, chiefly limestone, is a serious threat to many of the forests in central Jamaica many of which have never been scientifically assessed. Mining has had a major impact, with bauxite (aluminum ore) mining being particularly important. Perhaps the most immediate serious threat is deforestation as a result of large and small-scale cultivation, principally on the southern slopes of the Blue Mountains, but also in other areas. Deforestation causes massive soil erosion and the quality of the land deteriorates rapidly. Water-courses leading from the mountains become heavily laden with sediment and water flows decrease and become more erratic. This results in water shortages alternating with floods at lower altitudes. Until recently, interior forests were very inaccessible, however, continued road construction into these areas will inevitably lead to increased deforestation and selective cutting.
Justification of Ecoregion Delineation
Our classification for the moist forests of Jamaica are based on conglomerations of the following moist forest types/formations according to Grossman et al (1993) and Brown and Heinman (1972): limestone forest and ruinate, virgin forest, mist forest and elfin woodland, and wet forest fringes and related river valleys. Our classification does not separate out montane formations, which occur between 900-1500m.
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Prepared by: Sean Armstrong
Reviewed by: Rosemarie Gnam (American Museum of Natural History) and Ann Sutton