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Centres of Plant Diversity: the Americas

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CENTRAL AMERICA
REGIONAL OVERVIEW

Introduction
Geology
Total land area:
509,640 km².
Maximum altitude:
4211 m; more than 80 volcanoes.
Physiography
Climate
Population (1991): 29,160,000.
Vegetation: Many types in c. 20 life zones; especially coastal swamp and mangroves, semi-arid scrub, pine (Pinus) savanna, conifer forest, tropical deciduous and semi-deciduous forests, evergreen rain forest, cloud forest, páramo.
Flora
Number of vascular plant species:
16,000-18,000.
Number of endemic species:
3300.
Number of endemic genera:
c. 100.
Number of endemic families:
0.
Useful plants
Factors causing loss of biodiversity
Conservation
Centres
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Introduction

The Central American region is a land bridge connecting North America and South America, extending diagonally from north-west to south-east and separating the Pacific Ocean from the Caribbean Sea. The region extends from c. 7°18°N and comprises 533,726 km² - near the size of Thailand or continental France. At its widest (more or less at the Honduras-Nicaragua border), Central America is c. 480 km across, whereas in the area of the Panama Canal the isthmus narrows to 65 km (Leonard 1987). The region is composed of seven relatively small countries (Table 32) which base their economies on agriculture and use of natural resources.

Natural richness is evident considering that this small tropical region has 20 life zones ranging from semi-desert to cloud forest, with 8% of the world's known plant species and 10% of its vertebrates. Central America "is a delicate strip of land, a region of extremes. It has a distinct, heterogeneous nature with extremely steep terrains, ample variety of climate and perhaps a higher propensity for natural disasters than any other territory on the planet" (Leonard 1987).

Central America is one of the world's richer regions in culture and tradition. It is pluri-cultural and multi-lingual, with more than 43 distinct indigenous-linguistic groups, making up a total indigenous population of 4-6 million people (de Souza 1992). The region is inhabited by Maya groups (e.g. Quiché, Mam, Kaqchiquel, Kekchí) and various others - e.g. Miskito, Guaymí, Lenca, Kuna, Emberá, Sumu, Cabécar, Tol (Xicaque) and Bribri. The largest concentration of indigenous peoples is in Guatemala, where 3-4.5 million Amerindians of 23 different ethnic-linguistic groups comprise 30-50% of the population. Spanish is the official language of Central America except in Belize, where English is primary.

Geology

The region is relatively young, having formed c. 5 million years ago. Only a western archipelago consisting of a series of volcanoes existed during the Jurassic and Cretaceous. The Talamanca Range was formed during the Miocene. During the Pliocene, five tectonic plates converged (the American, Pacific, Cocos, Nazca and Caribbean plates), forming the isthmus of Central America (Heckadon 1992). Only Belize has geologic stability, since it is situated on a portion of a platform of bedrock, which as well underlies the Gulf of Mexico.

The zone of convergence between the Cocos Plate and the Caribbean Plate gave rise to a volcanic chain that borders the Pacific, extending from Guatemala to Panama. Sixty-eight terrestrial volcanoes are included within this chain - three are active in Guatemala, three in El Salvador, more than 15 in Nicaragua and four in Costa Rica. In the last 30 years at least four major earthquakes have affected Guatemala, El Salvador, Nicaragua and Costa Rica, causing thousands of deaths and millions of dollars in damage.

There are four principal geological faults: (1) Motagua, extending across southern Guatemala, at the fracture zone between the North American and Caribbean plates; (2) the highlands of the Pacific, which are characterized by much geological activity related to the shifting of the Cocos Plate; (3) the Nicaragua Depression, which forms Managua and Nicaragua lakes and the San Juan River Basin; and (4) the Chagres River Basin in Panama. These last two fault zones represent the final points at which plates joined to form the Central American land bridge.

The formation of the isthmus of Central America influenced the climatic evolution of the whole planet. It altered marine currents by closing circulation between the Atlantic and the Pacific oceans, and resulted in the formation of a current (the Gulf Stream) flowing north-eastward from the Gulf of Mexico. Another consequence was the major biotic exchange made possible between North America and South America.

Physiography

The convergence of the tectonic plates has resulted in a region of sharp topography, with varied landforms from plains near sea-level to peaks rising over 4000 m (Leonard 1987), which tend to be more precipitous on the Pacific slope. Hillsides and highlands comprise 77% of Central America.

The highland landforms consist of many mountain ranges, volcanoes, valleys and high plateaux. Adding the Maya Mountains which are highest in central Belize, mountainous regions are continuous from Guatemala and northern El Salvador through Honduras and Nicaragua. They are interrupted in the area of the Nicaragua Depression at the San Juan River, which forms part of the border with Costa Rica. The chain of volcanoes begins with the highest Central American peaks, Guatemala's western volcanoes Tacaná (c. 4093 m) and Tajumulco (4211 m), and ends in the Cordillera de Talamanca, which begins near central Costa Rica and extends into western Panama. Several serranías in eastern Panama are near the north-western extension of the Andes of South America.

Narrow plains border the Pacific Coast from Mexico to eastern Panama. Interior lowlands known as the Nicaragua Depression (Limón Basin) extend diagonally southward from the Gulf of Fonseca across the Central American isthmus to the coastal plain of north-eastern Costa Rica. There are lowlands on the Pacific side between the isthmian spine and Costa Rica's Nicoya and Osa peninsulas and western Panama's Azuero Peninsula; in eastern Panama there are lowlands inland from the Gulf of San Miguel in the Darién near Colombia. On the Atlantic side, low limestone tableland sloping north-eastward as the Yucatán Peninsula forms the Guatemalan Petén and northern Belize, which has a broad coastal zone to the Gulf of Honduras. From north-eastern Honduras the northerly much broader flatlands known as the Mosquitia region extend to central Panama (the broad La Mosquitia narrowing southward to the Costa de Mosquitos). The Caribbean coast continues east of the Panama Canal as a rather narrow strip which broadens again in Colombia.

Climate

Central America is influenced notably by its location between two oceanic climates, its chain of high mountains and its highly heterogeneous physiography. Generalizations can be made about the climate based upon average temperatures, annual precipitation and duration of the dry season (Leonard 1987). The lowlands are warmer on both coasts, with gradual change in ascending to the cool and pleasant climate in the temperate zones of the interior.

The total average precipitation tends to increase from north to south. Local climates range from semi-desert areas which receive only 400 mm of precipitation a year to areas of cloud forest with annual precipitation up to 7500 mm. Two seasons exist - the dry or summer season which begins in November, and the rainy season which begins in May. Each - in general - lasts about six months, but the lengths of the seasons vary greatly. There are places where it rains year round, principally in Costa Rica. In contrast, a more accentuated dry season, with less precipitation over intermediate times and annually, is found in some areas on the Pacific side. Some areas are prone to droughts.

The amount of annual precipitation and the duration of the rainy season are the two factors that determine the three principal climatic zones in Central America: (1) the tropical lowlands of the Caribbean region, which are hot and humid, receiving some rain all year; (2) the interior uplands of the isthmus where the temperate climate is cool and damp in the intermontane valleys and plateaux, to cold and cloudy higher on the mountains; and (3) the lower Pacific slope and coastal plains, which have hot and dry conditions, except for intermittent periods of torrential rain between May and October (Leonard 1987).

Population

The population of Central America has grown rapidly over the last few decades; it presently has the world's second highest growth rate - c. 2.8%. The population reached 29,160,000 in 1991, with a projected total by the year 2025 of c. 62 million (Table 33). Sixty percent of the people are in Guatemala, El Salvador and Honduras. In 1991 El Salvador had the highest population density with 261 people per km², whereas Belize had 10 people per km². Nicaragua, Guatemala and Honduras have the highest growth rates. Forty-four percent of the region's population is under 15 years of age.

From 1940 to 1990, the population of Central America more than tripled. During that period an estimated two-thirds of the region's tropical rain forests were cut, burned and converted to agriculture (de Souza 1992; Ypsilantis 1992). Most of the population (c. 90%) remains concentrated in capital cities or along the Pacific slope, where soils are suitable for agriculture and the climate is pleasant. Colonization in recent years has brought about expansion of the agricultural frontier from the crowded Pacific coast and interior regions, by penetrating the forests of the Caribbean coastal plain, which had suffered little destruction prior to the 1940s. New technologies and motorized machinery such as chain saws and bulldozers facilitate building roads and clearing the land.

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The natural environments
and their vegetation

The Holdridge life-zone system has been applied to all of the countries in Central America except the eastern part of Nicaragua (Leonard 1987; Campbell and Hammond 1989). At least 20 bioclimatically distinct life zones are represented. Most of the region east of the continental divide and most of Costa Rica and Panama are in the moist or wet-forest life zones. Montane forest and alpine-like vegetation occur on the highest peaks of Guatemala and Costa Rica. On the western slope, from north-western Costa Rica northward, most of the natural vegetation is in dry-forest life zones. Semi-desert thorny scrub occurs in east-central Nicaragua and Guatemala's Oriente Region.

In considering vegetation types, the published Floras (e.g. dealing with Guatemala, Costa Rica and Panama) have overviews of varying geobotanical scope, but their introductions lack an underlying and uniform system of classification (cf. Campbell and Hammond 1989). Consequently they are helpful in the context of each country but of limited applicability when considering the whole isthmus as interlinked biotic units. The life zones broadly coincide with simplified natural vegetational regimes. For example, high humid forest, oak and deciduous forest, and conifer forest tend to occur in the pluvial, wet, moist and montane forest life zones, whereas low and medium forests and savanna prevail in the dry-forest life zones (Leonard 1987).

Main vegetation biotopes

Gómez (1985) recognized 27 major biotopes in a biogeographical concept for the Neotropical Realm between the boundaries of U.S.A./Mexico and Panama/Colombia (excluding a few areas of continental U.S.A. and the Caribbean Islands). These broad biotopes incorporate the analysis of vegetation with faunal distributions and the climatic patterns. A summary of the intra-isthmian connections is in Gómez (1986); also see Herrera and Gómez (1992). The biotopes are characterized in the following sketch mainly by vegetation in a north to south order by country and generally from west to east. The major vegetational types are based on Gómez's system of biotic units.

1. Guatemala
The country has 12 biotopes, all shared with Mexico:

  • 1.1. Coastal swamp and mangroves, along the Pacific coast without Pelliciera rhizophorae. A highly endangered and reduced zonal habitat, most of which is degraded.
  • 1.2. Southern Sonoran elements in the semi-arid Pacific coastal lowlands. Highly degraded.
  • 1.3. Deciduous and semi-deciduous forests of one or two strata. The dominant arborescent elements to 15 m tall, in semi-open woodland with a high percentage of thorn and microphyllous scrub. Also found isolated in areas of Guatemala's Petén, but with a large number of changes induced by people.
  • 1.4. Exclusively on the Pacific coast, semi-deciduous forest with "cardonales" (succulents and similar plants - e.g. Cactaceae and Agavaceae) and a lower percentage of microphyllous scrub.
  • 1.5. Intermediate vegetation, from approximately 800 m to 1500 m on the Pacific slope and 500 m to 1500 m on the Caribbean side. High percentage of Mexican elements on both slopes. This biotope in Mexico corresponds to the Central American element recognized by Rzedowski, which is described in the Flora of Chiapas (Breedlove 1981).
  • 1.6. Oak and other broadleaved forests, on both slopes. The understorey has abundant representatives of Cactaceae and Agavaceae (forming cardonales).
  • 1.7. Oak and conifer forest. No fewer than seven species of Pinus in various combinations with species of Quercus, Juglandaceae, Liquidambar and Carpinus. With a high percentage of boreal elements which also occur in the Mexican highlands. On the Caribbean slope there is an increasing representation of southern Central American species.
  • 1.8. Mexican-Guatemalan conifer forest. With Pinus, Abies, Juniperus, v Cupressus and Taxus - essentially the southern limit for some of these genera.
  • 1.9. Guatemalan highland meadow. Referred to in literature as "páramo", but Gómez (1985) prefers the concept highland meadow. Rich in boreal elements, this type of vegetation is limited in extent, and confined in Guatemala to the highest volcanic peaks. This zonal habitat is also the northernmost extension of some South American páramo plants, particularly in Umbelliferae and Compositae and for some vascular cryptogams. Little known floristically.
  • 1.10. Petén vegetation. With fewer Mexican-Yucatán elements, this biotope is nevertheless diverse for edaphic reasons, having swamps of fresh or brackish water depending on distance from the coast, as well as limestone outcrops with varying percentages of thick-stemmed and thorny plants (cf. Gentry 1942; Standley and Record 1936). There is a conspicuous presence of regionally endemic cycads (Zamia, Ceratozamia).
  • 1.11. Caribbean lowland rain forest. A rich mixture of broadleaved forests of diverse origins, mostly with Mexican affinities (cf. Standley 1931; Gómez 1986).
  • 1.12. Caribbean lowland pine savanna. Extending from south of the Petén vegetation but including some of its elements. This biotope is characterized by the presence of Pinus caribaea var. hondurensis and Quercus oleoides. It extends, with a significant loss of Mexican elements (particularly Quercus), to the Nicaraguan Mosquitia or Mosquito Coast.

2. Belize

The vegetation of Belize, which is well described by Standley and Record (1936), constitutes a mixture of Yucatán-Petén and Caribbean elements (cf. Standley 1930; Gómez 1986). Belize does not have exclusive biotopes, sharing those presented above for Guatemala in 1.1 and 1.10-1.12. Perhaps the most singular vegetational type in Belize is the halophyte reef community. Belizean vegetation is highly degraded and depauperate as a result of intense human activity since pre-Columbian times.

Amazonian elements are poorly represented in the flora of Belize, in contrast with the other Caribbean coastal wet areas of Central America, where those elements are pervasive and conspicuous. This is partly due to the singular geological configuration and origin of Belize, which is further emphasized by its unusual mammalian and herpetological affinities with the Greater Antilles.

  • 2.1. Halophyte reef community. These communities find their highest diversity in the Belizean keys off the coast. Not only are these communities an indispensable link in the trophic chain that supports an extensive reef system and Caribbean fisheries (both for Belize and Caribbean islands), but there is nothing comparable elsewhere along the entire east coast of Central America. This is an area in urgent need of protection.
  • 2.2. Coastal and lagoon swamps. Populated by Rhizophora, Conocarpus, Pelliciera, Prioria and the palms Manicaria and Raphia.
  • 2.3. Petén vegetation, as described for Guatemala (1.10 above).
  • 2.4. Caribbean lowland rain forest (1.11) (cf. Standley and Record 1936).
  • 2.5. Pine savanna (Miskito savanna). An open woodland dominated mainly by Pinus caribaea var. hondurensis, and also connected by corridors to the higher elevation pine forests with Pinus ayacahuite, P. oocarpa and P. rudis, interspersed with broadleaved species. The savanna extends south, with interruptions, to just north of Bluefields, Nicaragua (5.9 below). Even though this zonal habitat has been much degraded by human activities, natural patches remain of this diverse biotope.

3. Honduras

Basically composed of the same vegetation types that occur in Guatemala, except without those peculiar to the Pacific coast. Inland valleys show a remarkable Pacific climatic influence where there is a predominance of Quercus-Pinus forest, with isolated patches of broadleaved forests that are rich in endemics. The conifer forest is less diverse, for example with Pinus, Liquidambar and Carpinus and no Cupressaceae. Gómez (1985) recognized eight major vegetational types in Honduras:

  • 3.1. Coastal swamp and mangroves. Identical in species composition to those of Belize (2.2), but not as extensive.
  • 3.2. Semi-deciduous broadleaved forest on karst with microphyllous elements in the understorey. A much reduced biotope.
  • 3.3. Lowland pine savannas. In Honduras these may be divided into two subtypes depending on the presence or absence of Quercus oleoides, which reaches its southern limit here on the east coast. Savanna vegetation without Quercus oleoides continues south into the Nicaraguan Mosquitia or Mosquito Coast (5.9).
  • 3.4. The Aguán Valley represents the southern limit of the Yucatán-type vegetation (1.10) within isthmian Central America; for a floristic analysis, see Standley (1931).
  • 3.5. Intermediate area. Situated at 500-1500 m, this zone is a composite of floristic constituents of Mexico and northern South America, with a Mexican predominance. Where soils permit, this zone includes the Central American conifers.
  • 3.6. Oak-pine forest. Occurring at elevations of 900 m and above, this biotope corresponds with the Nuclear Central America region defined by geologists, and marks the southern limit of boreal floristic influence.
  • 3.7. Semi-arid and deciduous inner-valley vegetation. Occurs in the valleys of Comayagua and Tegucigalpa, with many representatives of the Sonoran to isthmian progression. Also in the Choluteca Valley in the south and on the Salvadoran coastal plains (4.2).
  • 3.8. Broadleaved montane forests, well represented on the upper reaches of the Uyuca and San Juancito mountains and on La Tigra. This biotope compares well with forests at similar elevations in Nicaragua (5.7) and northern Costa Rica (6.9).

4. El Salvador

El Salvador has the least national area and the lowest biological diversity in the region. Among the landscapes of Central America, it is also the most altered. Many factors have contributed, but over-population is perhaps the most significant (Pacheco and Martínez 1949). Floristically, the vegetation types are an extension of those mentioned for Honduras, except without those peculiar to the Caribbean lowlands but with the types as found on the Pacific coast in Guatemala.

  • 4.1. Coastal swamp and mangroves, without Pelliciera. As described for Guatemala (1.1) but less expansive. Exploitation of mangroves for fuelwood and tannins has depleted this biotope.
  • 4.2. Southern Sonoran elements on semi-arid coastal lowlands (1.2).
  • 4.3. Deciduous and semi-deciduous forests of one or two strata. Fewer cardonales than in the Guatemalan area (1.4). Occurring on higher and drier slopes in the Trifinio area (where El Salvador borders Guatemala and Honduras) and in the Gulf of Fonseca area. Within historical times there were extensive almost pure stands of Myroxylon balsamum var. pereirae (5.3), which is now very scarce. The narrow riverine valleys contain a larger number of broadleaved evergreen species. Some ravines and canyons eroded from Pliocene diatomite have an interesting calciphilous flora - still evident a decade ago.
  • 4.4. Intermediate area. The natural vegetation much reduced with development of extensive coffee plantations, particularly towards the interior and on volcanic slopes. A few privately protected areas remain, but they are too fragmented to be a potentially viable mosaic for the spontaneous regeneration of natural cover.
  • 4.5. Oak-pine mixed forests (1.7). Forests severely depleted by extraction for fuelwood, and by urban development, preventing their regeneration.
  • 4.6. Conifer forests dominated by Pinus, but with fewer species than the ecologically equivalent areas in Guatemala (1.8) and Honduras.

5. Nicaragua

North of 12°30'N, Nicaragua may be geologically considered part of Nuclear Central America. Biologically, Nicaragua south of this latitude has closer affinities to the younger territories of Costa Rica and Panama. Based on its geological origins, Nicaragua has three major morphotectonic units: (a) Pacific Coastal Plains, mostly a mixture of Quaternary volcanism over remnant older (Cretaceous) outcrops, the Guanarivas Formation and serpentines; (b) Central Highlands, which are plateaux and valleys of tectonic origin; and (c) Caribbean Plains, the northern part being very similar in origin and vegetation to south-eastern Honduras.

Floristic inventories have been conducted, and a comprehensive Flora de Nicaragua is nearing completion. The following vegetation types are identified:

  • 5.1. Coastal swamp and mangroves of the Pacific coast, mostly isolated at the mouths of larger rivers having estuarine conditions. As in other northern localities without Pelliciera, but with it occurring sporadically just south of León. Threats are exploitation of the mangrove wood (and collection of shells).
  • 5.2. Sonoran elements on semi-arid coastal lowlands. Quercus oleoides occurs in patches. There are isolated "vernal" pools with a high proportion of seasonal aquatics toward the south-western part of the country. Occasionally interrupted by volcanic peaks of Quaternary origin with slopes covered by seasonal yet evergreen broadleaved vegetation.
  • 5.3. Deciduous and semi-deciduous forests of one or two strata, with an understorey much reduced in numbers of microphyllous, succulent and thick-stemmed species. North of the Gulf of Fonseca much of this biotope once contained large stands of Myroxylon balsamum var. pereirae (4.3), which has been cut for use in rural construction. Erythroxylum appears from León southward. The vegetation type is also found, isolated by recent volcanic events, in inland areas closer to Managua Lake than to the coast (i.e. Santiago and Masaya volcanoes).
  • 5.4. Intermediate zone, from 500 m to nearly 1000 m. Enriched by having South American elements mixed with the Mexican and Central American elements. This biotope is more extensive and less degraded along Caribbean slopes. In 1991 Nicaragua established the Bosawas Natural Reserve (8000 km²), the largest reserve in the country, protecting a great diversity of ecosystems.
  • 5.5. Oak-pine forest. As described for Honduras (3.6) and El Salvador (4.5), with fewer species of Pinus - including P. caribaea var. hondurensis, P. chiapensis, P. oocarpa subsp. oocarpa, P. patula subsp. tecunumanii and P. pseudostrobus var. oaxacana; the southern limit of the Central American pines is 12°N. Unusual examples of this vegetation type are on calcareous outcrops north of Estelí and on an isolated gently sloping piedmont overlooking the Gulf of Fonseca (and reaching the forest types of 5.3).
  • 5.6. Conifer forest. Some Liquidambar and Carpinus mixed in stands of Pinus (see 5.5). Now limited toward the central northern part of Nicaragua and much reduced by human encroachment and exploitation.
  • 5.7. Montane broadleaved forest. Surrounding the oak-pine forest and conifer forest on both slopes, this biotope finds its maximum development along the Caribbean side. In Guatemala presented in 1.6; rich in diversity and with a high number of endemics.
  • 5.8. Caribbean lowland rain forest. Two regional subtypes: (a) in the north-east near the Coco River and border with Honduras, where less moist than (b) in the very wet south-east, south of the Siuna River (and extending into north-eastern Costa Rica). The wetter southern formation is found on deltaic deposits basically from Bluefields south, and follows the course of the San Juan River westward to Lake Nicaragua.
  • 5.9. Caribbean lowland pine savanna. On sandy loams around Puerto Cabezas and on gleys north and west of Bluefields Lagoon. As described for Honduras (3.3) and Belize (2.5), but more patchy and reduced in extent, and less diverse. Much degraded.
  • 5.10. Coastal swamp and mangroves of the Caribbean, with relictual Pelliciera. Sometimes with extensive outer rings of palm swamp, mostly Raphia and Manicaria. Also inland just south of Castillo with relictual Yucatán-Antillean elements, such as the palm Acoelorraphe on permanent and seasonal waterlogged flat ground.
  • 5.11. Lacustrine communities. Extensive areas dominated by Eichhornia and Pistia. A rich assemblage of hydrophytes, most important for the restoration of the manatee populations (Trichechus manatus) found in the lakes and riverine system that flows into the San Juan River.

6. Costa Rica

This country, together with Guatemala, has received most of the attention in botanical studies. Gómez (1986) discussed in detail the vegetational types of Costa Rica and produced a series of maps that indicated 44 macro-types. Herrera and Gómez (1992) refined the maps and brought the number of biotopes to 56. Several biotopes are being analysed in phytosociological detail by European researchers - high montane oak forest (Kappelle 1995) and páramo (see La Amistad Data Sheet, CPD Site MA17). Costa Rica has designated 27% of its territory with some category of protected status.

For this Regional Overview, these more than 50 biotic units have been grouped to conform to the format of the other six countries as follows:

  • 6.1. Coastal swamp and mangroves. With Rhizophora, Conocarpus and Laguncularia on both coasts, and Pelliciera on the Osa Peninsula and other isolated spots along the Pacific, but not extending north of Bahía Salinas. On the Caribbean shore in estuarine conditions, the mangrove forest may include Prioria. The Tortuguero lagoons and channels of the Caribbean coast constitute an extensive system of aquatic plant communities where many South American hydrophytes find their northernmost distribution. On both coasts these natural resources suffer from over-exploitation.
  • 6.2. Halophyte community. Mainly Thalassia beds, which are shared with Caribbean Nicaragua from just south of Bluefields to Punta Mono (near Panama), and also occur northward in Honduras, Guatemala and Belize (2.1). Although not of significant extent, they are very important in the life-cycles of green and leatherback sea-turtles.
  • 6.3. Santa Elena Peninsula serpentine vegetation, in north-western Costa Rica. A continuation of the contingent in Nicaragua, but rather different even though very sparse and restricted in area. The calciphilous vegetation on the Guanarivas Formation reappears in Costa Rica mostly in the inner arc of the Nicoya Peninsula, representing an isolated Pleistocene relict.
  • 6.4. Deciduous and semi-deciduous forests of Pacific coast. Very similar floristically to those sketched for the rest of Central America (e.g. 1.3, 4.3, 5.3), but the percentage of succulents and thick-stemmed species is negligible. One singular occurrence is Melocactus curvispinus (M. maxonii var. sanctae-rosae), found not only on marine sediments but often on ultramafic layers along the coast. Myroxylon and Erythroxylum are also present and together with the conspicuous cactus Stenocereus aragonii, mark the penetration of this type of vegetation inland and to the west of San José.
  • 6.5. Pacific lowland savanna, with Quercus oleoides (5.2). Vegetation identical to that in the area of influence of the Gulf of Fonseca and the Choluteca area. Quercus oleoides extends up the slopes to c. 800 m, marking the limit of this biotope and the beginning of the intermediate zone.
  • 6.6. Seasonal yet evergreen broadleaved forest. Found in isolated areas along the Pacific coastal lowlands and mid-elevations (see 5.2), often in association with riverine conditions. Extends to the western portion of the Central Valley and in the General Térraba area, surrounded by the Cordillera Costera to the west and the Cordillera de Talamanca to the north and east.
  • 6.7. Lowland rain forest. Below 800 m on the Pacific side and 500 m on the Atlantic slope (cf. 5.8). The Caribbean lowlands are remarkably homogeneous, whereas the Pacific lowlands are less so. The Osa Peninsula shares c. 90% of its arborescent flora with areas in north-eastern Costa Rica (e.g. La Selva - see Data Sheet, CPD Site MA16), but also has an unusual number of disjuncts shared with the Guayanan flora. The forests between the mouths of the Grande de Térraba and Grande de Tárcoles rivers in the south-west are remarkable in having a high number of endemics that have not been found in similarly structured counterpart forests elsewhere.
  • 6.8. Intermediate zone (1.5, 3.5, 5.4). Along the Pacific slope from 800-1500 m and on the Atlantic slope from 500 m, this is the richest and most diverse of the biotopes. It is also one of the more endangered, having climatic and edaphic conditions that promote urban development as well as agricultural activities.
  • 6.9. Montane forest. Found in the Guanacaste, Central Volcanic and Talamanca cordilleras. In Costa Rica including the Quercus forests noted for more northern areas, as well as broadleaved forests without Quercus. The Costa Rican highlands do not have native species of Pinus, whose southern limit is in Nicaragua (see 5.5); the only conifers are Podocarpus and Prumnopitys.
  • 6.10. Mid-elevation and highland savannas of the Talamancas. Three subtypes occur: the hyper-humid savanna of Esperanza, on the western slopes above the Grande de Térraba River; Myrica-dominated savanna, which extends south of Dúrika Massif above 2000 m; and at 3000 m, the "punoid" dry savanna Los Leones, which is mostly composed of bunch grasses.
  • 6.11. Subpáramo and páramo (1.9). Crowning the highest peaks of the Cordillera de Talamanca starting with Buenavista and Cuerici and forming isolated ecological islands above 3000 m.

7. Panama

Panama's location on an east-west axis, instead of the basically north-south orientation of the rest of Central America, accounts for somewhat different climatic patterns. Geologically this is the youngest part of the Central American isthmus. Its connection to the South American land mass nearly 5 million years ago and its unusual topography with highlands at both ends of the country and rather flat areas in the middle, and with the isthmus itself only c. 65 km wide from coast to coast, have contributed to its rich flora. In keeping with the rest of the overview, the vegetation types are:

  • 7.1. Coastal swamp and mangroves. As on both coasts of Costa Rica (6.1), with Pelliciera also found on the Caribbean side.
  • 7.2. Deciduous and semi-deciduous forests. Along the Pacific coast from Punta Burica eastward. Quercus oleoides supposedly reached as far south as Panama City, an assertion for which there is no known herbarium voucher nor mention in the literature. Briefly described by Standley (1928).
  • 7.3. Pacific lowland savanna. Similar to Costa Rican counterpart (6.5), it extends to the west of San Francisco Veraguas where a marked South American llano influence is obvious, particularly in the diversity of vascular cryptogams and aquatic phanerogams.
  • 7.4. Seasonal yet evergreen broadleaved forest (5.2, 6.6), well described in the Flora of the Panama Canal Zone (Standley 1928) and the Flora of Barro Colorado Island (Croat 1978).
  • 7.5. Lowland rain forest. In western to central Panama very similar to Costa Rica (6.7). Based on studies so far, eastern Panama has a higher number of Guayanan-Amazonian elements. Partly because of its relative isolation, botanical explorations have been limited.
  • 7.6. Intermediate zone. As in Costa Rica (6.8); partly included in the Flora of Barro Colorado Island. Standley (1928) pointed out that the Caribbean slope is richer. The flora is different in far eastern Panama, where both slopes have higher diversity and affinities to the Colombian Chocó.
  • 7.7. Montane forest. In two major regions: western Panama on the extension of the Talamanca Range from Costa Rica (6.9); and in the Darién, where species share affinities with neighbouring Colombia (cf. Lamb 1953; Meyers 1969). La Amistad International Park (CPD Site MA17) provides ample protection for these western formations; however, the Pacific slope of the park is badly degraded on the Panamanian side.
  • 7.8. Subpáramo and páramo vegetation (6.11). Richly expressed on Fábrega and Barú massifs. This biotope has many plants occurring especially in Andean South America.

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Flora

Floristically, Central America is the least known part of the world, yet it is extremely rich in numbers of plant species. Of the world's c. 250,000 species of flowering plants, an estimated 15,000-17,000 species live in Central America (Gentry 1978; cf. Davidse, Sousa-S. and Chater 1994). With continued plant exploration and taxonomic studies, these figures could rise, since in the neotropics as many as 10,000 species of vascular plants may be undescribed (Gentry 1982). Floristic knowledge of Central America is still quite limited, although every country has either some checklist or Flora (Campbell and Hammond 1989). Several extensive Flora projects have been finished (Flora of Guatemala by Standley et al. 1946-1977 and Flora of Panama by Woodson et al. 1943-1980), but these works are incomplete and now out of date. Some major publications describing the floras of the region are given in the References section below.

Work began in 1980 on a major project, Flora Mesoamericana, undertaken by the Universidad Nacional Autónoma de México's Instituto de Biología, the Missouri Botanical Garden and The Natural History Museum (London). This project covers the region from the Isthmus of Tehuantepec in Mexico through Central America, and will produce seven volumes treating an estimated 18,000-19,000 native, naturalized and cultivated species in 225 families. A first volume which covers 40% of the monocotyledons has been published (Davidse, Sousa-S. and Chater 1994), and the volume on ferns and fern allies was published in 1995.

For each of the countries in Central America, Table 34 provides estimated numbers of vascular plant species, recorded endemics of the country and threatened species, based on information from specialists and literature gathered for Threatened Plants of Middle America (Villa-Lobos, in prep.). These figures sometimes update those in Table 1 of the CPD Introduction, at least in earlier volumes.

Endemism

A large portion of the flora of Central America is composed of widely distributed species; nevertheless, studies have shown this region also contains a high number of endemic species. Gentry (1982) calculated that the Central American region has 14% endemism, based on estimates of the number of species and the percentage of endemism by predominant habitat group, using available Floras and monographs for geographical distributions.

The greatest concentrations of endemic plants occur high on the mountains. In the early 1970s it was estimated that 70% of the vascular plants of the high mountains of Mexico and Guatemala are endemic, with the high mountains of Costa Rica and Chiriquí in Panama surpassing 50% endemism (D'Arcy 1977). Table 34 gives the percentage of endemism based on recorded endemics in each country; the region's total endemism is c. 19%.

The concept of endemism is relative, and often based on artificial limits such as political boundaries; this is well illustrated in Central America. For example, the family Rubiaceae in Costa Rica has some 405 species, including cultivated, disjunct and possibly occurring species. Removing those three categories of plants, it may be assumed that the Rubiaceae is represented in Costa Rica by 345 species, of which 66 (19%) are endemic to Costa Rica. But, if we instead consider the natural region of the Talamanca-Tabasara ranges and include the data of adjacent western Panama, the number of endemics increases to 109 (32%). Of the 345 species, 83 (24%) range from just Nicaragua to Panama, resulting in a total of 192 endemic species (56%) in that region (W.C. Burger 1993, pers. comm.). Similar perspectives about endemics of narrow and broader geographical ranges are being discovered for many other groups of organisms.

Endemic genera
There are c. 100 genera endemic to Central America, and another 65 genera that are essentially Central American with only one of the several species occurring outside this region (D'Arcy 1977). Intensive collecting in Costa Rica has resulted in the discovery of many monotypic genera - e.g. Gamanthera and Povedadaphne (Lauraceae), and Panamanthus and Gaiadendron (Loranthaceae).

Endemic families
Discovery of new families of flowering plants is uncommon. However, Ticodendraceae was described in 1991 as a result of research conducted in Costa Rica. It is now known to be endemic to Middle America, occurring in mid-elevation cloud forests on both sides of the continental divide through Mexico and Central America.

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Useful plants

The number of economic plants in Central America is very large. The forests and other vegetation are important for example for foods, flavourings, medicinals, oils, dyes, natural pesticides, fibres, wood, energy and ornamentals (Table 35). Major compilations have been published on useful plants in Central America (Morton 1981; Williams 1981), including information on those species that are more or less endemic to Middle America or Central America, or either of these regions and also the Caribbean and/or northern South America.

Many of the timber species are commercially extracted for their valuable wood. Several timber species have been placed on CITES appendices, which regulates their international trade. One of the best known tropical hardwoods is genuine mahogany, represented by a genus of three species in tropical America: Swietenia humilis, which is distributed along the west coast from south-western Mexico to Costa Rica; Swietenia macrophylla, the most widespread of the three, which occurs from southern Mexico through Central America, south to Brazil and Bolivia; and Swietenia mahagoni (the original "genuine" mahogany), restricted in distribution from the Bahamas through some Caribbean islands including Cuba, Jamaica and the Cayman Islands.

In 1992, Costa Rica and the U.S.A. proposed adding the latter two American mahoganies to Swietenia humilis in Appendix II of CITES in order to avoid loss of their wild populations and consequent ecological extinction, by reducing international trade in the woods to sustainable levels. After much controversy in a few countries, S. macrophylla, by far the most heavily traded species, was not listed under this treaty. Swietenia mahagoni was listed, but it was already ecologically compromised and commercially extinct. In 1994, The Netherlands proposed including Swietenia macrophylla in Appendix II, and the CITES countries voted 50 to 33 in favour of doing so, which was just six votes short of the two-thirds of voting countries needed. It was put in Appendix III by Costa Rica in 1995.

Studies are being conducted to inventory and document the numerous species being utilized for medicinal purposes in local cultures. For example, Duke (1985) provided a list of neotropical anti-cancer plants, Balick's floristic checklist for Belize (in prep.) records plant usage, and the world's largest pharmaceutical company (Merck and Co.) made a major investment and agreement in 1991 for bio-prospecting with Costa Rica's National Institute of Biodiversity (INBio) (Booth 1993; Reid et al. 1993).

Various families endemic to or richer in the tropics are important ornamentally, such as Orchidaceae, Bromeliaceae, Palmae and Zamiaceae. Wild-collection of some of these species and/or their cultivation in the region is undertaken for personal use and also for local, national and international markets.

The orchids of Central America are relatively well documented and show considerable diversity (e.g. Hamer 1988, 1990; Williams 1956). They are popular in the region as ornamentals, and a resource for recreation and tourism. Guatemala and Honduras export large numbers of beautiful species. All Orchidaceae are regulated by CITES, to differentiate wild from propagated plants and curtail excessive exportation of the wild plants.

The bromeliad genus Tillandsia has become popular as house-plants and for use as a non-viable decorative in novelties, with grey-leaved species being particularly favoured. The main exporting countries are Guatemala and Honduras, and the main importer is Europe. Data from World Wildlife Fund - Germany indicate that from January to March 1988, c. 6 million plants were exported from Guatemala, primarily to Germany and the Netherlands (Rauh 1992). These were a mixture of species, and included both wild-collected plants and plants produced by the developing local horticultural industry.

Chamaedorea palms and their products are used extensively in the floricultural and horticultural industries. Cut leaves of several species are a staple item in the florist trade of the U.S.A. and large quantities of leaves are also imported by Europe. Most of the leaves (both wild-collected and cultivated) appear to originate in Mexico, but some come from Guatemala, Honduras and Costa Rica. In 1986, an estimated nearly 360 million leaves were imported by the U.S.A. - 314,419,000 from Mexico, 40,179,000 from Guatemala and 4,145,000 from Costa Rica (Hodel 1992).

Prior to the 1950s, cycads (Zamiaceae: Ceratozamia, Dioon, Zamia) had been exploited in the region for their wood, for making laundry starch, alcohol, poison, fertilizer and various medicines, and as well for food. They are popular as ornamentals due to their beauty, rarity and toughness. Although many cycad species are exported by Mexico, countries such as Guatemala, Nicaragua, Costa Rica and Panama also have trade in their various native species (Jones 1993). Many of the Central American species are commercially exploited due to the proximity of the U.S. horticultural market. All cycads are regulated by CITES, which has encouraged their horticultural production.

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Factors causing loss of biodiversity

Central America has experienced alarming deforestation, especially since 1950. The region originally had extensive forests, mainly species-rich rain forests but also rich dry forests; about one-third of them remain. The causes of deforestation are numerous and vary somewhat from country to country (Nations and Leonard 1986; Leonard 1987; Utting 1991; Butterfield 1994).

Unsustainable agricultural and cattle-raising practices have resulted in previously productive land becoming unproductive, causing a demand for frontier land. In 1977, 10% of Central America was considered to be unproductive lands, but by 1987, 24% of the land area had become unproductive (Ypsilantis 1992). For example, the amount of land eroded or degraded seriously has reached 30% in Guatemala and 50% in El Salvador.

Much of the land deforested in the region has been converted in three stages: road construction, colonization and cattle-ranching. In the past few decades and years the pace of deforestation has accelerated, from the plains of the Petén in Guatemala to the Darién rain forest in Panama.

Road construction

Rain forests are being bulldozed to build roads for a variety of reasons, such as national development, military control and oil exploration (Leonard 1987), but mostly for logging commercially valuable timber (cf. MacKerron 1993). Unfortunately, even though only several prized species may be sought in an area, many other trees and the surrounding vegetation are affected during the logging operations. Areas also are cleared for feeder roads, staging and stacking, so the whole operation is quite destructive to the forest. After the loggers leave, the roads through the forest give access to poor farmers in search of land, who establish new settlements.

Colonization

Direct population growth is a factor that brings colonists into the rain forests. With the Central American population growing almost as fast as Africa's, farmers are clearing forest to grow basic food crops. Over the next 20 years, more than 90% of the region's population growth will take place in areas that presently are covered - or recently were covered - by rain forest (Nations 1987).

Roads into forest provide access for landless farmers to clear the forest to raise subsistence crops, such as maize, beans and manioc, as well as cash crops such as coffee, cacao and chili peppers. After 3-4 years of subsistence harvests, the soil is usually unproductive and farmers move on and repeat the cycle in areas newly disturbed. This shifting cultivation has more impact than it did a few generations ago, because with increasing populations the land is more extensively and intensively exploited, rather than being left to natural processes of recovery for many years. Some of the itinerant farmers seed their old plots with grasses and sell the plots to cattle ranchers, who consolidate them into large holdings.

The land in Central America is unequally distributed, which contributes to this second stage of forest loss. In 1975-1976, the 175,000 km² of farmland were 70% in large estates (of more than 200 ha) and 20% in medium-sized estates (10-200 ha), with just 10% of the area but 80% of the farms smaller than 10 ha (Heckadon 1992; cf. Leonard 1987). For example, the growing of bananas and cotton by major estates (including corporations) caused much conversion of forests in Guatemala, Honduras and Costa Rica.

Cattle production

Colonization often facilitates or leads to the third stage of tropical deforestation, which is expansion of commercial export crops into the rain-forest zone. The main factor in the elimination of Central America's tropical forests may be the raising of cattle. In the early decades, most of the forests along the Pacific coast were cleared by settlers to grow food crops and export products (e.g. cacao, indigo, coffee, bananas, cotton, sugar). With increased internal urban and export demand for beef from the 1960s and 1970s, rain forests on the Caribbean side were cleared and burned to establish pasturage. After 7-10 years, overgrazed pastures often turn into eroded wastelands, and ranchers must move to new areas. Cattle-ranching has thus contributed to the destruction of more than half of Central America's jungle since the 19th century, with most of the conversion taking place since 1950 (Nations and Komer 1984; Nations and Leonard 1986; Leonard 1987; Heckadon 1992).

Fuelwood

Gathering fuelwood also has caused serious forest degradation in certain countries in Central America. Most affected have been areas of high population density and agricultural areas in the Pacific coastal regions. Half of all the energy consumed in Central America comes from fuelwood, and the demand is increasing along with the number of small and medium-sized rural industries; less than 10% of the whole region's energy is produced hydroelectrically. Nearly three-quarters of the households use fuelwood, with the consumption per person c. 1 m³ each year (Heckadon 1992). In El Salvador, where 75% of the homes use fuelwood, gathering the wood constitutes the principal cause of forest degradation and deforestation (Utting 1991). With only 5% of its territory now forested, El Salvador has to import fuelwood from Honduras and Guatemala. Similar problems are occurring in Costa Rica, the most prosperous country in the region, where half the population still uses fuelwood. The same problem is arising in Guatemala (cf. Leonard 1987).

These several forces destructive to the tropical forests are causing major changes in land use. Two estimates of the recent extent of forest cover and deforestation are provided in Tables 36 and 37 (WRI, UNEP and UNDP 1994). The data in Table 36 are from the U.N. Food and Agriculture Organization's (FAO) Forest Resources Division, which defines total forest to consist of closed forest and open forest, including mixed forest/grassland with at least 10% tree cover and a continuous grass layer. The data in Table 37 are based on land-use data provided to FAO by national governments, and refer to closed, degraded and planted forest and woodland (but not cropland, e.g. with coffee or cacao). In Table 36 vs. Table 37, substantially larger amounts of forested land are estimated for Belize, Honduras and Nicaragua but somewhat smaller amounts for Costa Rica and Panama. According to data gathered by FAO and others (e.g. Collins 1990; Ypsilantis 1992), Central America's area in forest and woodland has decreased from c. 56% of the total land area in the first half of the 1960s to c. 33% in 1989-1991.

Tourism

Badly managed tourism has led to degradation of natural and cultural resources in Central America. Many protected areas that are not well managed are affected by constant pillaging from both local and foreign tourists. Throughout the region, one can observe the exploitation of bromeliads, orchids and ferns; in Belize, Honduras and Costa Rica coral-reef specimens are taken; in Guatemala and Belize archaeological objects are looted from National Parks. Tourism also has affected indigenous cultural practices, for example by influencing the design and colours of textiles and the items offered. In some cases the standard of living has increased in communities, but in others tourism has led to an increase in begging.

Most sites visited for their natural values do not have management plans, or evaluations of environmental impact or carrying capacity for visitors, which contributes to the ecosystems becoming highly altered. Nevertheless, there are programmes such as Mundo Maya (Maya World), Paseo Pantera (Path of the Panther) and specific management plans for some protected areas that are striving to diminish the negative impacts of tourism on the environment.

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Conservation

In recent years, the countries of Central America have agreed to several regional endeavours to help balance environmental concerns and development, with creation of a Comisión Centroamericana de Ambiente y Desarrollo (Central American Commission for Environment and Development) (CCAD) in 1989, which entered into effect 14/6/90, and was followed by a Central American Agenda on Environment and Development (1992, 26 pp.) and an Alianza para el Desarrollo Sostenible de Centroamérica (Alliance for Sustainable Development of Central America), 12/10/94 (13 pp.). The region also has agreed to a Convenio para la Conservación de la Biodiversidad y Protección de Areas Silvestres Prioritarias en América Central (Convention for the Conservation of Biodiversity and Protection of Priority Wild Areas in Central America), 1992. The Global Environment Facility (GEF) agreed in 1994 to provide an initial US$50 million to the Central American Environmental Fund in support of this Alliance.

Creation of protected areas

The origins of modern protected areas date from the 19th century and beginning of this century. Registrations began with establishment of the first municipal forests in 1870 in Guatemala - natural forests put under a special system of management for production of forest products - and with the creation of the first forestry laws in the region between 1905 and 1940 (Ugalde and Godoy 1993).

In 1923 Barro Colorado Island (15.4 km²), isolated as an island by the waters of the Panama Canal, was declared a biological reserve. In 1928 the colonial administration of British Honduras (Belize) declared Half Moon Cay (39 km²) a Crown Reserve. In 1939 some of the volcanic craters in Costa Rica were declared National Parks, which in the 1970s were ratified as protected areas. In Honduras in 1952 the Forest Reserve of San Juancito was declared, which in 1980 became La Tigra National Park (76 km²). In 1955 Guatemala declared its first ten National Parks, whereas 1958 marked the creation of the first National Park in Nicaragua.

In the 1970s, the first regional meetings to discuss the development of protected areas took place. During that decade agencies or institutions for the administration of National Parks were established. During the 1980s, ideas related to national systems of protected areas were developed as well as a regional system - the Central American System of Protected Areas (SICAP). The most significant changes toward strengthening the protected areas in the region began to take place during the 1980s.

In 1981 Belize passed its Law of Protected Areas. Between 1983 and 1985, Costa Rica strengthened its system by declaring refuges for wild fauna. During this same decade and the beginning of the 1990s, Honduras declared its most important protected areas, such as Río Plátano Biosphere Reserve (CPD Site MA15), Ríos de Cuero y Salado Wildlife Refuge (85 km²) and reserves for 37 cloud forests. El Salvador declared its first legally protected area in 1987 - Montecristo National Park (39 km²). In 1989 Guatemala proclaimed its Law of Protected Areas which in turn stimulated the creation of the two largest Biosphere Reserves in the country, Maya Biosphere Reserve and Sierra de las Minas BR (CPD Sites MA13 and MA14). Between 1980 and 1988, 14 of the 20 protected areas in Panama were declared.

Recently, an important factor in the creation of protected areas has been the inclusion in regional and national political agendas of the necessity to halt the general environmental degradation which is occurring and the severe loss of biodiversity. For example in October 1991, Nicaragua declared the two largest reserves in the country (SIAPAZ and Bosawas), equivalent to more than half the total area of the country's system of protected areas, and also declared more than 40 natural areas (IRENA 1993). In November 1991, Belize declared the National Parks of Chiquibul (c. 2659 km²) and Laughing Bird Cay (c. 14 km²).

Coverage in the system

Despite the fact that more than 300 conservation units and more than 91 proposed areas have been identified within the region, covering 100,000 km² and 19% of Central America, as of mid-1991 only 173 protected areas covering a little more than than 56,000 km² and 10.5% of the Central American territory were recognized under IUCN categories I-V of protected areas, for which there are management objectives emphasizing environmental preservation (WCMC 1992).

These 173 protected areas, plus the territory declared in the region that comprises 71 Forest Reserves, indigenous reserves, protected zones and areas of multiple use, bring the total to 244 declared units, covering c. 88,000 km² or 16.5% of the Central American region.

Panama, Nicaragua and Costa Rica have the most national territory under the highest protective categories of management (12-13%). Recent data indicate that the protected areas of Panama, Nicaragua and Guatemala make up 75% of the protected territory under SICAP. Nicaragua, for example, has 17,500 km² (14.7%) of its land surface in 71 protected areas that have been legally decreed (IRENA 1993). El Salvador and Belize are the countries with the least amount of land under SICAP (2.76%).

In addition to considering the amount of land designated for protected areas and the classification of the areas into categories of management objectives and use, it is essential to consider the effectiveness of administration and enforcement for protected areas. Although differing considerably, all the countries of Central America need to significantly augment their capacities to protect their designated areas (Barzetti 1993; Ugalde and Godoy 1993). For example, in Nicaragua 600 km² in protected areas are actively managed, 2500 km² are minimally managed, and 13,000 km² that are legally protected are without planning or management (IRENA 1993).

Gaps in coverage in the system

The majority of protected areas in the region have an emphasis on protecting mountain ecosystems (such as the peaks and volcanoes with cloud forests) and low tropical rain forests. Many areas of endemics and unique ecosystems are not well represented in SICAP. Examples are dry or semi-arid zones, humid mountain forests of cold altiplanos, zones with nearctic vegetation (oaks, pines, Liquidambar, etc.) and rare vegetation associations.

Consequently, many important additions need to be made to SICAP, including the following natural areas: the Maya Mountains in the south of Belize; in Guatemala, the region of Morazán in the semi-arid zone and the cold altiplano of the Cuchumatanes; in Honduras, the pine forests on Guanaja Island and the Tawahka Mountain Reserve zone; Los Morrales de Chalatenango in El Salvador; and the Arenal Cordillera in Costa Rica.

The protected areas located in the most populated zones of the region (mid-elevation plateaux and zones of the Pacific coastal plain) are the smallest and their biotopes the most threatened, because of the length of time human populations have been there and current social pressures. Urgent protection is needed for these small vegetational preserves to create areas which, through ecological restoration, will provide a return of the ecological goods and services required for wise development in these zones (e.g. north-western Costa Rica's Guanacaste Conservation Area - see Janzen 1986; Tenenbaum 1994).

Nicaragua and Guatemala offer the greatest potential within Central America for the creation of new units of conservation that would protect both ecosystems in the mountain zones and the lowland rain forest of the Atlantic coast. IRENA (1993) identified 1320 km² for the possible addition of protected areas in Nicaragua. Studies carried out in Costa Rica show the necessity to modify some of the boundaries of protected areas, with objectives (among others) of improving the representation of vegetation communities, enlarging key habitats, protecting endemic species and uniting strategic ecosystems (including remnants of natural resources, and incorporating marine resources).

Other ecosystems, such as mangrove swamps and humid coastal zones, need greater protection and more effective management throughout the region. National parks, such as Corcovado (CPD Site MA18) and Tortuguero in Costa Rica, have official marine portions that need better management.

The region lacks development in management and conservation of marine resources. Very few wetland coastal parks and marine parks exist - but there are the Ríos de Cuero y Salado refuge in Honduras (85 km²), Cayos Miskitos (c. 5027 km²) in Nicaragua, and Islas del Coco National Park (24 km²) and Caño Negro faunal refuge (c. 100 km²) in Costa Rica.

Suitable additions to the Central American system of coastal and marine protected areas are multiple bays and reefs through Belize; some areas of mangrove swamp in southern Belize; Punta de Manabique - La Graciosa and Manchón in Guatemala; Humedales de Caratasca, Laguna de Guaymoreto and Islas del Cisne in Honduras; Los Cóbanos in El Salvador; the Golfo de Fonseca as a tri-national micro-region of El Salvador, Honduras and Nicaragua; Río Grande de Matagalpa Delta, Tapamlaya and Kukulaya in Nicaragua; and Isla de Coiba in Panama.

The desirability of creating on frontier international borders both terrestrial and as well coastal marine protected areas has been recognized since 1974, but not until recent years have real interest and action been demonstrated. The best known projects include the establishment of La Amistad International Park between Costa Rica and Panama in 1982/1986 (CPD Site MA17); Trifinio or La Fraternidad Biosphere Reserve between Guatemala, El Salvador and Honduras in 1987; and the International System of Protected Areas for Peace (SIAPAZ) between Nicaragua and Costa Rica in 1989. These three areas plus the Gulf of Fonseca, the Gulf of Honduras and the Miskito Cays are six of the eleven areas given priority under the region's 1992 Convenio para la Conservación de la Biodiversidad y Protección de Areas Silvestres Prioritarias en América Central.

Many cooperative initiatives between Central American countries demonstrate the high priority being given to conserving natural resources. Examples include the Honduras and Nicaragua project for an ecological corridor of Río Plátano-Tawahka-Río Coco-Bosawas; the Guatemala and Belize project for the Chiquibul-Maya Mountain area; and the System of Protected Areas of the Gran Petén (SIAP) which includes Calakmul in Mexico, El Mirador-Río Azul in Guatemala and Río Bravo-Lamanai in Belize.

Centres of plant diversity and endemism

The Central American region has widely distributed plant species, and notable areas with high levels of endemism and diversity, eight of which are covered as Data Sheets (see Map 11 for their locations). Further research is likely to highlight some additional areas of major importance.

This overview is written by Luis Diego Gómez (Las Cruces Botanical Garden, P. O. Box 73, San Vito, Coto Brus, Costa Rica); Juan Carlos Godoy (IUCN Protected Areas and Biodiversity, Apdo. 112-I Zona 7, Guatemala City, Guatemala); Olga Herrera-MacBryde and Jane Villa-Lobos (Smithsonian Institution, Department of Botany, NHB-166, Washington, D.C. 20560, U.S.A.)

Guatemala

MA13. Petén Region and Maya Biosphere Reserve

MA14. Sierra de las Minas Region and Biosphere Reserve

Honduras

MA15. North-east Honduras and Río Plátano Biosphere Reserve

Costa Rica

MA16. Braulio Carrillo-La Selva Region

MA18. Osa Peninsula and Corcovado National Park

Costa Rica, Panama

MA17. La Amistad Biosphere Reserve

Panama

MA19. Cerro Azul-Cerro Jefe Region

MA20. Darién Province and Darién National Park

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