Tropical karstic forests These are limestone-based forests composed of primarily deciduous species with

seasonal flowering. They are only found on the ‘mogotes’

or haystack mountains of Cuba and Puerto Rico, the Cockpit Country and the John Crow Mountains in Jamaica, and on the Samana Peninsula of Hispaniola. Of these areas, only the Cuban mogotes have proven to support a noteworthy succulent flora. The mogote karstic forests have two evolutionary centres in Cuba with different floras, the oldest and richest (40 per cent endemic) in the western part of the island, and the youngest in central and eastern Cuba.

The western mogote forests occur on bare rocks of deeply eroded mountains and solitary cliffs consisting mainly of hard crystalline limestone. There is a single 4-9 m open canopy layer underneath which many smaller plants thrive thanks to the favourable light conditions.

Bombacopsis cubensis, a Cuban endemic tree with like trunk capable of water-storage, is present along with various species of Leptocereus with very restricted distribution patterns, including L. L. ekmanii, L. and L. prostratus. Other cactus genera occurring in this habitat are: Harrisia, Selenicereus, Opuntia, and is only found on the cliffs of the western mogotes. In the central and eastern karstic forests there is only one local species of Leptocereus, L. carinatus.

The most important areas where cacti and succulents occur in the West Indies are listed below in the section Priority Sites for Conservation.

Threats

Island floras are usually composed of ecologically restricted populations not capable of adapting to major environmental changes. The ability of the island communities to recuperate from external pressures is, in general, reduced. This characteristic makes them particularly vulnerable to degradation. There is a genetic reason for the vulnerability of island communities: the reduced gene pool from which the populations that the new biotopes are selected. This gene pool does not have the opportunity to improve over a long period of time.

The ‘island’ effect in the West Indian Archipelago is increased due to the fact that most of the larger island floras consist of groups of ancient, isolated floras (Borhidi 1991). As a consequence of isolation, the ecological tolerance and the genetic flexibility of populations decrease so that the competitiveness of species becomes low. Therefore, they cannot react satisfactorily to new environmental onslaughts, cannot take advantage of

A massive Dendrocereus tree more than 300 years old (diameter of trunk at base: 1.30 m),

Cuba. Vulnerable.

Bat-pollinated flower of Dendrocereus

succession, and cannot resist, or force back, new competitors. The vulnerability of the succulent endemic flora of the West Indies, in particular, is very pronounced because many have adapted to the extreme ecological conditions of oligotrophic or bare substrates.

Thus, the level of metabolism becomes low in these plants, and their competitiveness and degree of sociability diminish even more. On the other hand, it is quite likely that since Pleistocene times the formerly widespread xerophilous elements of the larger Caribbean Islands retreated to relict habitats: dry coastal or subcoastal areas, serpentines, and the slope

karsts. This was probably due to ch a

and cliffs of conical nges to a more humid climate.

The relict character of the succulent native flora of the West Indies another condition that increases vulnerability is indicated by the presence of relatively primitive, isolated (e.g. the dioecious Antillean group of Pereskia, Dendrocereus); the abundance of disjunct geographical distribution types, for example Dendrocereus nudiflorus, Bombacopsis cubensis, Furcraea

Opuntia nashii, and 0. millspaughii; and the large number of local represented by small populations, such as Opuntia hystrix, 0. militaris, 0. sanguinea, 0.

borinquensis, and Leptocereus spp. Consequently, the West Indian succulent flora is one of the most endangered plant communities in the world.

Clearing for agriculture The human population of the Caribbean Islands in 1991 was estimated to be 35 million (FAO projected to rise to about 40 million by the year 2000, and to nearly 60 million by 2025. In general, although all-island totals are increasing, the incremental rates and proportions of populations economically active in agriculture have fallen over the past decade. These

trends reflect increase in and efficiency on farms and in importation of foods replacing local produce, combined with migration to towns and coastal tourist resorts. Higher growth-rates are associated with larger rural populations and relatively smaller movements away from agricultural pursuits, as in Jamaica, Haiti, and

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the Dominican Republic. The total number of people comprising agricultural communities actually rose in Jamaica and Haiti (by 7.5 per cent) during the decade, this trend matching several of the poorer Central American republics where, however, numbers of those actually economically active on the land also fell.

Most agricultural development has been carried out on the seasonal evergreen forest or seasonal rain forest areas, and on lowlands formerly occupied by deciduous forest, which are not succulent-rich communities. Nevertheless, important coastal shrubwood areas in western Cuba with Dendrocereus and Pilosocereus robinii have been cleared for sisal sisalana and A. furcroydes) plantations. Traditional cassava, maize, and other small crop cultivation has also been attempted locally, with limited success, in many West Indian scrub areas.

Grazing The impact of drought-resistant cattle in the seasonally dry vegetation of the West Indies is well known. In the eastern lowlands of Cuba many stands of semi-deciduous xerophytic forests with Pereskia

and Harrisia sp. were cleared for grazing. Goats are usually grazed in the succulent-rich shrublands of south-eastern Cuba, north-western Haiti, and southern Dominican Republic. Opuntia caribaea which is considered a pest in Hispaniola, is one of the few native succulents that seems to benefit in overgrazed areas.

Burning The natural vegetation of the West Indian islands has not evolved the fire-tolerant life forms that are found throughout much of tropical Africa or continental America, so fire is comparatively more destructive in the Caribbean. Fire is commonly used to clear land for agriculture and settlements, to ‘clean’ undergrowth in forests and to encourage new growth in savannas and in the dry season for pasturage. Some of the arboreal Opuntia (subgenus Consolea), with thick-barked trunks, are more fire-tolerant than smaller cacti and can escape damage from fire to some degree, and so can Escobaria cubensis which in the dry season is at ground level or even below. But in general, burning is a major threat to the succulent plant flora. Particularly susceptible to fire damage are the thin-stemmed Harrisia spp. and most Melocactus spp. Harrisia portoricensis became extinct in the main island of Puerto Rico mainly because of fire;

now the species is confined to Mona and Monito Islands.

Opuntia borinquensis, which has not been seen in the wild for many years, is probably gone forever due to severe burning of the Cabo Rojo area in south-western Puerto Rico, some years ago. This place was considered an important regeneration area for Melocactus intortus in Puerto Rico; today very few individuals of this species can be seen there.

and tourism There are 16 urban centres in the Caribbean with over 100,000 inhabitants. These are

Cuba: Havana, Camaguey, Santiago de Cuba, Guantanamo; Dominican Republic: Santo Domingo, Santiago de Caballeros; Haiti: Port-au-Prince; Puerto Rico: San Juan; Jamaica: Kingston, Montego Bay;

Bahamas: Gran Bahama, Nassau; Guadeloupe:

P i t r e ; M a r t i n i q u e : Fort-de-France; Barbados:

Bridgetown; Trinidad: Port-of-Spain. Most of these centres are located in coastal areas.

Many restricted have suffered the location of an urban centre within their sites of occurrence.

Escobaria cubensis is facing the growth of the city of Holguin in eastern Cuba, and is dangerously retreating.

Borrichia and Leptocereus former occupants of the rocky coastal areas of Havana harbor and its environs, are nearly extinct now.

and Pilosocereus robinii are significantly reduced in occurrence by the urbanisation of north Havana province.

But these are not the only victims of the relatively

populous capital of Cuba; and

C. both endemic to the Havana city area, seem to have disappeared forever. They have not been seen in the wild for more than half a century.

Wildlife supported by succulents: endemic arboreal

rodent on columnar cactus

Cuba.

The growth of tourism in many of the islands over the past 50 years has resulted in hotel development along coastlines that have attractive sandy beaches. This has often meant a complete change to the landscape locally, involving the removal of natural vegetation and the planting of ornamental trees, shrubs, and grass for lawns and golf courses. Varadero Beach in Cuba and La touristic complex in the Dominican Republic are clear examples of this landscaping policy. The giant Dendrocereus in Varadero’s famous beach and resort area has been progressively replaced by Royal and other foreign flowering trees. The dioecious Pereskia quisqueyana, endemic to the Bayahibe beach and coastal lowlands in south-eastern Dominican Republic, is practically extinct by now; very few male individuals were left on the strand and as yet nobody has ever seen a female plant.

Mosquito control and marina developments have eliminated mangroves and littoral thickets in many places.

New roads have often been constructed to give access to coastal areas, and to connect cays with the mainland.

In some Caribbean islands the movement of people from rural areas to towns and resorts with the lure of employment opportunities in servicing the new tourism has coincided with the decline of export-based plantation agriculture. Increased demand for fresh fruit and vegetables has often resulted in unacceptable levels of cultivation on unsuitable land.

Mining and quarrying Threats to the landscape in the West Indies arise mostly from mining activities. Whatever type of mining is carried out, vegetation is cleared and there is always some surface disturbance either from stripping operations or dumping of tailings. The exploitation of bauxite in south-western Dominican Republic has had a significant impact on the dry shrubwoods of the Pedernales area. Quarrying for limestone in the haystack karstic mountains of north-eastern Puerto Rico and western Cuba has produced significant changes in local landscapes and strain on various species, notably Leptocereus leonii and L . scopulophilus.

Riversides and beaches are often exploited destructively for building sand and gravel and these removals may have secondary effects in the form of erosion, flooding, pollution, and loss of visual aesthetic.

Collecting for horticulture Some of the cacti and succulents of the Caribbean region are of considerable horticultural interest and some have been exploited to the detriment of wild populations. Undoubtedly, the most demanded genus is Melocactus. M. intortus has been heavily collected in Puerto Rico, for example (Martin and Farmer where hundreds of plants were formerly removed from the wild. It has also been exported in quantity from St. Eustatius and Grenada (Howard 1977).

Fortunately, M. intortus is the most widespread and abundant species of this genus in the West Indies.

Melocactus lemairei of Hispaniola, M. harlowii of eastern Cuba, and especially the ophiolitic dwellers M . matanzanus, M. actinacanthus, and M. guitartii were heavily collected in the according to local fashions in their respective countries of origin. Many people wanted rock gardens at that time. In Cuba the demand for M. actinacanthus led to the wholesale removal of nearly all the wild population; only a few dozen individuals can be seen nowadays in their original location, in very steep, nearly inaccessible cliffs.

The main Caribbean country involved in the export of cacti and other succulents for horticulture is the Dominican Republic. The bulk of the plants exported are non-indigenous, commonly cultivated Mexican cacti, and Euphorbia spp. Small quantities of indigenous cacti have, however, been exported including Opun tia an Harrisia divaricata, and Melocactus lemairei (Oldfield

1991). One large commercial outlet in the country exports mainly to the US.

Introduced species The introduction of the extremely aggressive shrub Dichrostachys cinerea from the savannas of Africa into Cuba and Marie has been an ecological disaster. The plant regenerates vigorously from the smallest root fragments. In south-central Cuba this invader has had a notable detrimental impact on Leptocereus arboreus and the xerophytic indigenous vegetation with which this species is associated.

On the small island of Guana in British Virgin Islands invasive succulent plants, originally introduced for horticultural purposes, include Sansevieria

Kalanchoe spp., and These pose a significant threat to the native flora and are now being controlled (Krauss 1991).

Local use The fruits of various species of Harrisia, P i l o s o c e r e u s ,

Selenicereus, Pereskia ta, and are used sporadically as sources of food in most West Indian islands, though none of them is In north-eastern Cuba a traditional red wine is made out of the ripe fruits of Opuntia The sticky mucilage from the stems of this species, mixed with slaked lime, is still in use in Cuba to make a coarse paint. Stenocereus is also used in Hispaniola, Cuba, and Jamaica as live fencing.

and other species are used for craft materials in Jamaica and other Caribbean islands. The saponin-rich juice extracted from the leaves of albescens and A. underwoodii serves locally as a laundry detergent in times of needs. It is not yet well known to what extent these uses have a detrimental impact on wild populations.

Natural environmental factors Hurricanes, volcanic eruptions, severe droughts, floods, and landslides are intrinsically associated with the West Indian environments, and may have profound effects on

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Dominican Repu

floras. On April 13, 1979, for example, the rare innesii seems to have been completely wiped out of the wild, when the area it inhabited in St. Vincent was devastated by the violent eruption of La Soufriere.

Conservation status

In general, it remains difficult to estimate population size and area of dispersal for rare plant species of the Caribbean Islands. Gaps in the flora coverage and the limited number of people with knowledge have restricted the availability of data on the conservation status of West Indian plants. Very preliminary and incomplete assessments of the cacti and other succulents have been made. Taxonomic uncertainties add to the difficulties of applying conservation categories. WCMC has records of over 100 Caribbean cacti in its Plants Database. Of these, about 40 are threatened on a world scale.

It has not been until now that a more realistic evaluation of the conservation status of the West Indian cacti has been attempted, and it provides the basis of a preparation of a systematic treatment of the Cactaceae for the New York Botanical Garden’s Flora of the Greater Antilles project. Based primarily on my field knowledge of the West Indian islands I have prepared the list of 243 succulent plant species in 16 families endemic to the West Indies (Table 3 of Annex 14). As noted above Aruba, Bonaire, Trinidad, Tobago, Margarita, and other small islands adjacent to Venezuela were excluded from the survey due to the fact that these territories are phytogeographically part of northern South America, and their flora predominantly continental. An appreciation of the current conservation status of each

is given by classifying them within four categories.

For some Haitian rare succulent species with very

limited distribution data and doubtful assessment information on which to base current conservation status, it is to carry out field surveys for more accurate field-based assessments of their conservation condition.

Priority sites for conservation

The West Indian endemic succulent flora occurs throughout the many islands of this dispersed archipelago.

Nearly every island, or group of islands, has its own local Rather than a few large protected areas, the coverage of such a disperse flora, in terms of conservation needs, requires a number of small-sized sites:

Cuba:

1) Coast and lowlands from Bay to