V

The islands of the southern Caribbean are home to two species of Melocactus with restricted distributions: M. macracanthos (Dutch Antilles, probably not at risk) and M. broadwayi (Tobago, Grenada, and St Vincent, status unknown).

The Galapagos islands, which have protected status as an Ecuadorian National Park, are home to Talinum and about seven rare, endemic cactus species, comprising two endemic monotypic genera (Brachycereus, Jasminocereus) and the remarkable, giant tree opuntias. Recent fires on Isabella Island have been cause for concern and pressure from tourism is increasing, though to what extent these are affecting xeric habitats is not clear. Fortunately, attention from conservationists is currently being focused on the archipelago (Jervis 1994).

The Andean Region

This is the most important area for succulent plant genera and species in South America, most of the species and many of the genera being endemic. Habitats including succulents are very diverse, ranging from coastal fog desert, where rainfall is almost non-existent, to humid forest, seasonal dry forest and dry alpine vegetation, such as the paramos of the northern Andes and the Puna of Argentina, where some succulents occur at elevations in excess of 4000 m. Unfortunately there are insufficient data concerning some of the areas of greatest diversity in this region (especially Peru), but it seems probable that taxa occurring in regions above 2500 m are generally in less danger than those from lower elevations, where human influence is strongest. However, in parts of the central Andes at high elevations continually expanding primitive agriculture and over-grazing are substantially modifying some ecosystems and almost certainly leading to the endangerment of endemic species.

The Andean Region and those which follow are treated mainly on a country-by-country basis:

Columbia and Venezuela

The part of the northern Andes which falls within the territories of Colombia and Venezuela is not very rich in succulent plant taxa, but there are 2 endemic Melocactus spp. (Taylor 1991b), about 7 endemic Echeveria (c. 4 spp. are awaiting formal description, Taylor and Eggli, ined.), and at least 2 Agave spp. Of these endemic taxa, only 2 (Echeveria recurvata s. 1 .,E. venezuelensis) are known to be widespread, but most of the remainder, although they may be rare and lacking any kind of habitat protection, are not known to be under particular threat in the dry, precipitous environments they mostly inhabit. An exception is Melocactus schatzlii, which occurs at relatively low elevations in habitats near to roads and villages in the Rio Chama valley, south-west of Merida (Venezuela), and to the south of Bucaramanga (Colombia).

Melocactus schatzlii, Rare endemic of two valleys, one in north-west Venezuela, the other in northern Colombia.

Table 3.19 Distributional information for succulents at species level, by region of Peru

(Source: Brako and Zarucchi 1993)

Region of Peru Altitudinal range (m) Species Per cent total

Endemics

Amazonian

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