Venezuelan Ecosystems

Cloud Forest

Popular but somewhat ambiguous term that refers to any very humid or wet mountain forest that is frequently enveloped in clouds and whose trees are heavily burdened with mosses and epiphytes. Most pre-montane and montane wet forests (below) are, in a popular sense, cloud forest.

Venezuelan Habitats

Tropical Wet Forest

Matur

e canopied, tall, and evergreen forest of lowland areas with rainfall near or in excess 0f 4000mm/yr Confined to a few small regions in Amazonas and Bolivar. Includes tropical rain forest, a term not used here because of ambiguity in popular usage.

Dry Forest

Low to moderately high, deciduous forest in which the dry season is marked and severe. Most trees lose their leaves for up to half the year Rainfall averages ca. 500—l000mm/yr and falls during a few "wet“ months of the year. Examples: Morrocoy National Park; locally west of El Palmar; and vicinity of Guasipati, Bolivar. Usually prefaced in text as tropical dry forest or montane dry forest depending on elevation in which it occurs.

Moist Forest

Slightly drier forest than previous categories. Moderate height, semi-evergreen forest in which many trees are deciduous and vines become more numerous. Transitional between evergreen humid forest and deciduous dry forest. Rainfall ca. 1000-2000mm/yr Foothills above Ocumare de La Costa on north slope of Coastal Cordillera; west of El Palmar; and vicinity of Guasipati, Bolivar Usually prefaced in text as tropical moist forest or premontane moist forest.

Humid Forest

Tall, canopied, and largely evergreen forest. Resembles tropical wet forest but rainfall lower than 2000-4000mm/yr in the lowlands, less in the highlands. There is usually a moderate dry season and a longer wet season. This is the dominant lowland forest south of the Orinoco. Also found in foothill and montane zones in the Andes and northern cordilleras. Usually prefaced in text as tropical humid forest, premontane humid forest, or montane humid forest.

Desert Scrub or Arid Scrub

Permanent scrub zone that occupies much of Caribbean littoral and locally inland in rain-shadow valleys in mountains (eg., Rio Chama, Merida). Rainfall ca. 400-700mm/yr or less and falls only during a few months. Characterized by low thorny bushes, small drought-resistant trees, and several kinds of cactus.

Pre-montane Wet Forest

Specific designation for wet forest found at low elevations in mountain areas. Elevational limits vary but are mostly ca. 1000—l600m, rarely as low as 400m. Rainfall is high; the forest is fre-quently enveloped in clouds, especially in the afternoon; and trees carry abundant loads of epiphytic plants, including mosses and orchids. In popular terminology this and montane wet forest are often called "cloud forest."

Terra Firme Forest

Humid or wet lowland forests not subject to inundation. The designation is applied mainly to lowland forests of the Amazonian and Orinocan region to distinguish them from varzea forest.

River-edge Forest

Zone of Cecropic, Erythrina, Hcus, and vines along the banks of the Orinoco, Caura, etc.

May or may not flood seasonally

Várzea Forest

Humid or wet lowland forest that is seasonally flooded to depths of ca. l-6m, often for several months, one or more times a year Found in floodplains of major rivers and their tributaries, including one (or occasionally both) banks of the Rios Negro, Casiquiare, Orinoco, Caura, and Cano Colorado. Most gallery forests (below) in the llanos flood for several months each year but they are not comparable to these tall, floristically complex vérzea forests of south of the Orinoco.

Paramo

Wet to moderately dry tropical alpine grassland or shrubland that occurs from treeline (ca.3000-3300m) to the upper limit of vegetation or snowline. Characterized by large expanses of bunch grass mixed with rosette—shaped Espeletia shrubs of the Compositae family Quaking bogs and cold lakes dot poorly drained regions of the paramo. Rainfall in the paramo is highly

seasonal in Venezuela, with a spectacular display of flowering from September to November.

Sandy-belt Forest

Humid forest growing on white sandy soil. Resembles terra Erme forest but is less luxuriant, usually having a lower canopy and con-

taining a high proportion of trees with tannins, phenols, and strong defensive chemicals in their leaves. Rivers flowing through sandy-belt forest are always black. Vast areas of sandy-belt forest are found in-the upper Orinoco and upper Rio Negro drainage of Amazonas, as well as spottily throughout much of Bolivar: A few

sandy-belt forests are subject to seasonal inundation, then usually resembling a dense, stunted, and low-stature scrubiorest. 4 _ .

Montane Wet Forest

Specific designation for wet forest found at middle or upper elevations in mountain areas. Elevational limits vary but are mostly ca.1600-3000m. Abundant rainfall and foggy conditions prevail. Trees are tall at middle elevations, shorter in stature at high elevations, and always heavily festooned with mosses and epi-phytes. Along with premontane wet forest, often

called "cloud forest” in popular terminology

Savanna Woodland

Resembles sandy-belt forest but is scrubbien V shorter (about 3-5m), and more open. ln its, extreme form resembles Brazilian cerrado, with short, well-spaced shrublike trees and a low semiclosed canopy In appearance intermediate between sandy-belt forest and savanna.

Elfin Forest (Dwarf Forest) & Elfin Woodland

Elfin forest is a stunted or dwarf forest growing at high elevations, typically near tree line and often where exposed, as on ridges or slopes. Formed under constant exposure to wind and fog and is characteristically gnarled, mossy and miniature in size (ca. 2-Sm high). Elfin woodland is similar but refers to vegetation where

the trees and shrubs are more widely spaced.

Light Woodland and Thinned`Woodland

These habitats include parklike areas. They are forests thinned by human activity (e.g., for coffee plantations or by lumbering) where a more or less continuous canopy is maintained but much undergrowth is removed. Important habitats for wintering North American migrants.

Gallery Forest and Riparian Woodland

These are more or less interchangeable terms for bands of trees confined to and dependent on watercourses in otherwise largely open or shrubby country They border virtually all rivers in the llanos (unless removed by people).

Melastome-dominated Forest

Highly characteristic, mostly regrowth vegetation stage found at middle elevations on tepuis. Mostly low to moderately high (to ca. 15m) and dominated by dense stands of various species of Melastomataceae. Widespread in disturbed areas along the highway ascending Sierra de Lema, Bolivar

Second-growth Woodland (Re-growth Woodland)

Relatively advanced re-growth stage of forest that in time will become mature forest. Differs from mature forest in species composition, absence of emergent trees, usually lower canopy height, and more open canopy (older stages largely

closed) with well-lighted, bushy undergrowth.

Forest or Woodland Border

Edge of a forest or woodland along a road, stream, treefall, etc., and usually dense and shrubby Older stages become a solid wall of vegetation. Common plants include Cecropia, Heliconia, Miconia, Piper, and vines. This is the most frequently "birded" habitat in most tropical areas, and it usually contains a mixture of both forest and nonforest bird species.

Shrubby Areas and Clearings

Any re-growth vegetation, with or without scattered trees, that follows deforestation and precedes woodland. Mostly composed of shrubs, thickets, grass, and small trees. Later stages give way to large trees.

Scrubby Areas

Relatively permanent plant community (not a re-growth stage) found chiefly in drier regions. Characterized by scrubby bushes and small trees, often Acacia. In some cases forested areas become so permanently altered as a result of human activity (erosion, overgrazing, wood-cutting, etc.) that forest regeneration is unlikely and they become scrubby areas.

Scrubby Areas

Relatively permanent plant community (not a re-growth stage) found chiefly in drier regions. Characterized by scrubby bushes and small trees, often Acacia. In some cases forested areas become so permanently altered as a result of human activity (erosion, overgrazing, wood-cutting, etc.) that forest regeneration is unlikely and they become scrubby areas.

High Tepui Shrub Woodland

Scrubby mixture of herbs, grass, and dense leathery-leafed shrub vegetation peculiar to upper elevations of most tepui mountains.

Composed mostly of highly range-restricted, endemic plants. Specific plant associations are often unique to each major tepui.

Marshes and Swamps

Areas with more or less permanent standing water dominated by various kinds of grasses, sedges, and non-woody emergent vegetation, but not trees. Fresh or brackish water. Wide-

spread in llanos. ln forested areas found mainly

around oxbow lagoons, rivers mouths, and on

river islands.

Mangroves

Forest community of a few species of ever, green trees and shrubs that grow in salt or brackish water of the, tidal zone. Several

species of mangroves are characterized by winy dark green foliage and a tangle of aerial or stiltlike roots. Locally distributed along the coast. Largest expanses in Venezuela occur in the Orinoco Delta.

Coastal, Offshore, and Pelagic Zones

These habitats are, respectively within sight of land, beyond sight of land but over the continental shelf, and open ocean beyond the continental shelf.

Savanna or Grassland

Savanna is a general term for grass.land, although the word grassland is sometimes reserved for areas lacking shrubsor trees, while savanna isreserved for areas with shrubs or A trees. They are used interchangably here, and often grade-into.open*savaiina woodland f g (above), especially in whtté sandy·sql`,areas.'

V The‘Venezuelan-Colon1bian‘·llan‘os_gisthe largest grassland in northern SOL1§h'·AlTlQlflC&

Morichales

Areas dominated almost exclusively by moriche palms (Mauritia). Found in savanna or forest but always where the soil is poorly

drained, wet, and/or permanently water- , logged. Palms often grow in shallow water A grove of these palms is known in Spanish as a morichal and represents a specialized kind of swamp forest.