The Paraguana xeric scrub (NT1313) is an ecoregion in Venezuela to the north and east of Lake Maracaibo and along the coast of Aruba, Bonaire, and Curaçao. The region holds flora and fauna adapted to the very dry conditions of the coastal dunes and inland areas of bush, scrub, briars and cacti. There are several endangered species of animals and birds. Efforts at protecting the environment have been ineffective. Most of the original trees have been cut down, dunes are being destabilized by loss of vegetation, scrub is replaced by farmland and vegetation is destroyed by grazing goats.
Geography
Location The Paraguana xeric scrub is in the northwest of Venezuela. It has an area of 1,605,792 hectares (3,968,000 acres). It extends along the Caribbean coast of the ABC islands (Leeward Antilles) to the east of the mouth of Lake Maracaibo and includes the Paraguaná Peninsula. A belt of the xeric scrub extends inland to the foothills of the Venezuelan Andes to the west of Barquisimeto. Along the Caribbean coast there are stretches of Amazon-Orinoco-Southern Caribbean mangroves. To the east the ecoregion merges into the Lara-Falcón dry forests ecoregion, and to the west merges into the Maracaibo dry forests ecoregion. In the south it meets the northeastern section of the Venezuelan Andes montane forests. The southeastern extreme of the ecoregion connects to the La Costa xeric shrublands.
Terrain The ecosystem includes the valleys of the Lara–Falcón depression in the coastal plains north of the foothills of the Venezuelan Andes, and the Paraguaná Peninsula. In the Pliocene epoch the peninsula was an island Paraguana has four marine terraces at 6 metres (20 ft), 15–20 metres (49–66 ft), 40–50 metres (130–160 ft) and 80 metres (260 ft) surrounding the Cerro Santa Ana inselberg. The 830 metres (2,720 ft) Cerro Santa Ana is the highest point in the hills of the center of the former island. The long, narrow and low Médanos Isthmus that joins Paraguana to the mainland was formed about 3,000 years ago by tectonic uplift. A 32 kilometres (20 mi) long ledge of exposed beach rock protects the eastern shore from strong wave action. The shoreline mainly consists of sandy or sand and silt beaches, with murky waters. Dunes have formed recently from sand that continues to arrive from the Gulf of Venezuela. The valleys of the Lara–Falcón depression contains ancient Quaternary rocks and recent sediments, and include plains and hills between the Andes and the Venezuelan Coastal Range. The soils are high in salt, mainly calcite. Soils are sandy along the coast and sandy with clay content further inland. The soils are all low in organic matter and phosphorus, and have pH close to neutral.
The Paraguaná peninsula has only intermittent streams. On the mainland the Mitare River divides into the Pedregal and Paraíso rivers, which empty into the gulf of Coro. The Tocuyo River, which crosses the Lara–Falcón dry forest ecoregion, is formed by the confluence of the Morere, Barigua and Bucares rivers. It empties into the Caribbean near the Triste Gulf. The Turbio River is the largest in the Lara Falcón depression.
Climate Annual rainfall on the Paraguaná Peninsula is usually less than 300 millimetres (12 in), while in the Lara–Falcón valleys it ranges from 350 millimetres (14 in) in dry areas to as much as 1,000 millimetres (39 in) in the foothills of the Andes. Ground-level temperatures may rise to 50 °C (122 °F) in the sun, but may fall to as low as 15 °C (59 °F) in the shade. The cause of the arid or semi-arid climate is unclear, but may be caused in part by the strong northeast trade winds blowing along the coast and by the contrast in thermal properties between the sea and the land. At a sample location at coordinates 10.75°N 70.25°W / 10.75; -70.25 the Köppen climate classification is "BSh": arid, steppe, hot arid. Mean monthly temperatures at this location range from 24.4 °C (75.9 °F) in January to 26.8 °C (80.2 °F) in August–September. Yearly total rainfall is about 680 millimetres (27 in). Monthly rainfall is 9.7 millimetres (0.38 in) in February, rising to 74.3 millimetres (2.93 in) in May, falling to 33.3 millimetres (1.31 in) in July and rising again to 141.9 millimetres (5.59 in) in October.
Ecology
The ecoregion is in the neotropical realm, in the deserts and xeric shrublands biome. The flora and fauna are adapted to extreme conditions of drought, salty soils, high winds and heat. Vegetation includes stunted scrub, low trees and cactuses. Herbaceous or bushy vegetation grows on the dunes and saline depressions by the coast. Further inland there is brush, scrub and areas of briars or cacti. These forms of vegetation may contain differing quantities of deciduous and evergreen trees depending on conditions, forming a complex mosaic of habitats.
Coastal grasslands The coastal grasslands include halophyte plants in salty depressions and dune vegetation that grows along narrow strips of stabilized dunes on the peninsula between Coro and Adícora, and along the mainland coast on either side of Coro. Other areas of mobile dunes have little or no vegetation. Halophyte grasslands are typically low and open, without trees or bushes. Species include Atriplex pentandra, Heterostachya ritteriana, Salicornia fruticosa, Batis maritima and Sesuvium portulacastrum. Grasslands on the sand dunes include dense but uneven herbaceous-bushy flora. Species include Scaevola plumieri, Portulaca pilosa, Cakile lanceolata, Cyperus planifolius, Sporobolus virginicus, Sporobolus piramydatus, Ipomoea pes-caprae, Euphorbia buxifolia, Spartina patens, Lycium bridgesii, Calotropis procera, Egletes prostrata, Argusia gnaphalodes, Tournefortia volubilis, Opuntia caracasana, Heterostachys ritteriana, Chamaesyce dioica, Chamaesyce mesembryanthemifolia, Croton punctatus, Cenchrus echinatus and Tribulus zeyheri. Isolated dunes may hold windblown trees and bushes such as Conocarpus erectus, Prosopis juliflora and Vachellia tortuosa.
Inland regions
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