Loma El León Natural Monument is located in Lara State, on the outskirts of the expanding urban area of Barquisimeto (Iribarren Municipality), to the southwest of the Juan de Villegas Parrish. This protected area lies along the left bank of the Turbio River, runs into the valleys of the Lara-Falcón Depression, and covers the area of transition between the Andes Mountains and the Coastal Mountains (MARNR, 1992; WWF, 2001). The highest point is Loma El León, with an altitude of 1,300 m above sea level (ASL) (Smith & Rivero 1983), which dominates the valley of the Turbio River and offers an impressive view of the city of Barquisimeto (MARNR, 1992).
Loma El León is found in the arid zone of Lara State, an ecosystem where scarce rainfall limits the amount of surface water and conditions the development of vegetation. The zone is abundant in species able to tolerate long periods of drought (Ferrer, 1985). The powerful, steady, dry winds that blow across the length of the coastal plain also impact the ecosystem (WWF, 2001). The average annual precipitation (measured at a station near the summit of Loma El León) is 580 mm and follows a bimodal pattern with two peak seasons: one from April through May and one from November through December. However, the denser vegetation seen on the southeastern slopes signals the presence of higher amounts of precipitation. The imbalance between precipitation and evapotranspiration, combined with below-average precipitation levels, produces arid soils for the majority of the year. The most pronounced drought conditions tend to occur between January and March. The annual average temperature is 23°C, with a minimum of 15°C in the highest zones (Smith & Rivero, 1983).
Precipitation events tend to be associated with the formation of intermittent streams, which are able to generate sudden floods. Such variations in surface flow are caused by the limited vegetative cover and the low permeability of the soils. Surface runoff tends to dominate the process of infiltration. The limited water infiltration then produces dry soils and little aquifer recharge. This scenario is typical of the “wadies” class of hydrographic basins that are found in dry regions (Ferrer,1985). Extreme precipitation events are very infrequent: days with more than 10mm of rainfall only occur approximately 12 days a year (Smith & Rivero, 1983).
In Loma El León, the Morán or Loma El León formation of the Tertiary (Paleocene-Eocene) crops out. This formation is characterized by a sequence of sedimentary rocks deposited in marine environments, and includes shales, sandstone, and minor veins of limestone. In the shales, foraminifer fossils (fossils of marine microorganisms that have a calcareous shell, with openings where pseudopods protrude) are commonly found (PDVSA-Intevep, 2005). In Loma El León, the natural lithology of the hills (which are principally quartzite) does not favor erosive processes. For this reason, slopes remain relatively stable and caves are rare (Smith & Rivero, 1983).
The soils of the ecoregion, which are sandy to loamy or clayey, are very poor in organic material, have a neutral pH, a low phosphorous content, and changeable metallic base concentrations (Alacrón, 1990).
Satellite image of Loma El León Natural Monument showing western sectors of Barquisimeto (Source: Modified from GoogleTM Earth 2005)