Located approximately 260 miles south of Brownsville, Texas, the El Cielo Biosphere represents a unique series of environments. It is where neotropical and neoarctic fauna and flora meet. This is the central portion of the Sierra Madre Oriental where moisture laden winds from the Gulf of Mexico result in copious precipitation. A cloudforest exists at approximately the 1000-1500 meter elevation of the Sierra Madre Oriental. In the lowlands, or tierra caliente, the natural vegetation is tropical deciduous and riverine along the water courses.