Sierra Madre del Sur
The Sierra Madre del Sur is a mountain range in southern Mexico, extending from southern Michoacán east through Guerrero, to the Isthmus of Tehuantepec in eastern Oaxaca. Geography. The Sierra Madre del Sur joins with the Eje Volcánico Transversal (Trans-Mexican Volcanic Belt) of central Mexico in northern Oaxaca, but is separated from this range further west by the valley of the Río Balsas and its tributary the Río Tepalcatepec. The mountains' highest point is Cerro Nube – , in southern Oaxaca, and just one major highway crosses the range between Acapulco and Mexico City. Although separated from  the main part of the Sierra Madre del Sur by the deep canyon of the lower Río Balsas, the mountains of southern Michoacán around Coalcomán are usually considered part of the Sierra Madre del Sur. Ecology. The range is noted for its very high biodiversity and large number of endemic species. The Sierra Madre del Sur pine-oak forests ecoregion occupies the higher reaches of the range. These forests are part of a chain of Mesoamerican pine-oak forests that stretch from the Southwestern United States to Costa Rica along the American Cordillera. Lower elevations of the range are covered  by tropical dry forests. Tropical dry forests include closed-canopy forests, woodlands, and thorn scrub, and many trees and shrubs lose their leaves during the winter dry season. The Jalisco dry forests ecoregion occupies the western end of the range's Pacific slope. The Southern Pacific dry forests occupy most of the Pacific slope of the range, from Michoacan in the west through Guerrero and Oaxaca. The basin of the Balsas River, north of the Sierra, is home to the Balsas dry forests. Protected areas. Protected areas in the Sierra include the Sierra de Manantlán, Zicuirán-Infiernillo, and Tehuacán-Cuicatlán  biosphere reserves, General Juan Álvarez National Park, Boquerón de Tonalá Flora and Fauna Protection Area, Omiltemi Ecological State Park, Los Olivos and El Nanchal state reserves, and the Campo Verde, Iliatenco, Cafetal San Juanito (Pluma Hidalgo), Cafetal Soconusco, Cerro Azul, Concepción Vista Hermosa, El Corozal, and El Borbollón, La Pandura y La Yerbabuena voluntary conservation areas.