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The Sierra Madre de Oaxaca pine-oak forests is an ecoregion of southern Mexico. It occupies the Sierra Madre de Oaxaca, which lies mostly within the state of Oaxaca, extending north into Puebla and Veracruz states. It is one of a chain of pine-oak forest ecoregions extending along the American Cordillera from Arizona and Baja California in the north to Nicaragua in the south.

The ecoregion covers an area of 14,300 square kilometers (5,500 square miles), lying above 1600 meters elevation. The Sierra Madre de Oaxaca runs northeast-southwest, extending 300 kilometers from Pico de Orizaba in the northeast to extends to the Isthmus of Tehuantepec in the southeast. Peaks in the Sierra Madre de Oaxaca average 2,500 meters in elevation, with some peaks exceeding 3,000 meters. The Gulf Coastal Plain lies to the east, and a series of river valleys separate the Sierra Madre de Oaxaca from the Sierra Madre del Sur to the southwest and the Trans-Mexican Volcanic Belt to the northwest. The range intercepts humid air moving west from the Gulf of Mexico, and the ecoregion is bounded on the east by the humid Oaxacan montane forests, which lie below 1600 meters elevation. To the east, the xeric Tehuacan Valley matorral occupies the Tehuacan valley to the northwest, the Jalisco dry forests occupy the upper basin of the Santo Domingo River, which lies in the rain shadow of the Sierra, and the Southern Pacific dry forests lie to the south along the Pacific coast, extending into the upper basin of the Tehuantepec River and the Valley of Oaxaca. The dry forests separate the Sierra Madre de Oaxaca pine-oak forests from the Sierra Madre del Sur pine-oak forests to the southwest.

The vegetation varies with elevation and exposure. The predominant vegetation types are pine forest, pine-oak forest, oak forest, and cloud forest.

• Sierra Madre de Oaxaca pine-oak forests (World Wildlife Fund)