- Madrean pine-oak woodlands
The Madrean pine-oak woodlands are
subtropical woodland s found in the mountains ofMexico and the southwesternUnited States .The Madrean pine-oak woodlands are found at higher elevations in Mexico's major mountain ranges, the
Sierra Madre Occidental , theSierra Madre Oriental , theTrans-Mexican volcanic belt , theSierra Madre del Sur , theSierra Madre de Oaxaca , and thePeninsular Ranges of theBaja California Peninsula . Enclaves of pine-oak woodland are also found on mountaintops in southernArizona andNew Mexico and in westernTexas , where they are known as theMadrean sky islands .Conservation International estimates the woodlands' original area at 461,265 km². The woodlands are surrounded at lower elevations by otherecoregion s, mostly tropical and subtropicaldeserts and xeric shrublands ,forest s, andgrassland s.The pine-oak woodlands are made up of stands of
oak "(Quercus)",pine "(Pinus)",douglas-fir "(Pseudotsuga)" andfir "(Abies)". The trees generally occur in mixed stands, though monospecific stands are sometimes found. The pine-oak woodlands are home to one-quarter of Mexico's plant species, and Mexico is home to 44 of the 110 species of pine and over 135 species of oak, over 30 percent of the world’s oak species. Plant species derived from Madrean ancestors, known as theMadro-Tertiary flora , are an important element of theCalifornia chaparral and woodlands ecoregion.The
World Wildlife Fund recognizes several distinct pine-oak woodlands ecoregions, based on geographic distribution and species mix.
*Sierra Juarez and San Pedro Martir pine-oak forests of theSierra Juárez andSierra San Pedro Mártir ranges of the northern Baja California peninsula.
*Sierra de la Laguna pine-oak forests of theSierra de la Laguna in the southern Baja California peninsula.
*Sierra Madre Occidental pine-oak forests extend along the Sierra Madre Occidental range from theRio Grande de Santiago in Mexico'sJalisco state throughNayarit ,Sinaloa ,Durango ,Sonora , andChihuahua , and include the Madrean Sky Islands of Arizona and New Mexico.
*Sierra Madre Oriental pine-oak forests extend along the Sierra Madre Oriental ranges of Texas and Mexico, from mountaintop enclaves in westTexas throughCoahuila ,Tamaulipas ,Nuevo León ,San Luis Potosí ,Queretaro andGuanajuato .
*Trans-Mexican Volcanic Belt pine-oak forests
*Sierra Madre del Sur pine-oak forests
*Sierra Madre de Oaxaca pine-oak forests External links
* [http://www.biodiversityhotspots.org/xp/Hotspots/pine_oak/ Madrean Pine-Oak Woodlands (Conservation International)]
* [http://worldwildlife.org/wildworld/profiles/terrestrial/na/na0526_full.html Sierra Juarez and San Pedro Martir pine-oak forests (World Wildlife Fund)]
* [http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt0307_full.html Sierra de la Laguna pine-oak forests (World Wildlife Fund)]
* [http://www.worldwildlife.org/wildworld/profiles/terrestrial/na/na0302_full.html Sierra Madre Occidental pine-oak woodlands (World Wildlife Fund)]
* [http://www.worldwildlife.org/wildworld/profiles/terrestrial/na/na0303_full.html Sierra Madre Oriental pine-oak forests (World Wildlife Fund)]
* [http://www.cas.vanderbilt.edu/bioimages/ecoregions/50302frame.htm Sierra Madre Occidental Pine-Oak Forests images at bioimages.vanderbilt.edu] ( [http://www.cas.vanderbilt.edu/bioimages/ecoregions/50302.htm slow modem version] )
* [http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt0310_full.html Trans-Mexican Volcanic Belt pine-oak forests (World Wildlife Fund)]
* [http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt0309_full.html Sierra Madre del Sur pine-oak forests (World Wildlife Fund)]
* [http://www.worldwildlife.org/wildworld/profiles/terrestrial/nt/nt0308_full.html Sierra Madre de Oaxaca pine-oak forests (World Wildlife Fund)]
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