| 词条 | Madrean pine-oak woodlands |
| 释义 |
The Madrean pine-oak woodlands is an ecoregion of the Tropical and subtropical coniferous forests biome, located in North America. They are subtropical woodlands found in the mountains of Mexico and the southwestern United States. Conservation International estimates the woodlands' original area at 461,265 km². The woodlands are surrounded at lower elevations by other ecoregions, mostly tropical and subtropical deserts and xeric shrublands, forests, and grasslands. Woodland areas were isolated from one another and from the pine-oak woodlands of the Sierra Madre Occidental to the south by the warming and drying of the climate since the 1st century CE. DistributionMexicoThe Madrean pine-oak woodlands are found at higher elevations in Mexico's major mountain ranges, the Sierra Madre Occidental, the Sierra Madre Oriental, the Trans-Mexican volcanic belt, the Sierra Madre del Sur, the Sierra Madre de Oaxaca, the Peninsular Ranges of the Baja California Peninsula. Madrean sky islandsThere are also approximately 27 enclaves in southern Arizona and New Mexico and in western Texas, where they are known as the "Madrean sky islands". The major Madrean "sky island" ranges in Arizona are the Dragoon Mountains, Chiricahua Mountains, Pinaleño Mountains, Santa Catalina Mountains, Rincon Mountains, Santa Rita Mountains, and Tumacacori Highlands. In New Mexico, the Sacramento Mountains and Guadalupe Mountains, which extend into Texas, as well as the Davis Mountains and Chisos Mountains, are also forested Madrean sky islands. FloraThe pine-oak woodlands are composed of stands of oak (Quercus), pine (Pinus), douglas-fir (Pseudotsuga) and fir (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 28% of the world's oak species. Plant species descended from Madro-Tertiary flora, Madrean ancestor species, are an important element of the California chaparral and woodlands ecoregion. Madrean pine-oak woodlands sub-ecoregionsThe World Wildlife Fund recognizes several distinct Madrean pine-oak woodlands sub−ecoregions, based on geographic distribution and species mix. They include:
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26 : Tropical and subtropical coniferous forests|Ecoregions of Mexico|Madrean Region|Madrean Sky Islands mountain ranges|Flora of Mexico|Forests of Mexico|Montane forests|Flora of Baja California|Flora of Central Mexico|Flora of Northeastern Mexico|Flora of Northwestern Mexico|Flora of Southwestern Mexico|Flora of Southern Mexico|Sierra Madre de Chiapas|Sierra Madre de Oaxaca|Sierra Madre del Sur|Sierra Madre Occidental|Sierra Madre Oriental|Trans-Mexican Volcanic Belt|Natural history of the Peninsular Ranges|Tropical and subtropical coniferous forests of the United States|Ecoregions of the United States|Flora of Arizona|Flora of New Mexico|Nearctic ecoregions|Neotropic ecoregions |
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