Extending from northwest to southeast through Mexico from the U. The terrain ranges from permanently snow-covered peaks to hot, tropical valleys; and from the humid, thickly vegetated seaward slopes to the dry, largely barren interior-facing slopes. Agricultural products vary according to the climate. Lumbering is done in the N Sierra Madre Occidental.
The change of air pressure in northwestern Mexico and the southwest US is considered the major cause of seasonal variation. The mountain has a mild climate with summer temperatures maintained at constant levels. Precipitation also varies with the annual differences associated with El Nino -Southern Oscillation. The Sierra Madre Occidental creates different sets of condition that are favorable for a wide variety of flora and fauna.
The pine-oak forests found at an elevation of approximately 4, to 9, feet throughout the range has high biodiversity and endemism. The dominant plant species vary across the range, varying from scattered woodland to coniferous and deciduous forests. Although the range did experience extensive volcanism in the past, which also deposited substantial amounts of gold and silver in the area, most of these volcanoes are either dormant or extinct.
The climate, and, thus, the ecology of the Sierra Madre Occidental depends greatly on location in this north to south mountain range. There are also large seasonal variations in temperature and moisture in the region due to its proximity to both the Atlantic and Pacific Oceans.
Within the Sierra Madre Occidental, there is a wet summer monsoon season as well as a relatively dry winter season. The southern part of the range receives considerably more rainfall than the northern parts, often due to the presence of tropical storms. Much of the range is covered by the Sierra Madre Occidental pine-oak forests ecoregion, which covers an area of about , square km 86, sq. This ecoregion is an amalgamation of different ecosystems.
At lower elevations, it is dominated by very hot, dry deserts and xeric shrublands as well as tropical dry forests. The Sonoran Desert is located to the northwest of the range and extends partly into its lowest and westernmost regions. Meanwhile, the Chihuahuan desert is located to the northeast of the range, and covers part of its lowlands.
The mid elevations of the peaks in the Sierra Madre Occidental are home to a mix of oak wooded grasslands and pine-oak forests. There are dozens of species of conifers and deciduous trees in the range, some of which are endemic to the region.
Additionally, the range contains over bird species, some of which are endangered, such as the thick-billed parrot and the military macaw. The basin of the Balsas River, north of the Sierra, is home to the Balsas dry forests.
The range runs northwest-southeast from the state of Chiapas in Mexico, across western Guatemala, into El Salvador and Honduras. The range forms the main drainage divide between the Pacific and Atlantic river systems.
On the Pacific side the distance to the sea is short, and the streams, while very numerous, are consequently small and rapid. On the eastern side, a number of the rivers of the Atlantic slopes attain a considerable volume and size.
The base of many of the volcanic igneous peaks rests among the southern foothills in the southern region of the range. By The Editor. Share on Facebook Share on Twitter Share through email. Sierra Madre Mountain System The Sierra Madre Mountain System is part of the American Cordillera, a chain of mountain ranges cordillera that consists of an almost continuous sequence of ranges.
Sierra Madre de Oaxaca The Sierra Madre de Oaxaca mountain range is located in southern Mexico, primarily in the state of Oaxaca, extending north into the states of Puebla and Veracruz. All Rights Reserved. Subfooter menu.
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