Sierra Madre Oriental & Occidental Pine-Oak Forests

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Sierra Madre Occidental, Chihuahua, Mexico.
© WWF-Canon / Edward PARKER

About the Area

This Global ecoregion is made up of 3 terrestrial ecoregions: Sierra Madre Occidental pine-oak forests; Sierra de la Laguna pine-oak forests; and Sierra Madre Oriental pine-oak forests.

Consisting of numerous mountain peaks and ridges that extend from just over the border in the southwestern United States into Central Mexico, this ecoregion supports a vast array of plant and animal species; many of which are restricted to single peaks or ranges.

Among these species are some important wild relatives of agricultural crops, such as Agave (Agave spp.).

The Cape Region of the Baja California peninsula includes 3 extremely fragile and valuable ecoregions: Sierra de la Laguna dry forests, Sierra de la Laguna pine-oak forests, and San Lucan xeric scrub.

Size:
289,000 sq. km (112,000 sq. miles)

Habitat type:
Tropical and Subtropical Coniferous Forests

Geographic Location:
North America - Southwestern United States and Central Mexico

Conservation Status:
Critical/Endangered

Local Species
The most speciose plant families represent Asteraceae, Fabaceae, Poaceae and Euphorbiaceae. In total, 12 species of oak trees are found within these conifer forests.

Together these plants support an impressive array of bird species including the Mexican jay (Aphelocoma ultramarina), Mexican chickadee (Parus sclateri), zone-tailed hawk (Buteo albonotatus), maroon-fronted parrots (Rhynchopsitta terrisi), thick-billed parrots (R. pachyrhyncha), Strickland's woodpecker (Picoides stricklandi), and Montezuma quail (Cyrtonyx montezumae). Predators with large ranges, such as Gray wolf (Canis lupis) and Jaguar (Panthera onca) frequent these habitats as well.

The Sierra Madre Occidental pine oak forests are rich in endemic and endangered plant and animal species including over 85 species of reptiles (of which 22 are endemic), 20 amphibians (12 of them endemic), and a number of endemic birds, as well. In the northern portion, over 15 species of pine trees and more than 25 types of oaks occur. The 27 species of conifer trees and 21 oak species recorded in these mountains, make them a center of diversity for these groups of trees. More than 300 species of birds make their homes here, including the golden eagle, endangered thick-billed parrot, military macaw, and tufted jay.
 / ©: WWF-Canon / John S. MITCHELL
Golden eagle (Aquila chrysaetos).
© WWF-Canon / John S. MITCHELL

Featured Species

The Mexican Chickadee, Parus sclateri or Poecile sclateri, is a small songbird with a black cap, white cheeks, and a short black bill. Their backs and flanks are gray and they have paler grayish underparts. The Mexican Chickadee has a long black bib, which extends from its chin down onto its upper breast. A whitish band below the bib extends down the center of the belly. The typical adult wingspan is 18 cm, and their overall length is 13 cm.

Although primarily nonmigratory, Mexican Chickadees sometimes fly to lower elevations during the cold of winter. The Mexican Chickadee's song is distinct from other chickadees; it is a complex burry trilled whistle of chischu-wur and a rich cheelee. They travel in pairs or small groups, and may join multi-species feeding flocks.

The female lays between 5-8 ovate white eggs, marked with fine reddish brown spots. Their breeding biology is not well known, but it is estimated that eggs are incubated for 11-14 days by the female, and the altricial young fledge in 18-21 days.

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Threats
Chief threats include overgrazing, clearing of forests for timber and fuel wood, and development. Other problems stem from recreational pressures and use of the area for military exercises. Exploitation of dead trees for paper fabrication has driven the imperial woodpecker, which once used these trees for nesting and seed storage, to extinction.

The imperial woodpecker, the world's largest woodpecker at a height of almost 60 cm (2 ft), was once widespread in Sierra Madre Oriental pine-oak forests but is now almost certainly extinct because of the loss of old-growth habitat and hunting pressures.
WWF’s work
Working with a wide range of local partners, WWF-Mexico's mission is to achieve major, enduring, and strategic conservation results that simultaneously benefit the livelihoods of Mexico's citizens. One of the major programmes is the Mexico Forest Programme. Nearly 30% of the nation's territory is covered with diverse forest. These forests have high biodiversity value, produce a wide range of economic benefits, and are essential to the well being of many rural and urban Mexican communities.

The Mexico Forest Program started in July 2002 and now has projects in the following areas:
  • Sierra Norte - In the mountainous range of the North of Oaxaca State. Pine-Oak Forest and Cloud Forest.
  • Coastal Mountains - From the Huatulco coast to Nube de Flandes, in the Oaxaca State. Tropical Dry Forest and Pine-Oak Forest.
  • Selva Zoque - Chimalapas. In the border of Oaxaca, Chiapas and Veracruz States. Tropical Wet Forest, Tropical Dry Forest, Pine-Oak Forest, Cloud Forest.
  • Sierra Tarahumara - Upper Conchos watershed, State of Chihuahua. Pine-Oak Forest.
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