Madrean Pine-Oak Woodland - Code: Ne1L

Madrean pine-oak woodland is the dominant habitat in the mountains of the far sw. United States, w. Mexico, and Guatemala. It consists of pines and evergreen broadleaf trees. This habitat generally occurs at 5,000–9000 ft. (1,500–2,750m). The climate is temperate to subtropical, with winter lows near 40°F (4°C) and summer highs close to 90°F (32°C). The amount of precipitation is highly dependent on elevation and slope aspect, and Madrean pine-oak woodland receives anywhere from 16 in. (500mm) to 100 in. (2,500mm) of rain per year.
Structurally, Madrean pine-oak woodland varies from open to moderately dense, with canopy coverage in the range of 10–40%. The height of the canopy is highly variable and dependent on dominant species, reaching 50–100 ft. (15–30m). The mid-canopy and tall shrub layers are fairly dense, but the understory is usually open, and this is a pleasant habitat for hiking, especially in shady canyons.
Botanically, this habitat is incredibly diverse, containing over 5,000 species, more than a quarter of the plant species of Mexico. There is high diversity not only in herbaceous plants but among canopy trees as well—over 20 conifer species and nearly 50 oak species are present. No single canopy species is found throughout the entire range, but several of the most widespread and common canopy trees are Apache Pine (Pinus engelmannii), Chihuahuan Pine (Pinus leiophylla), Montezuma Pine (Pinus montezumae), Hartweg’s Pine (Pinus hartwegii), Engelmann Oak (Quercus engelmannii), and Uricua Oak (Quercus laurina). At higher elevations, the canopy is pine-dominated, and occasionally fir trees are present. The mid-story is open to moderately dense and usually comprises smaller oaks and madrones (Arbutus spp.). The understory varies significantly with rainfall and canopy density. Woodlands with a more open canopy have understories dominated by perennial grasses like muhly grasses (Muhlenbergia spp.), lovegrasses (Eragrostris spp.), and Feathergrass (Nassella tenuissima). Small shrubby oaks are also a common feature of the understory, along with manzanitas (Arctostaphylos spp.) and silktassels (Garya spp.). In parts of s. Mexico this habitat can be quite wet and cloudforest like with dense broadleaf and herbaceous understory and pines draped in hanging moss and bromeliads.
 The Oyamel subtype (Sidebox X) is found from 8,000-13,000 ft (2400-4000m) and is dominated by the Oyamel fir (Abies religiosa).