Wednesday, January 18, 2012

Ecological Systems: Southern Rocky Mountain Pinyon-Juniper

The Southern Rocky Mountain Pinyon-Juniper ecological system is similar to the Colorado Plateau Pinyon-Juniper system, but with a more restricted distribution in south central Colorado. In Colorado, the southern Rocky Mountain pinyon-juniper woodlands are found in the south central part of the state, around the San Luis Valley, southern mountain front east to Mesa de Maya, and north to the Arkansas River Valley and Palmer divide. Elevations range from about 5,000 to 9,000 feet. Pinyon-juniper also occurs in a limited distribution on the eastern plains near the Purgatoire River. These are open woodlands of warm, dry sites on mountain slopes, mesas, plateaus, and ridges. Pinyon pine and/or one-seed juniper dominate the tree layer, and Rocky Mountain juniper may be present at higher elevations. In the canyons and tablelands to the east, pinyon is absent, and this system is replaced by the Southern Rocky Mountain Juniper Woodland and Savanna system. Understory layers are variable and may be dominated by shrubs, grasses, sparse vegetation, or bare ground.

Southern Rocky Mountain pinyon-juniper covers some 1.25 million acres in Colorado. Ownership is divided about equally between private and public ownership, with the Bureau of Land Management responsible for the majority of federal holdings. Pinyon-juniper ecological systems have declined in both extent and quality compared to historic norms, although there are a number of very large patches remaining. Threats include urban development, recreation (especially motorized recreation), invasive species (most notably an increase in cheatgrass in the understory, which has led to increasing fire ignitions), and energy development.

Overall biodiversity, threat, and protection status scores for
Colorado Plateau Pinyon-Juniper in Colorado.
 A "windrose" graph depicting Colorado Plateau Pinyon-Juniper status for individual scoring factors.

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