Oak/pinyon/juniper woodland on fans and pediments derived from old alluvium and sedimentary rocks

The view SE towards the Little Rincons from the Happy Valley Road, overlooking a manzanita and white oak thicket typical of this ecological unit. The foreground clearing holds tanglehead grass and, just beyond, dead manzanita.

This small ecological unit is restricted to the east side of the Rincons, where a Pleistocene fan of alluvium sits between the Happy Valley Road and the sudden rise up to Happy Valley Saddle and Rincon Peak. Here, between 4100 and 4400 feet, the dominant landform (62%) is gently sloping hills. The vegetation is thick manzanita (25-39% cover) with associated emory oak (10-14% cover). The manzanita is typically 6 to 7 feet tall, while the oak is 12 to 14 feet tall. Other commons species include white oak, fairy duster, bear grass, shindagger, pinyon and alligator juniper. Grasses are abundant, particularly tanglehead and sprangletop, and together they add another 25% cover. Mesquite is uncommon.

Desired Conditions

Desired conditions are adapted from Madrean encinal woodland, mid-scale desired condition statements in March 2010 Coronado National Forest planning documents.

The size and number of patches of dense trees varies depending mostly on aspect, and to a lesser degree disturbance, soil type, and site productivity. Patch sizes vary, but are mostly tens of acres. Grasses, forbs, shrubs, tree litter, and small trees provide fuel for the natural fire regime with a greater proportion of the ground cover as grasses and forbs as opposed to litter. Vegetation structure in the wildland urban interface (WUI) has a broad mix of different landscapes, such as open areas and scattered groups or clumps of woodland tree species.

Historic Mean Fire Return Interval (Schussman et al. 2006 literature review)

2.5-10 years for Madrean encinal woodland

Primary treatment options (estimated representative project size range):

• Wildland fire: Prescribed fire and/or wildfire to maintain openings, reduce ground fuels, and site prep (1,000 to 30,000 acres per project)

Supplemental treatment options (estimated representative project size range):

• Thinning to maintain openings and around developments for safety-related fuel reduction (up to 500 acres per project)

Other considerations 

May be wilderness considerations with treatments

Other Vegetation Classifications: