Ecological site group description

Provisional. A provisional ecological site description has undergone quality control and quality assurance review. It contains a working state and transition model and enough information to identify the ecological site.

Physiography

This ESG is generally found on slopes that are steep, rocky, and dry. Pinyon-juniper may exist on deeper valley soils, but tree size and density increase as elevation increases and soil depth decreases. Characteristic landforms include gently rolling hills to steep mountain slopes, rocky canyons, and narrow ridges.

Climate

Climatic conditions include low precipitation and relative humidity, hot summers with high evapotranspiration rates, and clear weather with intense sunlight. Potential evapotranspiration in from one to four times as great as precipitation.

Soil features

This ESG currently groups the thermic and mesic soils associated with the pinyon and juniper woodlands. Soils are mostly residual or recently weathered, typically rocky, coarse, porous, and well drained.

Representative soils for this ESG include Osito family, Springdale family, Lithic Xerorthents, and Olete family.

Vegetation dynamics

This ESG is dominated by pinyon-juniper (PJN) and is typically is an open woodland of low, round crowned, bushy trees that are needle-leaved, evergreen, and depending on site suitability, range from less than 10 m (30 ft) to 15 m (50 ft) in height. Crowns of individual trees rarely touch and canopy cover generally is less than 50 percent. These open groves of overstory trees often have a dense to open layer of shrubs reaching heights of 1.5 m (5 ft). Low herbaceous plants may also be present in this habitat.

Stand structure varies depending on site quality and elevation. On favorable sites with little disturbance, pinyon-juniper forms dense cover; whereas on drier sites, spacing between trees increases and tree size decreases. At low elevations, pinyon-juniper stands are rather open, becoming denser at higher elevations. At maximal elevations, this habitat grades rapidly into adjacent habitats.

Overstory species composition at lower and mid-level elevations ranges from pure stands of singleleaf pinyon to stands of pinyon mixed with juniper (California),or oaks (California scrub or canyon live). At higher elevations, Jeffrey pine may also be found. Shrub-size plants in the subcanopy include small individuals of the overstory species, especially California juniper, as well as big sagebrush, blackbrush, common snakeweed, narrowleaf golden bush , Parry nolina, curlleaf mountain mahogany, antelope bitterbrush, Parry rabbitbrush, chamise, and redshank, with an herbaceous layer of grasses and forbs associated with this habitat include western wheatgrass, blue grama, and Indian ricegrass.

Information from:

California Wildlife Habitat Relationships System
California Department of Fish and Game
California Interagency Wildlife Task Group
By William F. Laudenslayer Jr. and Jerry R. Boggs

Hilberg, L.E., W.A. Reynier, and J.M. Kershner. 2017. Southern California Pinyon-Juniper Woodland Habitats: Climate Change Vulnerability Assessment Synthesis. Version 1.0. EcoAdapt, Bainbridge Island, WA. This document is available online at the EcoAdapt website (http://ecoadapt.org/programs/adaptation-consultations/socal).

Major Land Resource Area

MLRA 019X
Southern California Coastal Plains and Mountains

Subclasses

• F019XG913CA–Loamy Hills
• F019XI200CA–Pinus muricata/Quercus pacifica 13-24" p.z.
• F019XI201CA–Pinus torreyana var. insularis/Nassella pulchra 21-31" p.z.
• R019XD001CA–CLAYEY
• R019XI100CA–Loamy slopes 13-31" p.z.
• R019XI102CA–Shallow uplands 13-24" p.z.
• R019XI105CA–Deep slopes 13-24" p.z.
• R019XI106CA–Shallow slopes 13-31" p.z.
• R019XI109CA–Shaly slopes 13-24" p.z.
• R019XI110CA–Concave slopes 13-24" p.z.
• R019XI112CA–Moderately deep volcanic slopes 13-31" p.z.
• R019XI113CA–Loamy volcanic slopes 13-24" p.z.
• R019XI116CA–Clayey slopes 13-31" p.z.

Correlated Map Unit Components

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Stage

Provisional

Contributors

Curtis Talbot