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The Distribution of Engelmann Oak (Quercus engelmannii) in CaliforniaAuthor(s): Thomas A. Scott
Source: In: Standiford, Richard B., tech. coord. 1991. Proceedings of the symposium on oak woodlands and hardwood rangeland management; October 31 - November 2, 1990; Davis, California. Gen. Tech. Rep. PSW-GTR-126. Berkeley, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; p. 351-359
Publication Series: General Technical Report (GTR)
Station: Pacific Southwest Research Station
PDF: View PDF (1.7 MB)
DescriptionEngelmann oaks (Quercus engelmannii) only occur in the foothills of San Diego (93 pct of extant stands), Riverside (6 pct), Orange (0.5 pct), and Los Angeles (<0.1 pct) counties, covering the smallest range of any oak species in California. The overall distribution of the species covers approximately 31,500 hectares of woodlands, although they are subdominant (contributing <50 pct of canopy area) to coast live oak (Quercus agrifolia) over about 52 pct of that area. Individual stands across the species range were mapped at 1:24,000 scale into a geographic information system (using 1:20,000 scale aerial photographs). Stands were separated into 6 classes of Engelmann oak canopy dominance: (one) 0 to 5 pct of canopy area; (two) >5 to ≤25 pct; (three) >25 to ≤50 pct; (four) >50 to ≤75 pct; (five) >75 to ≤95 pct; and (six) >95 to ≤100 pct. All areas were field checked for accuracy in boundary and canopy classification. There are approximately 7,300 ha of woodlands in categories five and six; 14,000 ha in categories three and four; and 9,200 ha in categories one and two. Combining these data with USGS Digital Elevation Models suggests that Engelmann oaks are most concentrated on 0° to 10° slopes with southwestern aspects between the elevations of 700 m to 1250 m above sea level. They tend to occur at higher elevations and slightly steeper slopes (5° to 10°) than coast live oaks, but there are no differences in the distribution of the two species relative to slope-aspect. The largest landholder of Engelmann oak stands is the Cleveland National Forest (24 pct of all stands), followed by Spanish Land Grants (29 pct; unbroken large land holdings), Native Americans (7 pct; on Indian Reservations), and the US Marine Corps (6 pct; Camp Pendleton). A large number of small private parcels control the remaining 31 pct of Engelmann oak stands.
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CitationScott, Thomas A. 1991. The Distribution of Engelmann Oak (Quercus engelmannii) in California. In: Standiford, Richard B., tech. coord. 1991. Proceedings of the symposium on oak woodlands and hardwood rangeland management; October 31 - November 2, 1990; Davis, California. Gen. Tech. Rep. PSW-GTR-126. Berkeley, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; p. 351-359
- Insect-oak interactions with coast live oak (Quercus agrifolia) and Engelmann oak (Q. engelmannii) at the acorn and seedling stage
- Germination Characteristics of Engelmann Oak and Coast Live Oak from the Santa Rosa Plateau, Riverside County, California
- Coast Live Oak Thinning Study in the Central Coast of California-Fifth-Year Results
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