San Diego Management & Monitoring Program


Engelmann Oak
Quercus engelmannii


Kingdom Phylum Subphylum Class Order Suborder Family

Current distribution rangewide

Eastern Los Angeles County to northwestern Baja California, Mexico [1]. Smallest distribution of any California oak species.


Known Populations in San Diego County

Forty-six occurrences on Conserved Lands in MUs 3 (Crest-Worley Preserve, Hollenbeck Canyon Wildlife Area, Lawrence and Barbara Daley Preserve, Otay Mountain Ecological Reserve, Otay Mountain Wilderness Area, Otay Ranch Preserve, Sycamore Canyon Preserve, Sycuan Peak Ecological Reserve, Wright's Field), 4 (BLM, Boulder Oaks Preserve, Cleveland National Forest, El Capitan Open Space Preserve, El Capitan Reservoir Open Space, Louis A. Stelzer County Park, Mt. Woodson, Mt. Gower Preserve, SDG&E Sunrise Power Link Parcels, Simon Preserve), 5 (Boden Canyon Ecological Reserve, Cleveland National Forest, Hellhole Canyon Preserve, Ramona Grasslands Preserve, Sutherland Reservoir Open Space), 6 (Daley Ranch Open Space Preserve, Hodges Reservoir Open Space, Lake Wolford, Lake Wolford Watershed), 8 (BLM, Cleveland National Forest, Margarita Peak, Mount Olympus Preserve), 9 (Cleveland National Forest, Santa Ysabel East Open Space), 10 (Cleveland National Forest, Eagle Peak Preserve, Mesa Grande Easement, Santa Ysabel West Open Space Preserve), and 11 (Barrett Reservoir Open Space, Cleveland National Forest, Potrero Park, Sunrise Power Link Parcels).


List status

None [1].


Habitat affinities

Chaparral, cismontane woodland, riparian woodland, valley and foothill grassland [2]. Found on mesas with elevation range of 700 -1250 meters [3].


Taxonomy and genetics

Fagaceae family [2]. Known to hybridize with scrub oak species (Q. cornelius-mulleri, Q. berberidifolia, and Q. durata) [3].


Life history demography

Semi-deciduous tree [4]. Produces acorns within 1 year [5]. May be better adapted for establishment in more exposed habitats than Q. agrifolia because it is less sensitive to moisture loss, will germinate with little or no additional water uptake, is self-rooting, and has delayed shoot development.


Seasonal phenology

Bloom period March-June [2]. Acorn drop occurs September-November [5].


Pollination seed dispersal

Wind-pollinated [3]. No persistent seed bank since acorns do not survive more than 1 year [5].


Threats

Development [2] and lack of natural recruitment due to grazing [4]. Competition for underground resources between oak seedlings and exotic grasses.


Special considerations:

As a white oak, it is at low risk from Goldspotted Oak Borer (Agrilus auroguttatus) [1]. Poor host plant for grasshoppers [4].


Engelmann Oak sources