Identity
Unique IDELEMENT_GLOBAL.2.144542
Element CodePDFAG05270
Record TypeSPECIES
ClassificationSpecies
Classification StatusStandard
Name CategoryVascular Plant
IUCNLeast concern
Endemicoccurs (regularly, as a native taxon) in multiple nations
KingdomPlantae
PhylumAnthophyta
ClassDicotyledoneae
OrderFagales
FamilyFagaceae
GenusQuercus
Other Common NamesSonoran scrub oak (EN) Sonoran Scrub Oak (EN) Turbinella Live Oak (EN)
Concept ReferenceKartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Taxonomic CommentsFormerly, California populations of what here is referred to as Quercus john-tuckeri have been included in the concept of Quercus turbinella. Q. john-tuckeri has subsessile fruit and noncordate leaf bases as opposed to the consistently pedunculate fruit and strongly cordate leaf bases of Q. turbinella. The two species seem to be no more closely related to each other than each might be to other southwestern oaks, and Q. john-tuckeri shares at least as many characteristics with Quercus berberidifolia as with Q. turbinella. Thus, treatment of these two taxa as varieties of the same species is inappropriate (Tucker, 1961; Flora of North America, 1993). Varieties of Quercus turbinella are now recognized at the species level (Kartesz' 1999 data). Quercus turbinella var. ajoensis is treated as Q. ajoensis, and Q. turbinella var. californica as Q. john-tuckeri.
Conservation Status
Review Date2010-11-22
Change Date1988-08-31
Edition Date2010-11-23
Edition AuthorsCordeiro, J.
Range Extent20,000-200,000 square km (about 8000-80,000 square miles)
Rank ReasonsIt occurs in the mountains of southwestern Colorado through southern Utah and Nevada to southern California and northern Mexico. It is considered relatively secure throughout its range although fossil evidence indicated in previously occurred much further north but climate change eliminated most northern populations so the species may be susceptible to climate changes today, as well. Also, frequency, intensity, and extent of late spring freezes, and intensity and extent of the "Arizona monsoon" appear to be the major factors controlling successful sexual reproduction.
Range Extent CommentsIt occurs in the mountains of southwestern Colorado through southern Utah and Nevada to southern California and northern Mexico (Little, 1979; Tucker, 1961; Tirmenstein, 1999). It extends eastward to the northwestern portion of the Trans-Pecos region of western Texas (Little, 1979). Shrub live oak is most abundant in the chaparral of central Arizona (Cottam et al., 1959; Pase, 1969; Pond, 1961). Shrub live oak-Gambel oak hybrids have been reported hundreds of miles north of the present-day range of shrub live oak in parts of northern Utah and central Colorado (Cottam et al., 1959; Tucker et al., 1961). Macrofossil evidence suggests that shrub live oak migrated northward in the warmer altithermal (or hypsithermal) period during which the Arizona monsoon shifted (Cottam et al., 1959; Neilson and Wullstein, 1983). Later climatic shifts to cooler temperatures presumably eliminated shrub live oak from this northern area, but the more cold-hardy hybrids survived in some protected areas (Cottam et al., 1959).
Threat Impact CommentsShrub live oak is drought tolerant and typically occupies drier and warmer sites than Gambel oak (Neilson and Wullstein, 1983; 1985). In the northern part of its range, shrub live oak often grows on warm, dry, southern exposures (Ffolliot and Thorud, 1974). Arizona chaparral is characterized by a biseasonal precipitation pattern with summer and winter precipitation and spring and fall droughts (Davis, 1870). Annual precipitation averages 16 to 25 inches (410-640 mm) (Ffolliot and Thorud, 1974). Shrub live oak is well adapted to survive fire (Tirmenstein, 1999). This oak typically sprouts vigorously from the root crown and rhizomes in response to fire or other types of disturbance (Davis and Pase, 1977; Pase, 1969; Saunier and Wagle, 1967; Wright et al., 1979). Postfire establishment by seed also occurs.