Poster Sessions Concurrent Sessions Conference Proceedings Oak Symposium Home This paper was not included in the Symposium Proceedings.	Pre-Symposium Abstract of Paper The Demography and Distribution of the Engelmann Oak Thomas Scott Integrated Hardwood Management Program, University of California, Berkeley, and Center for Conservation Biology, University of California, Riverside. Scott Mensing Department of Geography, University of Nevada, Reno Richard Minnich Department of Earth Sciences, University of California, Riverside The range of the Engelmann oaks (Quercus engelmannii) overlaps the most rapidly urbanizing counties of California, with the highest rates of habitat conversion. Nevertheless, stands of this species that are not challenged by land conversion appear to be expanding into abandoned dry-farms and grazing lands. Aerial photographs from the 1920s suggest that these areas were heavily altered by management practices at the turn of the century, and that this expansion either represents a re-colonization of former habitats or opportunistic use of areas where the original species were extirpated. Most trees (>10 cm dbh) in these stands are relatively young (averaging 62 + 27 [SD] yrs) although a small portion (4.6%) of the trees we cored (n=1085) were >100 years old. This current expansion of Engelmann oaks stands contradicts the highly limited range of the species (the smallest of any oak tree in North American). L. Benson suggested that Q. engelmannii trees were swamped by scrub oak species in hybrid zones; this appears to be the case along the western margin of the Q. engelmannii range. Q. engelmannii also has been less successful than the live oaks (Q. argifolia, Q. wizlizenii) in summer drought areas (coastal southern California and Baja California), and in winter frost areas (upper Palomar and San Jacinto Mountains). The stems of Q. engelmannii are more susceptible to fire damage than Q. agrifolia, Q. engelmannii may be less palatable to herbivores. Judged by its natural history, Q. engelmannii appears to be a subtropical Mexican oak surviving in a small area of equitable Mediterranean climate. Like Q. peninsularis, Q. engelmannii has been separated from its closest congeners by the intrusion of inhospitable desert climates and the tectonic features of the Baja and Alta California.
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