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Title: Blue oak plant communities of southern San Luis Obispo and northern Santa Barbara Counties, California

Author: Borchert, Mark I.; Cunha, Nancy D.; Krosse, Patricia C.; Lawrence, Marcee L.;

Date: 1993

Source: USDA Forest Service General Technical Report PSW-139, 49 p.

Publication Series: General Technical Report (GTR)

Description: An ecological classification system has been developed for the Pacific Southwest Region of the Forest Service. As part of that classification effort, blue oak (Quercus douglasii) woodlands and forests of southern San Luis Obispo and northern Santa Barbara Counties in Los Padres National Forest were classified into I3 plant communities using vegetation collected from 208 plots, 0.1 acre each. Three distinct regions of vegetation were identified in the study area: Avenales, Miranda Pine Mountain and Branch Mountain. Communities were classified separately for plots in each region. Each region has a woodland community that occupies flat or gently sloping benches, toeslopes, and valley bottoms. These communities possess a relatively high proportion of large trees (≥ 18 in. d.b.h.) and appear to be heavily grazed. In each region an extensive woodland or forest community covers moderate slopes with low solar insolation. These communities have in common a relatively high density (> 180 per acre) of small-diameter trees (2-6 in. d.b.h.). Xeric communities on moderate slopes with high solar insolation are present in each region. In general, however, blue oak is poorly represented in xeric topographic settings in the study area. Two rare communities occupy steep sites with low solar insolation in the Miranda Pine Mountain and Branch Mountain regions. Each community has high species richness and contains a distinctive set of high constancy species. Finally, upper elevation woodland and forest communities are preqent in Avenales and Branch Mounvdin regions, where both volume and tree density are high. Keys to the plant communities are included in an appendix. These communities will serve as a framework for gathering productivity and management information for further refinement.

Keywords: Quercus, Quercus douglusii, vegetation classification, California oaks, blue oak

Publication Notes:

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Borchert, Mark I.; Cunha, Nancy D.; Krosse, Patricia C.; Lawrence, Marcee L. 1993. Blue oak plant communities of southern San Luis Obispo and northern Santa Barbara Counties, California. Gen. Tech. Rep. PSW-GTR-139. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; 49 p.


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