Abstract:
The purpose of this study was to develope a plant community classification
within the Siskiyou mountains, a small range within the Klamath
geological province well known for its geologic and floristic diversity.
Forest land managers have expressed the need for identification of
basic Land classes that will aid in the assessment of the applicability
of research results, aid the assessment of the results of management
practices, and aid in the prediction of management techniques needed to
produce specific results. Because of the extreme diversity, such a
classification must be developed locally by intensive sampling and
rigorous analytical techniques.
Thus cluster analysis, discriminant analysis and canonical analysis were
used in combination with a classification table to classify and analyze
250 plotes taken in 100,000 acres the Upper Illinois River drainage. Seventeen communities based on the dominant climax species were
subdivided from six major vegetation groups. The six vegetation groups,
the Abies magnifica shastensis, the Abies concolor, the Chamaecyparis
lawsoniana, the Pseudotsuga menziesii, the Lithocarpus densiflora, and
the Pinus jefferyi were separated on the basis of the dominate tree in both
the understory tree layer and overstory tree layer. A description of
each community, the basic classification unit, is given. The descriptions
include: the results of the classification techniques and their meaning,
the relative environment of each community, species relationships for
the more common species in each community, estimates on their relative
productivity, their successional status, and keys for mapping the communities
and identifying stands.
The geologic and floristic history of the Klamath province is
complex, but it provides a basis for understanding today's flora. The
affects of the Applegate, Galice and Nevadan episodes which were later
modified by the ice advances and the Xerothermic period are presented.
The affects of the major Tertiary plant migrations are also presented.
