| Summary: | 碩士 === 國立臺灣大學 === 森林學系 === 84 === The forest vegetations of the Machilus-Castanopsis zone of
Northwestern Taiwan were analyzed. The annual temperature of
study area ranges from 15.5-22.7℃. The annual precipitation is
more than 2000mm. Most of the precipitation occurs during the
summer. Dry season varies from one to six months during the
autumn and winter. Such climate condition determines the vege-
tation characteristics of this area. This study based on 33
sample plots, with 255 recorded woody species. In each plot, 6
environmental factors were measured. According to the detrended
correspondence analysis (DCA), cluster analysis and tabular
comparison, I divided the forest into four vegetation types and
five subtypes. The lower Quercus Zone in- cludes: I.
Cyclobalanopsis longinux-Trochodendron aralioides forest type
and IA. Rhododendron formosana forest type. The Machilus-
Castanopsis Zone includes those on mid-altitude and upper
mountain valley: II. Listea acuminata-Michelia compressa forest
type, IIA. Rhus succedanea-Pasania brevicaudata forest type,
IIB. Listea acuminata-Machilus japonica forest type; those on
the lower altitude area: III. Cyclobalanopsis glauca-
Engelhardtia roxburghiana forest type; those on mid-altitude
and the lower valley: IV. Ficus irisana forest type, IVA.
Machilus japonica var. kusanoi-Bischofia javanica forest type,
IVB. Ficus irisana-Zelkova serrata forest type. Through
population structure analysis, it is concluded that most of the
dominant species of these forests show good regeneration. Thus
all these forest types are nearly stable communities. The study
area is faced with great development pressure, but still
receives no conservation measure. Eight rare or vulnerable
plant species are listed as a guideline for conservation
management.
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