| Summary: | 碩士 === 國立中興大學 === 生命科學系所 === 94 === The vegetation of Piluchi watershed, a part of Techi Reservoir basin, were investigated, classified and mapped. 57 plots were sampled in the study area. The diameter at breast height (DBH) of overstory and the coverage of understory species were investigated. Totally 545 species of vascular plants, belonging to 294 genera and 113 families were found. Of them 187 species were endemic in Taiwan, and 48 species including 19 endemic species were recognized as rare species, that have to be strictly protected.
According to floristic compositions of the plots, 9 vegetation types were classified by matrix cluster analysis (MCA) and detrended correspondence analysis (DCA). The distributions of vegetation types were related to the altitude. From high to low elevation, vegetation types are: (A) Yushania niitakayamensis type, (B) Juniperus squamata var. morrisonicola type, (C) Rhododendron rubropilosum var. taiwanalpinum type, (D) Tsuga chinensis var. formosana type, (E) Pinus taiwanensis type, (F) Cyclobalanopsis stenophylloides type, (G) Pseudotsuga wilsoniana type, (H) Alnus formosana type, and (I) Cinnamomum insulari-montanum type.
The main disturbances on the vegetation in Piluchi watershed are wildfires and debris flows. Pinus taiwanensis type was commonly found on the sites disturbed by wildfires, and would gradually succeed into Tsuga chinensis var. formosana type, Cyclobalanopsis stenophylloides type, Pseudotsuga wilsoniana type, or Cinnamomum insulari-montanum type, if there is no fire for a long time. If no debris flow occurs, the vegetation by the riverside, such as Pinus taiwanensis type, Cyclobalanopsis stenophylloides type and Alnus formosana type, would probably succeed into Cinnamomum insulari-montanum type.
Based on the vegetation types for map units, this study also provided a vegetation map of Piluchi watershed for related research and management. For the conservations of biodiversity, soil and water, all man-caused illegal disturbances should be strictly prohibited in the watershed.
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