台灣北部羅培山山地雨林的物種組成及森林結構

Abstract

The forest structure and woody species composition were investigated in a montane rainforest of Mt. Lopei in northern Taiwan. All stems ≥ 1 cm dbh were measured and identified for a permanent plot of 1-ha (1,136 to 1,164 m asl.). Approximately 12,934 stems of 70 taxa in 31 families were found. The most abundant families were Fagaceae, Illiciaceae, and Theaceae, representing 51.5% of the individuals. The dominant species, based on basal areas were Cyclobalanopsis longinux, Machilus thunbergii, Cyclobalanopsis sessilifolia, Illicium arborescens, Diospyros morrisiana, and Meliosma seqimulata. Comparison of TWINSPAN groupings with the DCA ordination showed a definitive separation of forest types along a topographic gradient. The categorized forest types were the Cyclobalanopsis longinux-Myrsine seguinii type on the ridgetop and northeastern slope facing strong northeastern monsoon, and the Illicium arborescens-Itea parviflora type on the relatively protected southwestern slope. Evident differences of the composition and structure were observed between these two forest types. Size-class structures of most species showed an inverse J-shaped or an inverse L-shaped distribution, both indicators of a continuous recruitment in this permanent plot.