The Composition and Spatial Pattern of Nanjenshan Lowland Rain Forests
Date Issued
2008
Date
2008
Author(s)
Chao, Wei-Chun
Abstract
The lowland forests in southern Taiwan and on Lanyu Islet are parts of the remnants of tropical rainforests. Data from four plots and one transect in the Nanjenshan Reserve of southern Taiwan and one plot on the Lanyu Islet were used to understand the structures and compositions of the lowland rainforests at the northern margin of tropical southeastern Asia. All free-standing woody plants in these plots with DBH ≥ 1 cm were included in the analyses. A total of 109,060 individuals belonging to 255 vascular tree species in 141 genera and 59 families were recorded. To provide a quantitatively based classification of these assemblages, both two-way indicator species analysis (TWINSPAN) and detrended correspondence analysis (DCA) were performed. The forests of Nanjenshan and Lanyu were clearly separated in the initial TWINSPAN division and also along the first DCA axis, and this was attributed to the existence of a greater proportion of southern Malesian floristic elements in the Orchid Island forests. Further subdivisions of the dataset into five forest types were closely related to elevation, aspect and exposure. The results suggested that forest composition and structure of the study forests were strongly related to biogeography, regional topographical features and exposure. Spatial patterns of trees in the four lowland rainforests in Nanjenshan were evaluated by Ripley''s K functions. Among the 256 species with more than 15 individuals in these four plots, most species were aggregated in Lanjenchi and Nanjen Lake plots but lower aggregated intensity in Nanjenshan plots I and II. Considering only larger trees, the proportion of aggregation were reduced in each plot, and all species were randomly in Nanjenshan plot II. About 41.2 % of the species shifted from highly aggregated patterns to a low level of aggregation or random distribution with an increase in tree size, and 58.8 % of the species had an inverse pattern. This study revealed that distributions of most species within the Nanjenshan forests were related to habitat heterogeneity and possibly the monsoon wind effect.
Subjects
Spatial pattern
species composition
Nanjenshan
Lanjenchi
Nanjen Lake
Lanyu
Taiwan.
SDGs
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