碩士 / 靜宜大學 / 生態學研究所 / 97 / In Nanhsi Forest Dynamics Plot (Nanhsi FDP) of 8.37-ha in middle elevation of Taiwan, 50 litterfall traps had been set-up with a systematic design. Litterfall collection and phenological survey had been continued biweekly for one year since November 2007 to November 2008. A total amount of 104437 leaves was collected, with 11971.04 g in dry mass. Annual litterfall was 4.796 t.ha-1. This study was to investigate the dynamics of leaf-fall and phenological patterns of plant population in this plot, in related to plant traits, ecological habits of species and the environmental factors.
First, a taxonomic key to leaves of 35 families and 73 species, including both erect woody plants of 50 species and dependent plants of 23 species was established according to the norms of collected specimen. Principal Component Analysis (PCA) was applied among 39 dominant species in this plot using leaf structure parameters. The principal components were specific leaf area (SLA), texture and ratio of leaf length to width (LW) on axis-1, the forms of leaf margin and venation on axis-2, leaf area on axis-3. Deciduous species located at right-bottom side of the axis-1,2 plane, with the trend of large SLA, chartaceous texture, small LW, serrate margin, and craspedodromous leaf venation. Evergreen canopy trees located at left side on axis-1, with the vines at right side. Still the vines at upper side on axis-3 had smaller leaf area. Under-canopy evergreen trees located at upper side on axis-2 with the trend of entire margin, coriaceous texture , and reticulate venations with less conspicuous lateral veins. The epiphytes and hemiparasites were the two ends of this trends on axis-1,2. The results showed the implications from the leaf structure parameters to the differentiation of plant growth forms, leaf habits, and the vertical layers of forest structure.
Erect woody plants accounted for 85.77% of annual leaf litterfall, with 67.86% form evergreen trees and 17.91% from deciduous trees. Dependent plants contributed the remaining 14.23%. The most leaf litterfall contributed by Castanopsis carlesii, secondly, A. formosana and then, Cyclobalanopsis stenophylloides. The maximum relative contribution of leaf litterfall of per-unit basal area came from Michelia compressa and Elaeocarpus sylvestris. Five leaf phenological patterns were classified according to the forms of leaf litterfall dynamics and its peak: Deciduous-tree-type (DT), uni-peak flush-type leafing and fast turnover (UPF), uni-peak leafing and continuous turnover (UPC), succeeding leafing and continuous turnover (SLC), and multi-peaks due to disturbance (MPD). Deciduous trees of DT type (Acer insulare) had their leaf-fall peak in winter, while expanding new leaves in the next early spring. There were different evergreen canopy trees leafing with UPF type (such as Fagaceae in the plot) both in April and July. Evergreen sub-canopy trees turn over leaves with UPC type (M. compressa and E. sylvestris). The shrubs had both types and SLC type (Eurya loquaiana). MPD type (Litsea acuminata, Machilus japonica, Tetradium glabrifolium, A. formosana) with multi-peaks of leaf-fall which disturbed by typhoons or herbivores. For different growth forms, Erect woody plants turn over leaves continued from April to July as main growth season. The vines produced new leaves more concentrated on April, and earlier than erect woody plants. For spatial relations from the top-slope to valley, or from large crown-gap ratio to smaller one, there existed delayed timing of leaf turnover.
Total 50 species leafing, 46 species flowering and 35 species fruit-mature period were recorded by phonological survey. Mostly species in the plot producing new leaves in April (with the species ratio 37/50), bloomed in May (16/46), and in July and November (both with 8/46) secondly, and matured fruits in December (12/35). There were always some flowering or mature fruiting species in each month during the whole year. Leafing and leaf-fall performance had strong correlations to annual temperature as getting warmer, but not to rainfall factor.
A 3-D structure, which was proposed to explain the phonological patterns and ecological niche differentiation of the 23 dominant erect woody plants in this plot, was modeled with X-axis (also the gap-axis) according to the correlations of leaf-fall dynamics and crown-gaps ratio, and with Y-axis (time-axis) according to leaf phenological patterns, and then with Z-axis (layer-axis) according to the distribution of species in vertical layers of forest. From the outward of gap-axis, the pioneer trees, A. formosana and T. glabrifolium occupied this position which was easily disturbed accompanied with elongated leaf-fall period. Towards inward, then A. insulare, Malus doumeri and Pourthiaea beauverdiana distributed in forest edges or gaps; and then Machilus thunbergii, Rhododendron ellipticum and Eriobotrya deflexa distributed in upper-slop or inner gaps; The evergreen canopy trees, Fagaceae mostly, occupied the deep inward. Species on this trend along the gap-axis might be consistent with the successional stage, and most of them had closely flowering and leafing with DT or UPF type, that usually occurred in early spring; Downwards layer-axis, under-canopy, shade-tolerant species like Osmanthus matsumuranus and Xylosma congesta, or widely-distributed species like M. compressa, E. sylvestris and E. loquaiana had separate or sequent timing of leaf-growth and flowering, and various leaf phonological patterns which were towards longer and more continuous leaf turnover. In this structure, along the layer-axis and gap-axis, all the 23 species got their positions of niche, and showed the differentiation of phonological patterns among different groups like evergreen canopy trees, under-canopy trees, pioneer trees and other deciduous trees. The variations along these two axes were also indicated by the gradient changes of leaf traits in this plot.
| Identifer | oai:union.ndltd.org:TW/097PU005110010 |
| Date | January 2009 |
| Creators | Chi-Yu Weng, 翁其羽 |
| Contributors | Kuoh-Cheng Yang, 楊國禎 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 93 |
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