南仁山區熱帶季節性森林的組成、結構及分佈類型

Abstract

設立於南仁山區背風坡面近溪穀處的2.1公頃永久樣區，自1992年夏季開始進行研究，調查森林中木本植物DBH＞1公分者，記錄其胸高直徑，並加以編號。直至1994年春季方完成基本資料的初步收集。 樣區內共記錄木本植物107種，分屬於43科77屬。其中以九節木、茄苳、紅果椌木、白榕等，?森林中的優勢樹種。而以茜草科、大戟科、楝科、桑科等泛熱帶分佈的科群?森林中優勢科。且具有若干熱帶雨林的特性，如板根、支柱根、大型木質藤本等，然而在氣候條件及森林形相上，本森林與熱帶雨林之間，仍有相當的差異。與謝等人（1992）在南仁山區近稜脊處所調查的3公頃永久樣區相較，在植物組成、密度及森林形相上，都有明顯的不同。 在樹種的空間分佈上，大多樹種皆呈現隨機分佈，少數則受地形環境或幹擾等因素之影響，呈現聚集分佈的現象。此外，由族群結構的分析，顯示此森林不斷地遭受規模不等之幹擾，如人?砍伐，因此造成森林演替階段處於不穩定的狀態，未達氣候之極盛相。

A 2.1-ha permanent plot was established in summer of 1992 in Nanjenshan leeward region. The permanent plot was established for the purpose of studying floristic composition, forest structure and spatial distribution patterns. Field data collection was proceeded until spring of 1994. 107 woody species with DBH ? 1 cm were recorded in the permanent plot, including 77 genera and 43 families. From the Important Value Index calculated, Psychotria rubra, Bischofia javanica, Dysoxylum kuskusense and Ficus benjamina were dominant species. I found the above species were common tropical elements, belonging to the families of Rubiaceae, Euphorbiaceae, Meliaceae and Moraceae respectively, which were common to most tropical forests. The forest bore some similarities to tropical forests both in physiognomy and structure. It was rich in thick-lianas and in woody as well as herbaceous epiphytes. In addition, some species showed buttresses or stilt roots. The Physionomy and species composition of this forest were markedly different from the other 3-ha permanent plot established in 1990 in Nanjenshan ridge region. The analysis of the spatial patterns for each species indicated that most of them were randomly distributed, few showed clumping distributions which were consistent with the topographic zonations or disturbed area. Size-class distributions of individual species exhibited variable patterns that seemed to be related to broad ecological characteristics of the species. The results also suggested that the forest has been frequently disturbed, and a climax status has not been attained.