南仁山低地雨林凋落物之研究

Abstract

本研究的目的，在於探討南仁山低地雨林凋落物變化的情形，並與1992-1993年在欖仁溪樣區所做的凋落物研究作一比較。研究地點依南仁山西北側稜線所設置的長形樣帶（海拔250-480公尺），採系統取樣設立了45個收集網，按月收集凋落物。 就1995年9月到1997年8月所收得的兩年資料，可得總凋落量為分別為11.77和9.43t/ha，其中落葉量為7.96和6.43t/ha、枝條為2.42和1.82t/ha、果實為0.56和0.57t/ha，花為0.15和0.13t/ha。總凋落量與其他熱帶森林相似，凋落物季節變化呈現雙高峰，出現在3-5月生長季和7-9月颱風季節，比欖仁溪樣區的情形多了颱風的影響因數，而東北季風的影響不顯著。 依樹種凋落型態，可區分成3月生長季凋落型、7-9月颱風型、10-2月東北季風凋落類型，除颱風屬於非正常穩定的凋落影響外，以3月生長季凋落類型（如殼鬥科）最明顯。 在可鑑別出的140種植物中，喬木有88種，灌木有11種，蕨類有8種，藤本則有33種，落葉主要組成樹種依次為白榕（佔總落葉量的7.89％）、茄苳（6.39％）、嶺南椆（4.15％），而藤本總共佔了總落葉量的17.14％，呈現相當明顯的熱帶特性，前三名依次為莎勒竹（4.04％）、疏花魚藤（3.71％）、亨利氏伊立基藤（2.99％）。 經DCA分析的結果，可將落葉網設置地點，依海拔分佈區分成三群，與廖（1995）所得的樹冠層資料分成三個植物社會相符合。第一群（溪穀區）的凋落量最大，以白榕、茄苳、鐵冬青為落葉優勢，第二群（樣帶中段）為鳥心石、江某和細脈赤楠，第三群（山頂區）以嶺南椆、高士佛赤楠、錐果櫟、金平冬青為主。 將此三群植物社會的凋落變化作一比較，可發現三群在第一年總凋落量上，能將溪穀區和山頂區在統計上明顯區分出來，而樣帶中段則與溪穀區較相近，而每月的凋落變化情形，三群則極為相似。

The purpose of this study is to understand the pattern of litterfall along altitudinal gradient in the Nanjenshan lowland rain forest, and to compare the litterfall from 1992 to 1993 in the Lanjenshi plot. 45 traps were placed systematically along the northwestern ridge of Nanjenshan. All samples were collected monthly and separated into leaves, branches, flowers, fruits, and miscellaneous fractions. Annual litterfall from October 1995 to September 1997 was 11.77 and 9.43 t/ha, respectively, of which 7.96 and 6.43 were leaves, 2.42 and 1.82 woody parts, 0.56 and 0.57 fruits, 0.15 and 0.13 flowers. The annual litterfall was similar with other tropical forests and higher than that of the Lanjenshi plot. The seasonal pattern of litterfall showed two pronounced peaks: during the growth season (from March to May) and the typhoon periods (from July to September). The effect of northeastern monsoon (from October to March) on litterfall was not significant. Leaf-fall can be divided into three patterns: the growth season, the typhoon periods and the northeastern monsoon periods. Except the typhoon periods belonging to the unsteady litterfall pattern, the growth season leaf-fall was the most important pattern. A total of 140 species, belonging to 64 families and 102 genera, were collected. Among them 88 were trees, 11 shrubs, 8 ferns and 33 lianas. The most dominant species was Ficus benjamina (7.89% of leaf litterfall), followed by Bischofia javanica (6.39%) and Cyclobalanopsis championii (4.15%). Lianas, responsible for about 17.14% of leaf litterfall, showed tropical characteristics. The dominant species of lianas were Schizostachyum diffusum (4.04% of leaf litterfall), Schizostachyum diffusum (3.71%), and Erycibe henryi (2.99%). Result of DCA indicated that the traps on transect can be divided into three groups along the altitudinal gradient. This coincides with the three vegetation zones from crown data. The litterfall of valley zone was higher than other zones, and was dominated by Ficus benjamina, Bischofia javanica, Ilex rotunda. The slope zone was dominated by Michelia compressa, Schefflera octophylla and Syzygium euphlebium. On the ridge zone, Cyclobalanopsis championii, Syzygium kusukusense, and Cyclobalanopsis longinux were the dominant species of leaf litterfall.