南仁山區亞熱帶雨林小苗更新之研究

Abstract

本研究在?春半島南仁山亞熱帶雨林三公頃永久樣區內，設立30個5×1m2的樣區，對所有木本植物的小苗標記、鑑定、測量高度，並每隔一個月再複查一次，研究森林下層小苗族群之動態變化。 在14次的調查期間，共記錄小苗73種3500株；小苗的總存活率為69.94％，而首次調查的1673株小苗存活率則為80.75％。密度受出生與死亡的影響呈季節性的變化。小苗萌發有兩個主要的時期，一為12月至3月冬季與春季之間，另一為夏季6月至7月；小苗的死亡則集中於4月至8月之間，大部份的小苗是於出生後三個月內死亡。 各生育地間小苗的密度以強風區最高，背風區最低；歧異度則以緩風區較高，背風區則呈季節性變化；存活率以緩風區最高，背風區最低。由典型對應分析（CCA）的結果可說明小苗的分佈與其所處生育地的坡向、土壤含水量及植被類型有關。 以目前小苗的研究，其組成與結構可反映南仁山森林的植物社會，而存在各生育地間的差異及不同種類更新的策略則是影響小苗存活及生長的主因。

Seedling dynamics were studied in thirty small plots of 5 × 1 m2 in size placed in a 3-ha permanent plot established in Nanjenshan subtropical rain forest on Hengchun peninsula, Taiwan. Seedlings of woody species in permanent plots were tagged, identified, measured and recensused every month. A total of 3500 seedlings in 73 species were analyzed by 14 censuses and survivorship of all tagged seedlings was 69.94%. Survivorship of the first census was 80.75%, comprising 1673 individuals of mixed ages and species. The density varied seasonally by birth and death of seedlings. There were two main birth seasons, one is between winter to spring, i.e. December to March, and the other is during summer between June to July. Most seedlings were dead within first three months after birth, and the peaks were concentrated from April to August. Seedling density was higher in the windward habitat than in the leedward habitat. The intermediate habitat had the highest diversity. The leedward habitat showed a seasonal variation. The highest survivorship was found in the intermediate habitat, while the leedward habitat was the lowest. Canonical Correspondence Analysis (CCA) suggested that seedlings composition and distribution were influenced by aspect, soil moisture and vegetation type. Prior to my study, seedling assemblage of composition and structure appeared to reflect the adult community at Nanjenshan. Different habitats and regeneration strategy were the main factors influencing seedlings establishment.