惠蓀林場杉木人工林區塊伐與其鄰近森林土壤種子庫比較

Comparison of soil seed bank compositions between patch cutting of a Chinese fir plantation and nearby forests in HuiSun Forest Station

本研究於惠蓀實驗林場第三林班地杉木人工林伐採區（伐採面積約1ha）、鄰近未伐杉木人工林和次生林進行土壤種子庫組成比較。植群樣區大小為15m×15m，各取5重複，區分成9個5m×5m的小樣區，並在中心小樣區隨機取1個15cm×15cm的土壤種子庫樣區，依腐質層、0～5、5～10、10～15、15～20cm的土層取樣。地上部植群調查發現49科74屬102種植物，柏拉木、廣葉鋸齒雙蓋蕨、琉球雞屎樹、黃藤、鬼桫欏等為3種林地共同優勢的維管束地被植物；其中，琉球雞屎樹、黃藤在伐採區數量較少，鬼桫欏在次生林分布較少。土壤種子庫試驗共調查400棵種子苗，分屬19科31屬31種；種子儲量前三名分別為揚波、繖花藤和野牡丹，約佔種子儲量60％。杉木伐採區之種子密度為1,422顆／m2，杉木人工林之種子密度為373顆／m2，次生林之種子密度為1,760顆／m2，由種子庫空間分布來看，種子主要集中於土壤0～5cm處，約佔種子儲量41％。降趨對應分析顯示，3林地之地被組成各自形成一群，但3種林地的土壤種子庫組成區分不明顯。Sørensen相似性指數分析發現，土壤種子庫和地被的組成相似性極低，可能顯示由於區塊伐林地疏開後至土壤種子庫試驗僅約半年，區塊伐林地上豐富的殘材與耐陰性植物組成，致使土壤種子庫組成在短期內尚未參與林地擾動後的生育地演替與更新。

Comparison of compositions of the soil seed bank between patch cutting of a Chinese fir plantation and nearby forests was conducted in Hui-Sun Forest Station. The size of vegetation plots was 15×15 m2 ; 5 replicates of each forest type were sampled, and each plot was then divided into 9 subplots of 5×5 m2 . A 15×15 cm2 sampled area of the soil seed bank was randomly obtained from the central subplot, and soil samples were obtained from the humus layer and the soil layers at depths of 0-5, 5-10, 10-15, and 15- 20 cm. Investigation of aboveground vegetation revealed 102 vascular plants, belonging to 74 genera and 49 families. Blastus cochinchinensis, Diplazium dilatatum, Lasianthus fordii, Calamus quiquesetinervius, and Cyathea podophylla were codominant species in 3 communities. Among them, L. fordii and Cal. quiquesetinervius occupied less area in patch cutting of the Chinese fir plantation, and Cya. podophylla occupied less area in the secondary forest. Four hundred seedlings belonging to 31 species, 31 genera, and 19 families, were found in the soil seed bank. The following species occupied approximately 60% of the total seed quantity in the soil seed bank and were thus ranked the top 3 quantities in the soil seed bank: Buddleja asiatica, Morinda umbellata, and Melastoma septemnervium. The secondary forest had the highest seed density (1,760.0 seeds/m²), followed by patch cutting of the Chinese fir plantation (1,422.2 seeds/m²) and the Chinese fir plantation (373.3 seeds/m²). Seeds were mainly found at 0~5 cm depth soil in the soil seed bank, accounting for 41% of the total seed quantity. According to detrended correspondence analysis, understory compositions of the 3 communities could be divided into 3 groups, but such division was not applicable to the soil seed banks. Sørensen similarity index showed that the common compositions between soil seed bank and aboveground vegetation was extremely low. The results indicated that despite the abundance of brushwood and shade-tolerant plants in patch cutting area, their seed quantity was low in the soil seed bank; thus, these plants had not participated in the succession and regeneration of the habitat after disturbance within a short time of patch cutting of the Chinese fir plantation.