Natural Seeding and Seedling Occurrence in the Chamaecyparis Forest at Chilan Mt. Area

棲蘭山區檜木林天然下種及種苗發生之研究

張乃航(Nai-Hang Chang) ； 許原瑞(Yen-Ray Hsui) ； 洪富文(Fu-Wen Horng) ； 游漢明(Han-Ming Yu) ； 馬復京(Fu-Ching Ma)

《台灣林業科學》 16卷4期 (2001/12) Pp. 321-326

https://doi.org/10.7075/TJFS.200112.0321

摘要

紅檜及台灣扁柏為台灣山區霧林帶的重要構成分子，木材質佳，價格昂貴，多年來為林業收穫的主要樹種，但近年來在棲蘭山區收穫倒木及枯立木是否會對檜木森林更新造成影響，一直被許多關心檜木林經營問題的團體關注著。
我們嘗試不同年度枯立倒木整理的林地內找尋檜木林天然下種及幼苗發生、存活的形式，也希望多少能夠知道該地區枯立倒木整理及收穫是否會影響檜木林的天然更新能力。在170、160、130線三個地區選定三個樣區來代表整理後14、8及1年三個區隔，檜木種子天然下種量在三個地區然異不顯著，但種子發芽率則差異甚大。除草或除草加土壤干擾兩種處理對種子發芽率和存活的比例上並沒有差別，根據所得到的結果來看，如果枯立倒木的整理能夠配合豐年期來作業，並在種子成熟期之前結束，空出來的林床即可提供種子著床發芽且亦能減少幼苗遭受雜草競爭的壓力而提高存活率。調查結果亦顯示，在枯倒木上的幼苗存活率最高，這樣的結果是因為較高位置的枯木可以降低幼苗與雜草的競爭，因此，要留存多少較大徑級的枯木（較小徑級枯木並不能提供類似的環境）在林床上才足夠，是後續價得研究的課題。

關鍵字

紅檜 ； 台灣扁柏 ； 枯立木 ； 倒木

並列摘要

Chamaecyparis formosensis and Chamaecyparis obtusa var. formosana are 2 important tree species in the cloud forest zone in Taiwan. Because their wood quality and price are high, they have long been the major harvested timber species. Whether current harvesting of snags and downed logs in the natural Chamaecyparis forest at Chilan, north Taiwan, causes negative or positive impacts on Chamaecyparis regeneration is a concern of all parties involved in Chamaecyparis forest management issues. We tried to estimate natural seeding and seedling survivor patterns on forest floors with different time spans after harvesting of snags and downed logs at Chilan. Three sites along forest roads 130, 160, and 170 were selected to represent sites 1, 8, and 14 years after snag and downed log harvesting, respectively. Results indicate that the numbers of seeds collected at the 3 sites did not significantly differ from each other, but their germination rates differed. As to weeding and weeding with soil disturbance, these 2 practices did not significantly enhance seedling occurrence or survival rates. The Chamaecyparis forest has a very obvious recurring mast year every 3-5 years, and it is recommended that harvesting operations be conducted in mast years. Under such circumstances, the seedbed would have been recently prepared, and weed and shrub competition eliminated by the harvesting operation. On the other hand, the higher survival rate of seedlings on downed logs indicates that leaving some large downed logs on the ground is beneficial to seedling establishment. But, the number of large downed logs that should be left needs to be further studied.

並列關鍵字

Chamaecyparis formosensis ； Chamaecyparis obtusa var. formosana ； snags ； downed logs