人工針葉林與天然闊葉林孔隙更新動態研究(3/4)The dynamic of gap regeneration on plantation and natural broadleaf forest (3/4)

1.根據林地幼木發生與適應性監測資料顯示，天然林內所發生的樹種多數為中、後期演替樹種，包括赤皮(Cyclobalanopsis gilva)、火燒柯(Castanopsis hystrix)、紅楠(Machilus thunbergii)、瓊楠(Beilschmiedia erythropholia)、長葉木薑子(Litsea acumunata)、木荷(Schima superba)、烏心石(Michelia compressa var. formosana)等樹種。由於這些剛由掉落林床種子萌芽的當年生幼苗，在林床初期死亡率極高，故其幼苗庫在連續定期的調查數量均呈減少之趨勢。其平均存活率僅8.8%，所有樹種中存活率較高者為殼斗科樹種赤皮及火燒柯，前者達50%，後者更有55%；而瓊楠及長葉木薑子則另屬成活率較高之樟科植物。
2.所有更新存活幼苗的平均苗高僅為14.7公分，其中存活5年的優勢樹種(predominant spp.)其苗高平均亦僅15.3公分，最高者為紅楠，5年生苗高為18.8公分，顯示優勢樹種在林下有覆被的狀況下雖仍能存活，但高生長緩慢。
3.人工針葉林經不同強度疏伐後，中、後期演替樹種苗木發生與存活情形以赤皮最高(100%)，陽性樹種如山胡椒(Litsea cubeba (Lour.) Persoon)、臭辣樹(Tetradium glabrifolium)可在較大林冠孔隙中存活，其中重要樹種經4年後之樹高生長以山胡椒最高。
1.According to the survey datas、evaluated by hatching and adaptation. It revealed the germinated seedlings were mostly belonging to late succession species. Include Cyclobalanopsis gilva, Castanopsis hystrix, Mahilus thunbergii, Beilschmiedia erythropholia, Litsea acuminata, Schima superba, Mahilus compressa var.formosana etc. All of the seedlings were came from newly germinated seeds. Because of the lower survivor rates, the monitoring numbers of forest floor seedlings bank revealed a decline patterns. The means of first years survivor rate of all species in the forest floor are 8.8%. The Fagaceae species C. gilva and C. hystrix have higher survivor rates (50% and 55%).The Lauraceae species B. erythropholia and L. acuminate also have higher survivor rates.
2. The high growth of the survivor seedling at the forest floor are lower. The predominant spp. of the survivor seedling have a 15.3cm mean seedling high. The highest one is Machilus thunbergii.
3. The best hatching and survivors rates the predominating species in coniferous plantation, after thinning practices, are Cyclobalanopsis gilva (100%). The pioneer species e.g. Litsea cubeba (Lour. ) Persoon, Tetradium glabrifolium can survivor in a bigger gap area. Acroding to our monitoring data after 4 years the L. cubeba have the highest tree growth.