台灣中部暖溫帶老齡常綠闊葉林的植群動態

Vegetation Dynamics in a Warm Temperate Old-growth Evergreen Broad-leaved Forest in Central Taiwan

為了探討老齡林的植群變化，在12年後，複查2003年在北東眼山建立的1公頃動態樣區。從2003到2015年間，樹種的組成從57種增加為60種，5種自樣區中消失，新記錄8種；DBH≧1 cm的立木數量從3,809株增加為4,179株，淨增加率為9.7%，其中99.7%的新增立木DBH＜5 cm；胸高斷面積從768,461.86 cm²增加為804,777.11 cm²，淨增加率為4.7%。比較2003年與2015年的兩次調查，立木數量與胸高斷面積最優勢的前十種，發現樹種組成的相似度頗高，僅排名稍有變動，顯示在12年當中，樹種的族群結構略有變化，但樹種組成的改變很少，小徑木的大量增加顯示當地所形成的冠層孔隙大於單一樹倒所形成的孔隙，但因樹種豐富度、立木數量和胸高斷面積均沒有減少的跡象，且中、大級徑木仍持續有進級生長，故可推測林分在12年間處於相對穩定的狀態。 n order to explore the vegetation change of old-growth forest, the 1 ha forest dynamic plot established in Peitungyen mountain in 2003 was re-surveyed 12 years later. In 2015, the number of tree species increased from 57 to 60, 5 species had vanished and 8 species were newly recorded. The number of stems which were≧1 cm in diameter at breast height (DBH) increased from 3809 to 4179, the net increasing rate was 9.7%, and up to 99.7% of recruits were ＜5 cm in DBH. The basal area increased from 768461.86 to 804777.11 cm², the net increasing rate was 4.7%. Comparing the 10 most dominant species (in terms of stem number and basal area) between the 2 surveys, there was a high similarity of species composition, and the ranking only slightly differed. The result indicated that over 12 years, changes in the forest dynamics were mainly structural rather than compositional. A significant increment of small trees indicated that there were some medium-scale disturbances in Peitungyen mountain. According to the increments of species richness, stem number and basal area, coupling with medium and large trees had self-sustained growth, the forest was relatively stable in 12 years.