雪山翠池地區玉山圓柏林林分結構

Stand Structure of Juniperus morrisonicola Forest at Cuei-Chih Area in Mt. Shye

翠池地區玉山圓柏群落依形態及林分組成，可區分為矮盤灌叢、喬木林及交會帶之玉山圓柏林，本研究主要針對喬木型及交會帶之玉山圓柏林，進行林分結構的調查與分析。結果得知以負指數函數擬合喬木型玉山圓柏林，以及交會帶玉山圓柏、臺灣冷杉的直徑分佈，均屬反J型直徑分布。本研究發現喬木型玉山圓柏3個生長階段，以負指數分布函數模擬，適當反應出林分的相對密度及連續直徑階之間的削減速率，結果顯示初期階段削減速率最高、其次是晚期、中期階段削減速率低，而交會帶玉山圓柏亦有類似現象。透過密度—胸高直徑半對數圖，利用簡單線性迴歸驗證玉山圓柏林三種生長階段對數林分密度中，各生長階段之直徑階間的負斜率，可瞭解不同生長階段之遞減速率的差異，反映出老熟林不對稱U型死亡率之現象，即玉山圓柏為長壽型，且為長期處優勢之樹種表現，上揭研究結果可供後續對玉山圓柏林分動態研究參考。 Juniperus morrisonicola (juniper tree) forest community at Cuei-Chih Area in Mt. Shye of Taiwan, according to physiognomy and composition it can be divided into 3 categories of sites as following arbor forest, ecotone between J. morrisonicola and Abies kawakamii, and krummholz. In this paper, the class of diameter at breast height (DBH) of J. morrisonicola and A. kawakamii in the sample plots were surveyed. The results showed that the diameter distributions of trees including J. morrisonicola and A. kawakamii at arbor forest and ecotone sites were exhibited as inverse J-shaped. According to DBH size, both of J. morrisonicola individuals at arbor forest and econtone sites can be divided into 3 growth stages that were as early stage (ES), middle stage (MS) and late stage (LS) respectively. Here we can see a trend in diminished rate of these 3 growth stages, as highest diminished rate in ES, followed by LS and MS. The slope of simple regression of the density-diameter distribution on the Semi-log graph can be revealed the decreasing rate at different growth stages. It reflected the phenomenon of asymmetric U-shaped mortality in the J. morrisonicola forest stand and also suggested J. morrisonicola were the dominant species with long longevity at this area. All of results provide new information for further forest dynamic researches in the future.