- 期刊
溪頭試驗地柳杉人工林材積生長的長期變化
Long-term Volume Growth Changes of Sugi (Cryptomeria japonica D. Don) Stands in Xitou Tract
摘要
本研究以臺大實驗林溪頭營林區觀音樹湖以及溪頭湖柳杉人工林生長量之歷年調查成果，分析其生長模式並探討在長輪伐期經營下的材積生長趨勢。結果顯示，最大材積收獲輪伐期分別為林齡39年及55年。由林分結構及歷年株數與每ha胸高斷面積總和得知，林分密度會因自我疏伐而下降，但林分仍維持相當的鬱閉狀態。為有效促進林木的生長，因此需要依據不同的林分結構與林分環境，制訂適當的疏伐作業措施，以期獲得優質之大徑木，妥善運用森林資源。研究資料也顯示：風災對於立木移除具有隨機性，對林分的後續發展也有強烈的影響，因此風災後的撫育工作顯得格外重要。林分在長時間生長下，可逐漸彌補風災造成的材積損失量，但當林分逐漸進入衰老期且蓄積逐漸往大徑木集中時，老齡林枯損則會顯著影響林分蓄積量的變化，因此老齡林經營對於永續的森林資源利用有關鍵性影響。
並列摘要
This study is aimed to explore long-term trends of volume growth of Cryptomeria japonica D. Don stands in Xitou tract. Long-term observation data from two permanent plots in Guanyin-Tree Lake and Xitou Lake of the Experimental Forest National Taiwan University were used for the analysis. Results showed that the maximum volume yield rotations for each plot were estimated to be at the age of 39 and 55 years. Stand densities decreased due to self-thinning of stands while the current canopy closures were still in good situation. In order to effectively promote the volume growth of old sugi forest, it is necessary to have a suitable thinning for the stands based on the stand structure and the stand environment. This will be able to improve tree quality and the effective use of forest resources. It is also observed that typhoon removed forest trees randomly. So, tending forest is very important after typhoon's damages. After a relatively long-term period of growth, the damaged volume will be recruited. Nevertheless, the growth rate and mortality of the forest stand will be significantly reduced and/or increased respectively when the forest stands get old. Suitable managements of old forests play a critical role in the sustainability of the appropriate forest resources.