應用地面光達技術於臺灣杉人工林之疏伐監測

Using Terrestrial Laser Scanning System to Monitor Thinning Effects for Taiwania cryptomerioides Hayata Plantations

詹于萱(Zhan Yu-Xuan)

指導教授 ： 陳建璋 ； 魏浚紘

國立屏東科技大學/農學院/森林系所/碩士(2019年)

https://doi.org/10.6346/NPUST201900183

摘要

疏伐(Thinning)為人工林經營過程中重要的撫育作業之一，進行疏伐作業可營造健康的立木生長空間，進而產生林分結構(Stand Structure)的變化，對於人工林立木生長具有正面影響。如何準確性的量化疏伐作業對林分結構變化之影響，為疏伐作業對立木生長效益評估之重要議題。地面雷射掃瞄系統(Terrestrial Laser Scanning System, TLS)因其具有高精度、高密度及高機動性等特性，且可獲取物體的三維形貌，近年來被大量應用於森林資源調查。本研究應用TLS技術，以荖濃溪事業區之臺灣杉(Taiwania cryptomerioides Hayata)人工林為試驗材料，透過Weibull機率密度函數模擬林分結構探討林分生長狀態，再配合競爭指數探討如何調整林分直徑分布結構，以促進林木生長。本研究於臺灣杉40年生人工林設置15個樣區，研究結果顯示，經由K-S適合度檢定，Weibull機率密度函數可有效描述樣區之直徑分布。目前林分結構呈現正偏歪分布的樣區，林分內小徑木數量偏多，林木競爭情形嚴重，為增加林木的持續生長，在經營上須進行疏伐作業，以營造立木的最大生長效益。本研究利用11個樣區38個疏伐率進行疏伐模擬，應用三參數推導疏伐率與相關尺度關係式：p=99.4203-1.6253R，計算各直徑階疏伐株數配合競爭指數模擬疏伐木之選取，經模擬疏伐後計算留存木之平均最適株距為3.34±0.06 m，可作為荖濃溪事業區下層疏伐作業，各直徑階疏伐株數估算及單木留存株距之依據，研究結果亦可供經營管理者配置疏伐木及立木空間距離，以及訓練疏伐人員如何選取下層疏伐之疏伐木之參考。

關鍵字

Weibull機率密度函數 ； 疏伐作業 ； 林分結構 ； 地面光達

並列摘要

Thinning is an important tending operation in the plantations management, especially has positive impacts for the tree growth. The stand structure which has been subjected to thinning operations will be changed the stand structure and to create a healthy growth space. However, how to do accuracy assessment in the effect of thinning is an important issue in forest management. In recent years, the Terrestrial Laser Scanning System (TLS) has been widely used in forest resource surveys to collect forest characteristics, due to its high precision, high density and high mobility. In this study, we used TLS to analyze the growth of Taiwania cryptomerioides Hayata plantations in Launonshi working circle. Using Weibull probability density function to simulate the stand structure, growth and how to adjust the diameter distribution of the stand to promote the growth of the forest were discussed. The results were checked the goodness of fit by K-S test, and show that the Weibull probability density function can effectively describe the diameter distribution of the 15 experimental plots, which were set up in the 40-year-old plantation of Taiwania cryptomerioides Hayata. The diameter distribution of plots is positively skewed due to the number of small-diameter woods in these plots is a great amount, and the trees have a competition each other, thinning operations must be carried out and to promote the tree growth benefits for this stand. This study used 38 thinning rates in 11 plots for thinning simulation, the relationship between the thinning rate and the relevant scale was deduced by three parameters: p=99.4203-1.6253R, and the average optimum plant spacing of the retained wood after simulated thinning was 3.34±0.06 m. The result can be used as a reference for the estimation of the number of thinning plants of each diameter class, and the distance between the single wood and the remaining plant in the thinning area of the Launonshi working circle of Taiwan Forestry Bureau. The results of the study are also available for managers to allocate the distance between the felling wood and the standing timber, and to train the thinning personnel to select the thinning wood for the thinning from below.

並列關鍵字

Weibull probability density function ； thinning ； stand structure ； Terrestrial Laser Scanning System (TLS)

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