光達技術應用於人工林之經營與監測

Application of LiDAR System for Monitoring and Management of Artificial Forest

魏浚紘(Chun-Hung Wei) ； 陳朝圳(Chaur-Tzuhn Chen)

《航測及遙測學刊》 20卷4期 (2016/06) Pp. 231-250

https://doi.org/10.6574/JPRS.2016.20(4).1

摘要

本研究利用地面光達探討如何以非破壞性方式，調查及監測森林樣區之立木三度空間資訊，及如何應用光達系統所量測之資訊應用於人工林經營。以自動化方式獲取疏伐作業所需之林分性態值資料，包括樹高、胸高直徑、樹冠高、立木位置圖等資料，並評估地面光達於人工林測計之可行性。結果顯示，透過地面光達系統確實可正確獲得立木資訊，對於永久監測樣區而言，以光達系統之不同拍攝位置，可消除掃瞄的遮蔽效應，藉由高密度的點雲資料，可直接測量立木樹高與不同樹幹位置之直徑，而單位體積之點雲資料量不同，會影響立木直徑推估之結果。而地面光達所獲得之樹高與樹徑之3D資料，可進行 非破壞性之區分材積估算，並建立立木材積式。光達點雲資料之空間分布，所推估之樹冠高程模型，以樹冠高度之灰階值統計，藉由二值法所訂之閥值，可將林木與地表背景分離，獲取林冠孔隙之平面及垂直資料，此一林冠孔隙資訊可供為孔隙動態監測研究。地面光達所建立之林木測計、立木競爭指標、林冠孔隙及與疏伐監測資訊，可更準確的量化疏伐效益及增加林木狀態變化之資訊，對於人工林經營可提高森林資源調查效率，及擴充森林資源監測資訊。

關鍵字

森林經營 ； 疏伐作業 ； 地面光達 ； 三維雷射掃瞄 ； 林分性態

並列摘要

In this study, using 3D scanning Light Detection and Ranging (LiDAR) systems, which are the non-destructive methods, to investigate and monitor individual trees in artificial forest sample areas. Using ground-based LiDAR and traditional field survey data to obtain individual tree characteristic values which included tree height, diameter at breast height, canopy height, tree location map and evaluated the feasibility of ground-based LiDAR data in artificial forest areas. Results showed that the accurate information from the ground-based LiDAR system in permanent sampling plots, and different scanning stations could decrease occlusions. By using high density point cloud data, the height and diameter at different height of the tree could also be measured directly by the LiDAR systems. Different number of point cloud affected the accuracy of diameter. Results also showed that the systems could establish tree volume model non-destructively with tree height and DBH data obtained from ground-based LiDAR. Using threshold value to classify gap fraction, results showed that were accurate. Therefore, the results could be used to analyze the horizontal and vertical canopy structure, it was beneficial for the monitoring of plot dynamics in forest areas. Ground-based LiDAR could be used to determine tree measurements, tree competition and canopy gap which solve the problems of quantification and spatial research and also help with the stimulation of thinning operations. Results of this study were beneficial to artificial forest management and improved the forest resource inventory methods.

並列關鍵字

forest management ； thinning operations ； ground-based LiDAR technology ； 3D laser scanning ； stand characteristics