生態單元之劃分，為林地分級之首要工作。為符合林地分級不同尺度之需求，多尺度生態單元之區劃已成為一重要的研究課題。本研究旨在解決林地分級有關生態單元尺度的問題，供全國性林地分級之用。研究過程以荖濃溪事業區為試區，視集水區為一基本生態單元，應用數值地形模型，發展出全自動化多尺度生態單元粹取法，可自動判釋河川級序及搜尋出水口，並以不同河川級序定義集水區界，自動地達成多尺度生態單元之粹取工作。研究結果顯示，應用數值地形模型，自動判釋河川級序及搜尋出水口，進而定義集水區界之作法，確實為粹取多尺度生態單元之最佳方法，可符合林地分級不同尺度之需求，供日後全國性林地分級之 Delineation of ecological units is an important task for forest land classification. Considering forest land classification based on different scales, delineation and integration of multi-scale ecological units have become an important issue for resource managers. In this research, the objective was to investigate the scale of ecological units for the use of nationwide forest land classification. The Launonshi working circle of the Taiwan Forestry Bureau was chosen as the study site, and a watershed was treated as a basic ecological unit. In view of ecological units based on different scales, a method using a digital terrain model was developed to automatically delineate multi-scale ecological units. The watersheds, which form the multi-scale ecological units, were delineated based on streams of different orders. The results indicate that automatically identifying streams of different orders and searching for the outlets of watersheds using the digital terrain model is the best method for delineating multi-scale ecological units. In addition, it is very helpful for nationwide forest land classification when considering management practices on multiple scales.