Lala and to Chilan in Ilan County. This great wall of trees acts as a vital "safety valve," regulating the flow of water into the Shihmen Reservoir, the Tanshui River and the Lanyang River, on which millions of people in northern Taiwan depend for the water they drink. The coat of green which clothes the mountains intimately affects water quality and soil stability in Taoyuan, Hsinchu, Miaoli and Ilan Counties.
由這一片殘存的蠻荒檜木原始林往北延伸，到桃園拉拉山與宜蘭棲蘭，檜木連結成綠色長城，是北台灣百萬人賴以維生的石門水庫、淡水河、蘭陽溪的安全閥，一衣帶水，桃竹苗、宜蘭水土系統的穩定緊緊受其牽動。