The facts that Taiwan is highly mountainous, consists chiefly of weak sandstone shale, is located in an earthquake belt and in the path of typhoons, and receives three times as much rainfall as the world average--all increase the amount of forests it requires for adequate soil and water conservation.
全島有四分之三是山地，其中容易崩塌的坡度（廿一度以上）佔了一半；地質又以不堅固的砂頁岩為主；加上位在颱風路徑及地震帶上；且雨量集中夏季，年平均高達二千四百卅公釐，是世界平均雨量的三倍… …，水土容易流失，要做好土保工作，所需森林比例相對提高。