Fruit trees, with their smaller size and shallower roots, are even less able to provide flood or landslide control.
原始的針葉林根又廣又深，抓土力強，樹與樹間又長滿灌木、草叢，鋪滿落葉枯枝，大大減輕雨水沖刷力；人工柳杉林排列得規規矩矩，但頂上覆蓋不如天然林，地上又露出大塊表土，水土保持能力自是小巫見大巫。