五、楂口开得正。 1.慎重开下楂: 开下楂(也叫安全楂),就是利用“重物一侧悬空下垂”的原理,在人为倒向的下侧,用斧、锯开一个缺口。树被伐的过程中,其重心向下楂口下沉,使之按人为倒向徐徐倒下。在一般情况下,下楂口的深度是伐根直径的三分之一或四分之一,高度约为深度的二分? Five, hawthorn is right. 1. Cautiously open the hawthorn: open hawthorn (also known as safety hawthorn), is the use of “heavy side hanging droop” principle, in man-made down to the side, with an ax, saw a gap. In the process of tree cutting, the center of gravity sinks down to the mouth of the hawthorn, causing it to fall backward by man. In general, the depth of the haw throat is one-third or one-fourth the diameter of the root, and the height is about two in depth.