林分可通过主伐更新为同龄林或异龄林。同龄林就是所有林木的年龄都相当接近的林分,异龄林则由两个以上龄级的林木所组成。无论更新为那种林分,都要通过一定的采伐方式。皆伐、母树法和伞伐都可更新为同龄林。若要更新为异龄林,只有通过择伐。现在让我们看看这四种方式的优缺点。择伐是采伐成熟林木,通常是最老或最大的植株,单株采伐或小块采伐。采伐是不定期地、相当经常地进行,以保持林 Stands can be upgraded to the same age or aged forest by primary cutting. The same age forest is the age of all trees are very close to the stand, different age forest is composed of two or more age groups of trees. No matter what kind of forest is renewed, it must pass certain logging methods. Clear cutting, tree and umbrella can be updated to the same age forest. To update to an ancestral forest, only through selective cutting. Now let us look at the advantages and disadvantages of these four ways. Selective cutting is the harvesting of mature trees, usually the oldest or largest plant, logged per plant or cut. Logging is carried out irregularly and quite often to preserve the forest