一、采种:要想多造杨树林,就必须要培育大量的种苗。过去只依靠用插条造林和埋干造林,但是有些地方因为缺少种条,不能大规模地营造杨树林。同时,这些方法虽然简单易行,但是成活率低,树木长到中年,便开始衰弱,树干容易破裂和烂心,所以寿命比 First, seed collection: To make more poplar, we must cultivate a large number of seedlings. In the past, they relied only on afforestation and trunk planting, but in some places they can not build poplar forests on a large scale because of lack of planting. At the same time, although these methods are simple and straightforward, the survival rate is low. When the trees grow to middle age, they begin to weaken, the trunk is easily broken and rotten, so the life-span ratio