(一)积极开展林木育种工作林木育种工作,自五十年代以来,特别是近十年来在国外得到了空前规模的发展。这项工作已成为提高林木生产率、保证林分稳定性等方面的重要措施,并在生产实践中取得了卓越成果。如意大利选育的欧美杨“Ⅰ—214”既对当地危害极大的春枯梢病有抗性,生长又迅速,9年生时每公顷蓄积量达330立方米,超过一般杨树产量的40％,经济 (I) Actively carry out forest tree breeding Forest tree breeding has enjoyed an unprecedented scale of development abroad since the 1950s, especially in the past decade. This work has become an important measure in improving the productivity of forest trees and ensuring the stability of the stands, and has achieved remarkable results in production practices. For example, “I-214”, a poplar from Italy, was both resistant to the locally devastating spring blight and grew rapidly. At nine years, its stock volume per hectare reached 330 cubic meters, more than 40 %,economic