一、林木良种化的基本形势林木良种化是林业生产中最基本、最长远的建设,世界上一些发达国家,都把良种化作为科学营林、集约管理、提高森林生产力的重要手段。北欧的一些国家,早在40年代就开始选择优树,建立种子园。美国、苏联、日本、澳大利亚也在50年代相继开展了这项工作。有些国家生产上已广泛使用种子园、采穗(条)圃生产的种子和穗条造林,少数树种造林用种开始向使用第二代种子园的种子过渡,林木良种化工作已经取得了明 I. The Basic Situation of Improved Forest Tree Good forest tree planting is the most basic and long-term construction in forestry production. Some developed countries in the world regard improved plantation as an important means of scientific management of forests, intensive management and improvement of forest productivity. Some countries in northern Europe began to choose the best trees and establish seed orchards as early as the 1940s. The United States, the Soviet Union, Japan, and Australia also carried out this work one after another in the 1950s. In some countries, seed orchards and spike afforestation have been widely used in seed production in the production of seeds. Some species of afforestation in some species have begun to be switched to seeds using seeds of second generation seed orchards. The planting of trees has been completed