一、前言林分的生长发育,以至收获,主要靠自然力的作用;但林分密度调整,作为一项人为促进措施。无疑是具有效力的。这个问题,很早就引起了各国林业工作者的重视,並从理论和应用上开展了试验研究。例如,六十年代初,美国和加拿大的林学家曾从概念上对所发表的许多学术论文作过论证。 I. Foreword Forests grow and develop, and even harvest, mainly by the role of natural forces; but the stand density adjustment, as a man-made promotion measures. Undoubtedly effective. This problem has long aroused the attention of forestry workers from all over the world and has carried out experimental research on theory and application. For example, in the early 1960s, forestry scientists in the United States and Canada have argued many of the published academic papers conceptually.