一、人天混合更新的必要性所谓人天混合更新,即是充分利用自然更新能力又适当与人工更新相结合,以达到培育一代质量较高新林的目的。在黑龙江省林区的大多数采伐迹地上,都能自然地发生数量不等的天然幼苗和幼树,每公顷少则几千株,多则几万株甚至更多。实际调查了解,黑龙江省森工企业的山上林场,每年的人工更新几乎都是在有林地上进行的,虽然也有一部分是在新采伐迹地上进行的,但几年后也都长满了天然幼树, I. The Necessity of Mixed Regeneration between Man and Nature The so-called “people-days mixed update” is to make full use of the ability of natural regeneration and properly integrate with manual updating so as to achieve the goal of cultivating new generation of forests with high quality. Naturally, natural seedlings and saplings of varying heights naturally occur on most of the logging sites in the Heilongjiang Forest Region, ranging from a few thousand plants per hectare to tens of thousands or more. The actual investigation shows that the forest farms in the forestry enterprises in Heilongjiang Province are almost entirely reforested on the woodlands every year. Although some of them are also carried out on newly deforested land, they are also covered with natural seedlings after a few years tree,