我国北方飞播造林已经展开,仅1981年即播种约250万亩,播区分布在陕西、河南、河北、山西、内蒙、甘肃、宁夏、北京等省、市、自治区。目前选用的树种主要是油松。由于树种单一,人们对将来形成的纯林可能会产生病虫及火险不无担心。因此,造林 The aerial seeding afforestation in northern China has already started. In 1981, only about 2.5 million mu of seeding plants were sown. The seeding areas were distributed in Shaanxi, Henan, Hebei, Shanxi, Inner Mongolia, Gansu, Ningxia and Beijing and other provinces, municipalities and autonomous regions. The tree species currently used are mainly Pinus tabulaeformis. Because of the single tree species, people are not afraid of pests and fires that may form in future pure forests. Therefore, afforestation