当前我国北方林区木材生产的作业方式通常为两种:一种叫常年流水作业,另一种叫季节性作业。从目前的发展趋势看,季节性作业比重越来越大。据伊春林管局统计,在所属的16个林业局中,1980年有两个林业局是季节性作业,即乌敏河、上甘岭局。1981年又有双丰、桃山林 At present, wood production practices in the northern part of our country are usually two kinds: one is called perennial flow operation, the other is called seasonal operation. Judging from the current development trend, the proportion of seasonal operations is increasing. According to the statistics of Yichun Forestry Bureau, among the 16 forestry bureaus involved, two forestry bureaus in 1980 were seasonal operations, that is, the Wumin River and Shangganling Bureau. In 1981 there Shuangfeng, Peach Hill