论文部分内容阅读
松林是我国主要用材资源和林化资源之一,其总面积约4000万 hm~2,占全国有林地面积的32%和针叶林面积的76.3%。松毛虫是我国最严重的森林害虫,堪称不冒烟的森林火灾。70年代以来,我国松毛虫发生总面积约为每年150—200万 hm~2。松毛虫灾害的发生,其后果是严重的,其一是直接经济损失。据估计,我国每年由此造成的立木损失和松脂损失分别为1000万 m~3和5万 t,按1990年国家不变价格计算,两项资源的价值损失合计每年达7.5亿元,如果将松枝和针
Pine forest is one of the main timber resources and forest resources in China. Its total area is about 40 million hm ~ 2, accounting for 32% of the national forest area and 76.3% of the coniferous forest area. Dendrolimus is one of the most serious forest pests in our country, a forest fire that does not smoke. Since the 1970s, the total area of dendrolimus occurred in China is about 1.5-200 million hm ~ 2 per year. Pine caterpillar disaster occurs, the consequences are serious, one of the direct economic losses. It is estimated that the annual loss of turrets and loss of turpentine caused by our country are 10 million m 3 and 50,000 tons respectively. According to the constant price of the state in 1990, the total value loss of the two resources amounts to 750 million yuan a year. Pine branches and needles