论文部分内容阅读
辽宁北部、西北部6个市20个县(区)的“三北”防护林体系工程建设,从1978年开始,历经十几年,到1990年底完成造林保存和合格面
The construction of the “Three Norths” shelterbelt system in 20 counties (districts) of 6 cities and towns in north and northwest of Liaoning Province started from 1978 and after more than 10 years, the afforestation preservation and qualified surfaces were completed by the end of 1990