1·In 1978, China began a nationwide tree-planting programme known as the Three North Shelterbelt Forest Programme, also known as "the Great Green Wall".
1978年，中国开始了一项全国性的植树计划，即三北防护林计划，也被称为“绿色长城”。
2·Poplar is the important tree species for shelterbelt and timber forest in our country. However, rapidly and fiercely-spreading by disease and pest has led to tremendous economic losses.
杨树是我国重要的防护林和用材林树种，但病虫害的迅猛发展造成了巨大损失。