求翻译：我国生态公益林的研究起于20世纪90年代，随着林业生态效益的日益突出，一些林业工作者开始关注生态公益林。目前，在生态公益林建设中，在补偿问题、分类经营、经营措施体系建设和效益评价等方面研究的较多，而对林分树种的选择和林分结构调整等方面研究很少；二是生态公益林研究文献主要来自省市科研所、生产单位和管理部门，来自林业院校的研究文献相对较少，生态公益林基础理论研究的薄弱。是什么意思？

From the study of ecological public welfare forest in China than in the 1990 of the 20th century, with the growing of forest ecological benefit, some foresters are concerned about ecological forest. Currently, in ecological public forest construction in the, in compensation problem, and classification operating, and operating measures system construction and benefit evaluation, aspects research of more, and on forest min species of select and forest min structure adjustment, aspects research rarely; II is ecological public forest research literature main from provinces Research Institute, and production units and management sector, from forestry colleges of research literature relative less, ecological public forest basic theory research of weak.