衡阳县地处湖南省中部偏南,紫色砂页岩山地面积大,分布广,物理风化强烈,土层瘠薄,水土流失严重。改造和利用紫色砂页岩地是衡阳县退耕还林工程的重点所在,是 Hengyang County, located in the south of central Hunan Province, purple sandstone shale area, widely distributed, strong physical weathering, barren soil, soil erosion is serious. Renovation and utilization of purple sand shale is the focus of the project of converting farmland into forestry in Hengyang County