Liu Zongyuan is the secretariat of Liuzhou, Liuzhou Liu secretariat, that is to say, himself. Planting willows in Liujiang is his behavior of uploading willows in Liujiang. To put it simply, Liu Zongyuan planted willows by the Liujiang River.
Others are "nothing can be seen three hundred miles away, only vague Woods and mountains, and nine winding rivers"