The invasion of alien species also tests the strength of mangroves. For example, Yang Juan said that the invasion of Spartina alterniflora led to the degradation of mangrove mudflats in Zhangjiangkou, Xiao Yun, Fujian. A graduate student from the Institute of Agricultural Resources and Ecological Environment of Nanjing Agricultural University wrote in a paper in 2008: "Twenty years ago, there were about 150 hectares of mangroves in Feiluan Bay, Ningde City, Fujian Province, and now there are only more than 100 plants scattered in the endless Spartina alterniflora."