Modeling Human Impact on the Distribution of the Only Existing Species of Euryale

Human activity has a profound impact on the distribution of a number of species, especially those with ecological and economic importance. Euryale ferox Salisb., an annual macrophyte native to South, Southeast, and East Asia, has long been cultivated for its fruits and seeds in north India and east China. However, classified as endangered in Japan, South Korea, Kashmir Himalaya, and Taiwan, China, E. ferox is the relict species of the genus that has been under both natural and human disturbances. Under rapid global change, how human activity affects the distribution of E. ferox in Asia remains unknown. To answer whether humans promote or limit its distribution, we compile by far the most complete set of 404 records of occurrence of E. ferox from the Russian Far East and 10 countries in Asia, and build species distribution models using machine learning methods. The results show that temperature of the coldest month is negatively associated with the occurrence of E. ferox, while the positive association between it and anthropogenic nitrogen deposition is more important for explaining its distribution. Its distribution is projected to decline by 8.3%-16.7% under four climate change scenarios in the 2050s if the levels of human activity remain unchanged. Given the genetic, ecological, medicinal, and economic importance of E. ferox, it is necessary to conserve its wild populations under global change.