Environment change of Sihu Lake in the past 450 years, southern China

In recent years, climate and environment changes since the Little Ice Age have become a focus in modern research. The paper selected the sediment (77 cm) of Sihu Lake, which was located in Guilin, southern China, as the research object and analyzed the karst wetland environmental changes within nearly 450 years. According to the vertical profile of indicators and geochemical elements in sediment core, the regional environmental evolution was divided into four stages. The former two stages were mainly influenced by Little Ice Age (1562-1895). The third stage climate has changed slowly. The fourth stage was mainly affected by human activities and global warming. The factor analysis of geochemical elements indicated that karst wetland regional environmental change was affected by four major factors. In the 53-77 cm stage (1562-1703), F1 (erosion factor), F2 (watershed runoff and diagenesis factor) and F3 (regional background factor) were reduced, indicating that it was in cold and dry stage of Little Ice Age. In the 20-53 cm stage (1703-1895), F1 and F2 increased, indicating that it was in cold and wet stage of Little Ice Age. In the 4-20 cm stage (1895-1987), F1, F2 and F4 (human activity factor) increased slowly, indicating that the climate was affected by global warming and more precipitation. In the 0-4 cm stage (1987-2007), F1 and F2 reduced and F4 increased, indicating the reduced precipitation, rising temperature and more impact of human activities. In addition, it was proposed that the Little Ice Age in Guilin District in southern China started in the 1560s and lasted until the 1895s or so.