Seasonal Change Of Diatoms And Climate Response In Recent 800 Years Of Douhu,Fujian

In recent years,with A series of environmental problems intensified,like global warming,sea level rise,ice retret,desertification,decreasing biodiversity.And attracts many attentions from scholars and government officers.The research of global change has become a hot topic at home and abroad.Diatoms as a most important biological proxies in lacustrine depositit and it is widely used in paleoclimate and paleoenvironmental reconstruction.As a result of the advantage of sensitive to environmental change,siliceous shell is easy to preserve and easy to indentified.Plenty of research shows that with the global warming,there has been a significant change in assemblages and biodiversity of diatoms in high latitude,temperate,and many high altitude regions of northern hemisphere.However,it is still unclear how the diatoms in subtropical regions respond to global warming.This study selects two-year seasonal diatom samples from Douhu Lake and 83 core sediment diatom samples as research objects to explore the seasonal variation of diatoms in Douhu,Fujian,and the characteristics of the combination of diatoms in Douhu Lake since the Little Ice Age,attempting to explain the subtropics.The response pattern of diatoms to the global warming in mountain lakes in the area.The following research results and understanding have been obtained through the analysis of laboratory sediment diatoms,production,identification,statistics,and diatom species and combinations:1.30 genus and 115 species(include varietas)of diatoms were identified from 44 samples;34 genus and 106 species(include varietas)of diatoms were identified in the sediment from the DH-C core of Douhu.The dominate species were similar between seasonal and sediment samples.2.The changes in the dominant species of seasonal diatoms in Douhu are mainly controlled by changes in water temperature.3.According to the change of relative abundance of diatom species,three significant diatom zones and two sub-zones were recognized.Based on the changes of diatom assemblage,we discussed the main diatom species response to chimate since the Little Ice Age and the response of diatom to global warming.4.The Simpson and Shannon-Winner index show that the biodiversity of diatoms of Douhu Lake is high in cold period and low in warm period.With the global warming,diatom biodiversity is increasing.