The Distributions And Environmental Implication Of Modern Diatoms In Peatlands Of The Northern Of Greater Khingan Range

Diatom is a kind of eukaryotic algae that breed quickly.It is widely found in wetlands.The frustule of diatoms is highly silicified and it can be well stored in sediments.The valves of different genera diatoms are easy to be identified.The ecological width of diatom is narrow,so diatom is sensitive to environmental changes.The distribution of diatom communities is controlled by many environmental variables such as conductivity,water depth,salinity,nutrients,pH,temperature,and so on.Different species of diatoms can adapt to different habitats.When habitats change,diatom species that are sensitive to new environment may die rapidly and would be replaced by other diatom species that adapt to the new environment.Due to these characteristics,diatoms have been widely used in water quality monitoring,geological research,criminal technology,paleoenvironment and paleoclimatic reconstruction.In this paper,we study on the composition and distribution of diatoms in peatlands in the Northern Greater Khingan Range and the relationship between diatoms and environmental variables,and then accumulate diatom data for the diatom-environment factor database in research areas,in order to use diatoms to quantitatively reconstruct the paleoenvironment of the study area in the future.Peatlands are a very important type of wetland.The alpine region at high latitudes in northern China is one of the main distribution areas of peatlands.The Northern Greater Khingan Range is located at the northern margin of China and is one of the important peatland distribution areas in China.Because the Northern Greater Khingan Range is a monsoon fringe affected by the East Asian summer monsoon,the climate of the Northern Greater Khingan Range is unique and complex under the joint action of the East Asian summer monsoon and the Central Asian westerly wind.In this study,30 samples were selected from peatlands in the Northern Greater Khingan Range,and using the analysis method including the Detrended Correspondence Analysis,Principal Components Analysis,etc.to discuss the relationship between environmental variables and diatom distribution characteristics.Therefore,the main conclusions are as followings:?1?The environment of peatlands in the Northern Greater Khingan Range is generally acidic to weakly alkaline,and diatom diversity is abundant.A total of 107 species of 24 genera were identified,and there were few species of them are the Centricae diatoms.Most of them are the Pennatae diatoms,and the epiphytic diatoms and benthic diatoms accounted for a large proportion.Planktonic species occupy a very small proportion.The dominant genera are Navicula,Pinnularia and Eunotia,with 20,18,and 11 species,accounting for45.79%of the total.The dominant species are Caloneis silicula,Eunotia bilunaris var.bilunaris,Eunotia mucophila,Eunotia paludosa Grunow,Fragilaria capucina,Hantzschia amphioxys,Navicula radiosa,Nitzschia palea,etc.?2?The distribution characteristics and species diversity of diatoms were discussed in different vegetation types of peatlands.It can be found that there are differences in the structure of the dominant diatom species in the peatlands of different vegetation types.The species diversity of diatoms in the surface sediments of herbaceous peatlands is higher than which in shrub peatlands.?3?The relationship between diatoms in peatlands and environmental variables in the Northern Greater Khingan Range was studied.Through multivariate unconstrained and constrained ordering analysis,COD_Mn,pH and TN are the most important environmental variables that affect the species composition of diatoms in peatlands of the Northern Greater Khingan Range.The study of the relationship between diatoms and environmental variables in peatlands in the Northern Greater Khingan Range explains the sensitive indications of diatoms on pH and nutrient levels.For example,in this study area,Eunotia bilunaris var.bilunaris,Eunotia mucophila,Eunotia paludosa Grunow can be used to indicate the acidic water environment.Caloneis silicula,Fragilaria capucina,Hantzschia amphioxys and Navicula radiosa can be used to indicate the weak alkaline water environment.Navicula pupula can be used to indicate the medium-high conductivity,Nitzschia palea can indicate the degree of nutrients of the water,and Nitzschia terrestris is indicated to TN.