Ecological distribution of modern diatom in peatlands in the northern Greater Khingan Mountains and its environmental implications

Relationships between diatom assemblages and environmental variables in peatlands of the northern Greater Khingan Mountains are helpful for understanding the indicative significance of diatoms to environment changes, and potentially provide a reference for environmental monitoring and paleoenvironment reconstruction in the edge of monsoon region. In this study, we analyzed modern diatom assemblages and their relationships with environment factors in 30 surface samples from shrubby-herbaceous and herbaceous peatlands based on ordination analysis. Benthic and epiphytic Pennatae diatoms are mainly ecological types, whereas planktonic Centricae diatoms are relatively fewer. The most diverse genera are Pinnularia and Eunotia. Eunotia paludosa and Achnanthidium minutissimum dominated in shrubby-herbaceous peatlands, while Navicula minima and Fragilaria capucina dominated in herbaceous peatlands. The diatom community structures are different in different vegetation types and the diatom species diversity in herbaceous peatlands is higher than that in shrubby-herbaceous peatlands. CODMn and pH are the most important environmental factors affecting diatom species composition and diversity. Eunotia bilunaris, Eunotia mucophila, and Eunotia paludosa can be used as indicators of acidic water environments. Caloneis silicula, Fragilaria capucina, Hantzschia amphioxys, and Navicula radiosa can be applied to indicate the weak alkaline conditions. Eunotia bilunaris and Eunotia paludosa can indicate low conductivity, while Sellaphora pupula indicates the medium-high conductivity. Fragilaria capucina and Navicula radiosa can indicate oligotrophic habitats.