Epiphytic diatoms and their relation to moisture and moss composition in two montane mires, Northeast China

Abstract

Moss-inhabiting diatom communities were studied in two montane mires on the western flank of the Changbai Mountains (Northeast China). A total of 119 taxa belonging to 44 genera were found in 33 samples. Height above the water table (HWT), pH and Sphagnum-species were found to be three significant factors controlling diatom distribution using redundancy analysis. HWT was found to be the primary factor influencing diatom distribution. Eunotia paludosa var. paludosa, Luticola mutica var. mutica and Hantzschia amphioxys were typical species of dry hummocks. Samples from wet hollows were characterized by Eunotia steineckii, Microcostatus mac­ eria, Adlafia bryophila and Eunotia mucophila. In addition, a small but significant portion of the variance in diatom data can be explained by the sole effect of pH or bryophyte coverage. Chamaepinnularia hassiaca was observed in samples with relatively high pH values and abundant Sphagnum palustre. Furthermore, significant correlations were observed between the valve length of E. paludosa var. paludosa and moisture parameters (i.e. water content and HWT), indicating that diatoms would acclimate to moisture limitation by decreasing cell size. This study revealed that both moss-inhabiting diatom communities and diatom cell sizes were sensitive to moisture changes and both of them should be useful proxies for paleohydrological reconstruction in mires.