Epibryic diatoms from ombrotrophic mires: diversity, gradients and indicating options

Abstract

The present study focuses on comparison of recent diatom diversity within the unique Central European ombrotrophic wetlands in two regions with contrasting levels of past atmospheric depositions (Jizerske hory Mts. and Jeseniky Mts.). Further, two methods of mire diatom sampling (squeezing and mineralization of the entire moss sample) are compared at the same localities to determine whether bryophyte herbarium specimens could be used for studies on the historical development of peat bog areas. There were a total of 47 diatom species at 59 sites within 13 ombrotrophic mires along the CzechPolish-German border areas. The regions did not differ in diatom species richness. The two-group pattern along the Axis 1 in NMDS ordination analysis did not correspond with the regional distribution. The inter-site variation in diatom assemblages was lower than the intra-site variation. The combination of three environmental variables (conductivity, pH, and height above water table – HWT) appears to be able to explain the diatom distribution patterns. No significant differences were found between the composition of diatom species of moss and squeezed samples. However, moss samples can be characterized by significantly greater species richness, most likely because the mineralization of the whole bryophyte minimizes the losses of diatom frustules caused by the squeezing method. These results allow us to reccommend herbarized bryophytes as a source of missing information on the sub-recent diatom diversity of mires.