Small ones and big ones: cross-taxon congruence reflects organism body size in ombrotrophic bogs.

The monitoring of currently changing bogs has triggered a need to improve our understanding of correlations between different taxa. We analysed the cross-taxon congruence of six contrasting groups of organisms (vascular plants, bryophytes, fungi, diatoms, desmids and testate amoebae) in permanent plots located in differently polluted summit ombrotrophic bogs in two regions of the Czech Republic. In the suboceanic region, whose bogs are more uniformly polluted, the congruence was generally lower. Vascular plants, bryophytes and fungi showed the same gradient structure, while three groups of protists behaved rather independently of one another. In the subcontinental region where recent aerial liming created a new pH gradient, the congruence was generally higher. The main difference among different taxa corresponded clearly with body size and life span (microorganisms versus macroorganisms), conforming the previous results of a faster response of microorganisms to the artificially created pH gradient. Generally, vascular plants, bryophytes and fungi provided similar information, while diatoms behaved most independently. The major division among the study taxa coincided with body size rather than with nutrition or propagule size. [ABSTRACT FROM AUTHOR]