Phenotypic variation at different spatial scales in relation to environment in two circumpolar bryophyte species

Morphology, physiology and biomass in two widespread bryophyte species, Hylocomium splendens and Racomitrium lanuginosum, were studied to examine the extent to which different species exhibit similar phenotypic variation patterns within and across regions. Analyses of nine morphological variables, chlorophyll content, nitrogen content, C/N ratio and biomass were conducted in samples from five sites in two geographically separated and climatically different regions, Iceland and northern Sweden. Both species exhibited large between-site variation in morphology, physiology and biomass, but within-site variation in morphology was substantially higher in Hylocomium splendens than Racomitrium lanuginosum. Morphological patterns were partly similar, partly different between the species, indicating that the two species respond morphologically to external factors on different scales. The lowest concentrations of chlorophyll and nitrogen were found at the same sites for both species, while the site of highest concentration was not the same. In Hylocomium splendens, chlorophyll content was positively correlated with biomass. Many of the observed relationships between morphological, physiological variables and biomass were species-specific. Our results demonstrate that the two bryophytes exhibit different phenotypic responses to environmental variation