PATTERNS OF BRYOPHYTE DIVERSITY IN PEATLANDS OF CONTINENTAL WESTERN CANADA

In continental western Canada, 62% of the 110 species found in 96 peatlands occur in Sphagnum-dominated bogs and poor fens, whereas 71% occur in brown moss-dominated rich fens. Alpha (site) diversity is remarkably uniform over the bog-rich fen gradient. Gamma (landscape) diversity is highest in extreme-rich fens, which are the most variable of the five peatland types surveyed. Species richness at the site level is most highly correlated with habitat heterogeneity. Climatic factors ave not as important; however, habitat heterogeneity (46%) and temperature (15%) together explain 61% of the variation. When the five peatland types are examined individually, species richness in poor fens increases with pH, in extreme-rich fens decreases with pH, and in peat plateaus, continental bogs, and moderate-rich fens remains relatively constant regardless of pH. Feat plateaus consistently have greater species richness than continental bogs due to limited carpet and pool habitat heterogeneity in the latter. Twenty-five percent of the species were found only once; these species are considered rare in the region. Sixty percent of these occurred only in extreme-rich fens. Habitat heterogeneity, plus pH or temperature in some peatland types, can be effectively used to predict site biodiversity.