PATTERNS OF BRYOPHYTE DIVERSITY IN PEATLANDS OF CONTINENTAL WESTERN CANADA

In continental western Canada, 62% of the 110 species found in 96 peat lands occur in Sphagnum-dominated bogs and poor fens, whereas 71% occu r in brown moss-dominated rich fens. Alpha (site) diversity is remarka bly uniform over the bog-rich fen gradient. Gamma (landscape) diversit y is highest in extreme-rich fens, which are the most variable of the five peatland types surveyed. Species richness at the site level is mo st 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 t ypes are examined individually, species richness in poor fens increase s with pH, in extreme-rich fens decreases with pH, and in peat plateau s, continental bogs, and moderate-rich fens remains relatively constan t regardless of pH. Feat plateaus consistently have greater species ri chness than continental bogs due to limited carpet and pool habitat he terogeneity in the latter. Twenty-five percent of the species were fou nd only once; these species are considered rare in the region. Sixty p ercent of these occurred only in extreme-rich fens. Habitat heterogene ity, plus pH or temperature in some peatland types, can be effectively used to predict site biodiversity.