The role of life history traits for bryophyte community patterns in two contrasting alpine regions

Abstract. Bryophytes are an important plant group with long-term dominance in alpine hab-itats. The alpine environment is however severe, and may restrict variation in bryophyte life history. This study examines the relationship between frequencies of bryophyte species and their life history traits between and within two alpine environments that differ in important environ-mental variables identified for bryophytes: 1) an oceanic region, with humid acidic soils (Setesdal) and 2) a sub-continental region, with more dry, productive, base-rich soils (Hol). A comparison between regions showed a higher frequency of base-demanding bryophytes in the sub-continental region. Sexual reproduction was more common among bryophytes in the oceanic region and these species also had higher indicator values for oceanic conditions and temperature as expected. Several life history traits were strongly correlated with bryophyte frequencies in the oceanic region—local species abundance increased in relation to shoot longevity, dioicism (mainly veg-etative reproduction), and high humidity indicator values, but decreased for species with asexual propagules (gemmae). No traits were correlated with bryophyte frequencies in the sub-continental region. The importance of life history traits in the oceanic region indicates that severe environ-mental factors override bryophyte community heterogeneity only in the oceanic, acidic region. A possible explanation for higher environmental stress favoring tolerant long-lived species with vegetative reproduction could be higher grazing pressure, which is also reflected in significantly lower cryptogam coverage and correspondingly larger area of open soil in the oceanic region