Life-form adaptations and substrate availability explain a 100-year post-grazing succession of bryophyte species in the Moricsala Strict Nature reserve, Latvia

Bryophyte species composition, richness and life-form distributions were studied in a succession after termination of land-use as meadows and pasture in the Moricsala Strict Nature Reserve. Detailed lists of bryophyte species in various vegetation types, which were produced in the early 1900s by Karl Reinhold Kupffer, were compared with those prepared from 2006 to 2010 to determine changes in species composition. Colonisations and extinctions of bryophyte species and life forms could be explained by increases in available substrates (living trees, dead wood, ground layer disturbance patches), and increasingly shaded conditions. In each forest type, the species diversity (alpha diversity) increased, but the differences (beta diversity) between the types decreased. The total number of bryophyte species recorded in the studied forest area increased from 110 to 134 and that of rare (including Woodland Key Habitat indicator species) and protected species from 14 to 21 species. Twenty species were lost during the forest succession, but most of these species still occur within the reserve in open habitats. Life forms such as small compact cushions and short turfs tended to be lost during the forest succession, while smooth and rough mat life forms were better adapted to the new conditions and increased in richness.