Fine‐scale persistence of boreal bog plants

Abstract. Persistence, or the tendency of a species to remain in its original position without colonizing new sites, is studied for 24 species on the ombrotrophic Northern Kisselbergmossen in SE Norway. Data sets comprise presence/absence in 436 sample plots (16 cm x 16 cm) and 6976 subplots (4 cm x 4 cm) analysed with a 5‐yr interval. Persistence was calculated for both spatial scales, and the observed values were compared with null models of completely random presence/absence of species. Species characteristics (plot occurrences and persistence) were related to depth to the water table and species optima along ecologically interpreted DCA ordination axes. The observed persistence was significantly higher than predicted from the random model for all vascular plants and cryptogams at both spatial scales. All taxonomic groups showed higher persistence at the sample plot scale than at the subplot scale. No general relationship between persistence and depth to the water table was found, but for the cryptogams there was somewhat higher persistence for the less peat‐producing species. The persistence of the vascular plants depended on ramet longevity, growth form and vegetative mobility. In general, the observed persistence of most cryptogams was high, probably because of their perenniality, low growth rates and high reproductive output. Differences in growth‐form and life history, as well as the higher number of occurrences, are the most likely reasons for somewhat higher mean persistence of hepatics and Sphagna than of vascular plants at the subplot scale.