Differences in richness of vascular plants, mosses, and liverworts in southern Norwegian alpine vegetation

Background: Theories regarding patterns of species richness often focus on single factors such as stress, productivity and disturbance, but these have recently been challenged. Vascular plant species richness is also frequently used as a surrogate for richness in other species groups, but species richness relationships have rarely been studied in alpine areas.
Aims: To establish the relationship between environmental variables and species richness of vascular plants, mosses and liverworts, and to identify common patterns across these different groups.
Methods: A stratified random sampling procedure was followed to select sample plots (4 m2) from ecologically different homogeneous alpine vegetation stands. The data were analysed by Pearsson correlation analysis, regression analysis, stepwise regression analysis, principal correlation analysis (PCA), and redundancy analysis (RDA).
Results: 210 vascular plants, 152 mosses and 89 liverworts were identified from 304 plots. Humped (quadratic) responses were found for some species groups only in relation to date of snowmelt and total vascular plant cover. Vascular plant and moss richness were strongly positively correlated with soil richness.
Conclusions: Richness of vascular plants and mosses, and mosses and liverworts, may be used as surrogates for one another in the alpine vegetation plots studied, but vascular plant richness cannot be used as a surrogate for liverwort richness.