Diversity patterns in relation to the environment in alpine tundra ecosystems of northern Norway

Abstract

We analyzed diversity patterns of alpine tundra ecosystems along environmental gradients. We hypothesized that alpine diversity is affected by climate at local and regional scales, nutrient availability, soil moisture, and disturbance related to herbivory. In all, 232 samples in 11 study areas in Troms and Finnmark counties were analyzed with regard to α- and β-diversity of vascular plants and lichens. Relationships between α-diversity and environmental variables were analyzed by regression trees, β-diversity defined as species turnover was investigated using indirect ordination methods. Sites with non-acidic soil parent material showed highest species densities. Lowest species numbers were typical for extreme topographic positions. Heavily grazed samples showed less species numbers and coverage percentage of vegetation. The number of graminoid species was found to be highest in areas of high grazing pressure. We concluded that α-diversity was controlled by growing season, snow cover, pH, soil moisture, disturbance, temperature, and precipitation, stressing the importance of multi-factorial approaches in diversity studies. Determinants of β-diversity were predominantly local environmental conditions, whereas regional conditions were less important. © 2008 Regents of the University of Colorado.