Community-level functional traits of alpine vascular plants, bryophytes, and lichens after long-term experimental warming

Abstract

We measured community-level traits of vascular plants, lichens, and bryophytes in an alpine Dryas octopetala L. heath in Finse, Norway, after nearly two decades of experimental warming by open-top chambers. We hypothesized that under warming (1) vascular plant traits would shift from resource conservative towards more resource acquisitive, and (2) lichen and bryophyte traits would shift to those associated with drier conditions, due to increased evapotranspiration. Both hypotheses were not supported, as vascular plant nitrogen concentration decreased, whereas carbon to nitrogen ratio increased with warming, indicative of a less resource acquisitive strategy, and lichen specific thallus area and water holding capacity were unresponsive. Bryophyte specific shoot length increased, and carbon concentration and water holding capacity tended to decrease under warming, concurrent with increased vegetation height and litter cover indicating stronger competition from vascular plants. Intraspecific variation was most important for vascular plant and lichen traits, whereas species turnover was the main driver of bryophyte trait variation. This indicates that bryophytes may be affected more strongly by future warming than vascular plants and lichens in our study system. We highlight the importance of studying traits of different primary producer groups simultaneously, as they may respond differently to the same environmental changes.