Linking small-scale topography with microclimate, plant species diversity and intra-specific trait variation in an alpine landscape

Background: Small-scale topographic complexity is a characteristic feature of alpine landscapes, with important effects on alpine plant distribution. Aims: We investigated the links between small-scale topographic complexity and resultant microclimatic heterogeneity, vascular-plant species richness and beta diversity, and realised niche width and trait variation of some target species. Methods: We recorded temperature and soil moisture within 10 sites (40mx40m) of differing topographic complexity in alpine terrain at Finse, Norway (N 60 degrees 36MODIFIER LETTER PRIME, E 7 degrees 33MODIFIER LETTER PRIME). Plant species occurrence and traits of target species were recorded in 16 sample plots at each site. Results: Sites differed significantly in microclimatic heterogeneity, and topographically rough sites were always more heterogeneous than flatter ones. Greater species richness and turnover was associated with greater microclimatic heterogeneity, and rough sites contained 15-55% more species than flatter ones. Plant species had on average wider realised niches when growing at rough sites. Individuals of Bistorta vivipara, but not those of Luzula spicata, tended to exhibit greater phenotypic variation at rough sites. Conclusions: Rough alpine terrains create small-scale variation in microclimate, promoting species richness and beta diversity. In the event of climate change, small-scale microclimatic heterogeneity might allow plant species to escape from regional climate change by short-distance migration to local micro-refugia. This study suggests that the opportunity for such responses would be greater in topographically complex terrains.