Habitat distribution models, spatial autocorrelation, functional traits and dispersal capacity of alpine plant species

We evaluate the potential influence of disturbance on the predictability of alpine plant species distribution from equilibrium-based habitat distribution models. Firstly, abundance data of 71 plant species were correlated with a comprehensive set of environmental variables using ordinal regression models. Subsequently. the residual spatial autocorrelation (at distances of 40 to 320 in) in these models was explored. The additional amount of variance explained by spatial structuring was compared with a set of functional traits assumed to confer advantages in disturbed or undisturbed habitats. We found significant residual spatial autocorrelation in the habitat models of most of the species that were analysed. The amount of this autocorrelation was positively correlated with the dispersal capacity of the species, levelling off with increasing spatial scale. Both trends indicate that dispersal and colonization processes, whose frequency is enhanced by disturbance, influence the distribution of many alpine plant species. Since habitat distribution models commonly ignore such spatial processes they miss an important driver of local- to landscape-scale plant distribution.