Earth surface processes drive the richness, composition and occurrence of plant species in an arctic–alpine environment

Abstract

AbstractQuestionsAre earth surface processes (ESPs) important determinants of species richness, composition and fine‐scale distributions? Do differentESPs have similar effects on these vegetation characteristics?LocationSaana massif, northwest Finland (69 °N).MethodsVascular plant species occurrences, five environmental variables (related to soil conditions and topography) and fiveESPs were surveyed across 960 1‐m2quadrats in arctic–alpine tundra. Community composition was examined using non‐metric multi‐dimensional scaling (NMDS), while species richness and individual species occurrence were modelled usingGLMs,GAMs and boosted regression trees.ResultsThreeESPs (solifluction, fluvial activity and nivation) were strongly related to community composition, with only soil moisture and mesotopography exhibiting stronger correlations withNMDSscores.ESPs significantly improved the accuracy of species richness models based on soil conditions and topography, with solifluction and fluvial processes having the largest individual contributions. Solifluction and fluvial activity also increased the predictive power of species distribution models, with these processes often being as influential on occurrence patterns as some of the traditionally utilized direct and resource variables. Arctic–alpine species generally responded positively toESPs, with boreal species showing the opposite trend.ConclusionsThis study, the first to examine the impacts of several independentESPs on multiple vegetation characteristics, demonstrates thatESPs are primary drivers of species fine‐scale distributions, species richness and community composition in arctic–alpine plant communities.ESPs varied in their effect and relative influence, and thus severalESPs need to be considered when examining species‐ and community‐level properties of vegetation.