Wind effects on Tundra vegetation : insights from natural windbreaks in the Sub-Antarctic

Abstract

QUESTIONS : Wind is an understudied component of climate, with relatively few studies quantifying the effect of wind exposure on natural vegetation. Wind can, however, alter leaf microclimate, reduce soil water availability and physically damage plants, thereby influencing the growth of individual plants, with its effects potentially scaling up to affect plant community characteristics. The paucity of research assessing the relationship between wind conditions and plant communities' taxonomic and functional composition is a key gap in our understanding of environment–vegetation relationships in windy environments. LOCATION : Sub-Antarctic Marion Island. METHODS : We test whether vegetation characteristics, including vascular plant species richness, composition, cover and functional traits, differ between the windward and sheltered sides of natural windbreaks. RESULTS : Wind exposure did not strongly affect vascular plant richness, cover or composition, with larger differences in these responses occurring between sampling sites than between windward and sheltered microsites. Wind most strongly affected maximum plant height (both for individual species and for the community), with significantly shorter-statured plants observed in wind-exposed microsites. In contrast, most species' leaf traits were unaffected by wind exposure, with only 21% of species–trait combinations differing significantly between microsites. In those cases, plants experiencing greater wind exposure had lower leaf area, specific leaf area or leaf dry matter content, with changes in leaf thickness varying among species. CONCLUSIONS : Wind exposure did not strongly influence vascular plant community characteristics on Marion Island, apart from restricting vegetation height. Wind did, however, influence the occurrence and traits of some individual species, generally enhancing species avoidance or resistance to wind where its effects were significant. Broadly, these results indicate that wind can significantly influence plant size and some aspects of morphology, thereby reinforcing the need to explicitly consider wind as a potentially important climate variable, especially in habitats where wind is a prominent environmental factor and in areas where wind speeds are predicted to change.