Exposing wind stress as a driver of fine-scale variation in plant communities

The effects of temperature and precipitation, and the impacts of changes
in these climatic conditions, on plant communities have been investigated
extensively. The roles of other climatic factors are, however,
comparatively poorly understood, despite potentially also strongly
structuring community patterns. Wind, for example, is seldom considered
when forecasting species responses to climate change, despite having
direct physiological and mechanical impacts on plants. It is, therefore,
important to understand the magnitude of potential impacts of changing
wind conditions on plant communities, particularly given that wind
patterns are shifting globally. Here, we examine the relationship between
wind stress (i.e. a combination of wind exposure and wind speed) and
species richness, vegetation cover and community composition using
fine-scale, field-collected data from 1440 quadrats in a windy
sub-Antarctic environment. Wind stress was consistently a strong predictor
of all three community characteristics, even after accounting for other
potentially ecophysiologically important variables, including pH,
potential direct incident solar radiation, winter and summer soil
temperature, soil moisture, soil depth, and rock cover. Plant species
richness peaked at intermediate wind stress, and vegetation cover was
highest in plots with the greatest wind stress. Community composition was
also related to wind stress, and, after the influence of soil moisture and
pH, had a similar strength of effect as winter soil temperature.
Synthesis: Wind conditions are, therefore, clearly related to plant
community characteristics in this ecosystem that experiences chronic
winds. Based on these findings, wind conditions require greater attention
when examining environment-community relationships, and changing wind
patterns should be explicitly considered in climate change impact
predictions.