Wind Effects on Tundra Vegetation: Insights From Natural Windbreaks in the Sub-Antarctic

Prepared by Nicola Marneweck, Leandri de Kock, Janine Schoombie, Michelle Greve and Peter C. le Roux

When we think about climate, we usually think of temperature and rainfall. But if you have ever felt the difference between a sheltered and exposed site on a windy day, you know that wind matters too. For plants, wind can affect growth and survival by drying soil, reducing the rate of photosynthesis, and physically damaging stems and leaves. These effects on individual plants likely add up to influence whole plant communities. However, there is surprisingly little research assessing the impact of wind on vegetation in windy environments. 

We determined the impact of wind exposure on plant community characteristics and morphological traits on the chronically windy sub-Antarctic Marion Island situated in the Roaring Forties, halfway between South Africa and Antarctica. The island’s landscape offers a natural experiment in which large boulders act as windbreaks, leaving one side exposed to strong dominant westerly winds and the other side sheltered. We compared vascular plant species richness, cover, composition, height and leaf traits between these wind-exposed and wind-sheltered sides of natural windbreaks across the island.

Wind had a clear effect on plant height, with plants in wind-exposed sites being significantly shorter than those at sheltered sites. Most species’ leaf traits showed no clear response to wind exposure, but the few species that did respond generally expressed traits to avoid or withstand wind stress. Wind exposure, however, did not strongly influence vascular plant community characteristics. This was a surprising result, as previous work on Marion Island found wind stress to be an important driver of vascular plant richness and cover. This suggests that subtle patterns could be missed when comparing only two distinct levels of wind exposure.

The findings of this study show that wind can be a key climatic factor influencing plant size and some aspects of morphology. It is likely that wind has been an important selective pressure on plants in this chronically windy environment, and it is unclear whether wind would play an even greater role in less wind-adapted environments, particularly those where wind speeds are predicted to increase in the future. Since wind can also interact with other climate variables, understanding exactly how and why wind shapes vegetation – directly and indirectly – is an important priority for predicting how plant communities will respond to future changes in wind.

This is a plain language summary for the paper by Marneweck et al. published in the Journal of Vegetation Science (https://doi.org/10.1111/jvs.70171)