Changing wind climate as a result of climate change

 

Britain is already exposed to a severe wind climate, as such the current way in which forestry is managed,  particularly in the uplands is already largely adapted to cope with extremes of wind. However, strong winds can effect trees in a variety of ways:

• Mortality of young plants through desiccation or toppling
• Restriction of growth
• Effects upon tree form through branch and leader loss
• Mortality through windthrow and wind snap.

Wind damage - individual tree

Wind damage - forest stand

Future predictions for wind

Making accurate predictions on how the wind environment may change the future is very difficult. Predictions of the changes in the wind climate are among the least certain of the UKCIP02 scenarios, they do, however, indicate:

• An increase in the number of deep depressions crossing the UK
• A more southerly storm track
• A shift in the seasonal pattern of windiness, resulting in an increase in autumnal windiness and a decline in summer windiness

The consequences of these predicted are:

• A slight increase in mean windspeed
• A possible increase in the frequency of gales
• The increases in winter windspeed may be largest in the south.

However, it must be noted that the magnitude of these predicted changes is generally less than the inter-annual variability that we would expect to occur naturally.

What would be the potential impact of these changes?

A slight increase in mean windspeed or a shift in seasonally is unlikely to have an observable impact on woodlands or forestry. The likelyhood is that their effects will be masked by those associated with the other impacts of the changing environment. An increase in the frequency of intense storms could potentially have a significant effect. Mean windspeed is not necessarily the most important element of windspeed - the distribution of windspeed, and also wind direction during storm events are equally important when making predictions of the effect of a changing wind climate on woodland and forestry. This is further expored in Bulleting 125.