Wind damage in forests associated with fragmented landscape in Aquitaine, France

Abstract

On 24 January 2009 approximately 37 million m3 of maritime pine trees were damaged by storm Klaus in the south-western region (Aquitaine), France. This region consists of more than 90 % private forest ownership and the mean area of parcel is 14 ha, but 75 % of the forest owners have a less than 4 ha parcel. This shows that a large number of small forests with differing management plans are found in the region, but the direct relationship between such a fragmented landscape and wind damage has not been clearly demonstrated. The aim of our research was to find out how fragmented landscapes during storm conditions might affect the degree of wind damage in the Aquitaine region. First, we created a map showing the location and area of wind damage caused by storm Klaus in addition to the land-use type using aerial photos taken after the damage. The landscape was classified as four types of forest based on height and stem density, residential areas, open fields, water, and we also determined three degree of damage. The map was subsequently used to determine the neighbouring land-use type and difference of height between the particular land-uses. Wind speeds during the storm were estimated using data from the Application of Research to Operations at Mesoscale (AROME), developed by Météo France. A logistic regression analysis described that the difference of the windward height (west), land-use change, and maximum wind speed during the storm were significantly related to more than 50% of wind damage in forests. Further analysis will be conducted to understand the influence on the levels of wind damage of wind speed variation and intensity during the storm, and the spatial variability of land-use