A Population Approach to Study Forest Stand Stability to Wind: Individual Tree-based Mechanical Modeling

Wind damage is a major disturbance interacting with forest development processes as well in natural forests as in managed forest. Models have been proposed to assess the risk of wind damage either with probabilistic approaches taking into account landscape, stand and tree attributes or with more mechanistic approaches at the scale of the tree. Allowing a precise description of the relations between tree characteristics and breakage or uprooting, mechanistic models are potentially interesting tools for testing the influence of various sylviculture strategies on damage. This work introduces a population model of wind damage based on the mechanical behaviour of all the individual trees in a stand. Using the Transfer Matrix Method of beams, this model allows wind and gravity loads, as well as mechanical state of stems to be well described. Applying the model on populations of Norway spruce trees, we try then to explore how damage is related to wind speed, and how damage at the population level can be predicted from the distribution of individual characteristics.