How can trees stand up during years using extremely slender beams : the smart and regulated processes of adaptive wood formation.

Tree stems are incredibly slender structures that are faced with great mechanical constraints. Their mechanical performance is widely based on a smart regulation of wood formation during growth. We will show how trees perceive their mechanical environment and respond by auto-stressing processes that allow movements and increase safety. We will discuss the choice of relevant mechanical variables (forces, bending moments, strains, stresses …) to build phenomenological laws of perception-response.