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Trees are subjected to multiple environmental mechanical loads and adapt the mechanical properties of their stems to an environment changing over time. Wind is one of the most important (Timell, 1986a). Wind loading can cause mechanical failure making the tree worthless in a commercial sense. A substantial amount of research on predicting wind throw and wind damage risk for commercial species has been conducted (Ancelin et al., 2004; Peltola et al., 1999; Mayer et al., 1989; Gardiner et al., 2000; Dunham and Cameron, 2000). These models do not investigate the structural failure within the tree, but attempt to identify how likely failure is to occur in a particular environment. Wind also has less obvious effects. Continued wind loadings from a prevailing direction can cause reaction wood production in order to compensate for this loading (Timell, 1986a).  While MFA controls the stiffness of the cell wall, basic density measures the amount of cell wall in the tissue. Therefore overall mechanical wood properties rely on both features.For a more detailed description of the TRP of MFA and density or these modelling and experimental attempts see ---Chapter 1---.  When investigating living trees from a structural standpoint other requirements need to be considered. Structural integrity of both greenwood and corewood have had little attention in literature at the scale of small cellular blocks. Investigating the TRP requires testing at scales small enough to separate corewood and outerwood. Most experimental work investigating the structural stability of whole stems is undertaken for use in failure prediction models for wind throw (statistical models such as HWIND and GALES, see ---Chapter 1---). Classical mechanics theories have been used, sometimes in conjunction with experimental data from tree pulling and wind tunnel experiments (Rudnicki et al., 2004; Peltola et al., 1999; Spatz and Bruechert, 2000). Neither take into account changes in material properties within the stem.