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\section{Introduction}  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 MicroFibril Angle (MFA) contributes to 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. Wood properties within 'normal' stems tend to follow what is known as the Typical Radial Pattern (TRP) --- ref to size- and age related...---. \citep{meinzer_frederick_2011}.  MFA reduces while density increases from the pith to the periphery of the stem. Note that this is not universal and some species and individuals do not necessarily follow the pattern completely. Over the last century or so there have been a number of suggested explanations for why trees grow with the TRP observed. The mechanical hypothesis which is investigated in this study, asserts that the TRP is a result of the tree needing to respond to different mechanical loadings from its environment as it grows. For a seedling, being highly flexible could be important in order to bend out of the path of animals and reduce wind and snow loads. However when the tree grows and a significant size is reached along with a large canopy greater stiffness could be an advantage in outerwood as bending becomes difficult due to the stem diameter. Note that there are other hypotheses, for a good review see Meinzer et al. (2011). The purpose of this paper is to investigate the effect of the TRP of MFA and density on the ability to withstand wind loading.