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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 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. --introduce TRP here --- ref to size- and age related...---  Over the last century or so there have been a number of suggested explanations for why trees grow with the typical radial patterns (TRP) 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 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,see Chapter 1 for more details or  for a good review see Meinzer et al. (2011).This thesis endeavours to in investigate the mechanical hypothesis in further detail by including the ability for material properties to vary within the stem to represent the TRP. The approach used is to construct a finite element model of a tree with different radial patterns and subject it to wind loadings. In ---Section 3.2--- the required mathematical and physical principles are briefly introduced along with the implementation of these principles to this particular problem. Finally comparisons are discussed between the various wood structure profiles.  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. 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. ---ref--- being the only known example where all nine orthotropic elastic material constants have been reported for core and outer wood.