This thesis explores the effects of wind on radiata pine (Pinus radiata) tree shape and wood stiffness, from the edge to the interior of a stand. The objective of the thesis is to detect, prior to felling, low stiffness trees or areas in a stand that due to wind will yield poor recovery of stiff lumber. The first three chapters review previous research. The first chapter focuses on the wood quality of radiata pine with special attention to stiffness, its causes and consequences. The second chapter introduces the principles of acoustic tools and how the forestry industry can use these to segregate raw material according to differences in wood quality. The third chapter describes the stress due to wind over a stand and how trees adapt internally and externally to wind. The next three chapter describe studies that were conducted in four narrow shelterbelts of radiata pine aligned perpendicular to the north-west winds. The chosen stands comprised three different age classes and two wind environments. At each stand, 30 transects were placed across the stand. At each transect, 20 trees were selected from the windward to the leeward edge of the stand. The outerwood stiffness of 2260 standing trees was assessed with the TreeTap acoustic tool. Results showed that stiffness and tree height increases with distance from the stand edge, while taper is reduced. The negative effect of wind on wood stiffness extends into the stand for a distance equivalent to one average tree height from both stand edges regardless of the age or location of the stand. The poorest trees were those located at the edges of the stand. High differences in outerwood stiffness between both sides of the stem were found, which increased with tree age and tree lean. A relationship could not be found between tree spacing to neighbours and tree outerwood stiffness. Knowledge of these low stiffness areas inside a stand will permit forest managers to develop different strategies to manage the variability in wood quality arising from wind. Future research might consider a sawmill study and further developing the methods utilized in this study in stands containing clonal trees.