TRPs involving the samples which had properties that are more normally associated with Pinus radiata and had no anomalies produced the stems most resistant to breaking proportionality (LW →HS tends to perform best over all ages, closely followed by HS→HS, LW →LW , HS→LW and LS→HS). Stem breakage may have (partially) driven the development of wood structure changes, but this study indicates that a number of other TRPs may provide similar amounts of mechanical stability. The argument could be made that the constant profile HS→HS while appearing to be mechanically stable, may be more likely to become uprooted and break at a young age, hence there is an evolutionary driver away from this profile, the same argument could be made for the inverse profile of HS→LW .

Given the assumption that breaking proportionality is counter productive this indicates there is an advantage in using these wood types for stems which are under no unusual mechanical loads (e.g. strong prevailing winds). We can speculate to reasons why some TRPs are disadvantageous to survival. High stiffness in the center of stems may increase the chances of uprooting or breakage while the tree is young making high stiffness corewood profiles undesirable. High stiffness corewood is desirable for commercial forest operations where logs are graded on stiffness, as long as the trees can survive until harvest. The LS sample has an unusually low longitudinal tensile strength, this may be significant in why it does not perform well as outerwood.

By excluding the HS and LS samples as suitable corewood (due to their stiffness making them vulnerable to uprooting or breakage while young) only low stiffness corewood samples remain. Why high density high stiffness outerwood is most profitable for the stem is unknown, but it could be a result of a need to reduce bending in larger stems. Stiffer outerwood will require less material to reduce the deflection for a given load than lower stiffness material. The low stiffness low density corewood to high stiffness high density outerwood performed best in most scenarios, although closely followed by stems made entirely of low density low stiffness corewood. The low density low stiffness corewood stems exhibited a lot more deflection at given wind speeds than the other profiles, which may cause crown damage when situated near other trees.

Influence from growth stresses is apparent when comparing between model runs with and without growth stresses implemented. What growth stresses achieved which may be an advantage to survival is increase the height of the first points to break proportionality over all TRPs tested. The better performing TRPs both with and without growth stresses break proportionality highest within the stem, however when growth stresses are introduced poorer performing profiles which typically break low on the stem, break at a similar height to the better performing profiles. At high wind speeds better performing profiles exhibit a lower proportion of failed points within the stem, and the amount of failed points is much more constant at different heights in the stem than poorer performing profiles. Adding growth stresses accentuates differences between good and poor profiles, with poor profiles typically having more points fail lower in the stem than higher while better performing profiles have a more even distribution in the lower two thirds of the stem, with the maximum number of failed points near half the total height of the stem. The concentration of first failure around half the height of the stem when growth stresses are included may on the other hand indicate a less obvious mechanical advantage of growth stresses. A tree breaking at the base either dies, or must reproduce a substantial amount of biomass to become competitive again, however if a stem snaps at half its height, there are likely to be a number of branches which could take over as new leaders reducing the time it takes to become light competitive again. Multiple leaders may have an advantage if wind breakage is common due to the lower force on each leader from the canopy.

Pinus radiata grow in both forests and open plains. The two regimes experience different environmental impacts because of their soundings. A tree in a dense forest is sheltered from wind, however must compete strongly for light, whereas a tree in the open must withstand higher wind loads, however does not have to compete for light. Light competition and shelter from wind results in stems with higher slenderness ratios as they put more biomass into growing taller to out compete other trees along with higher crowns with lower crown radii. Open grown trees have lower slenderness ratios to withstand the higher wind speeds they are subjected to as they grow. Crowns form lower on the stem, with larger radii because they are not restricted by the surrounding trees. When the two regimes are compared open grown stems are substantially more resistant to wind loadings, even with their larger crowns.

The constant stress hypothesis \citep{mattheck_wood_1995} argues that trees grow in such a way as to preserve constant surface stress. Some of the results presented here provide some support for this idea, particularly that stems with natural TRPs have a more consistent profile of failed points in the vertical direction than non natural profiles do.

The TRP and the wood properties it consists of have a substantial influence on the structural stability of the stem. For a given tree the variability in the wind speed required to break proportionality has a range of 10 m/s. By comparison, for a stem with the TRP (LW →HS) growth stresses and slenderness only cause half this variation in the wind speeds required to break proportionality, indicating the TRP plays a significant roll in a stems ability to withstand wind loads. Given the magnitude of changes in both stocking and growth stresses, both of these effects also need to be considered.