A strut will be stronger in compression and stiffer in bending if the high modulus material is on the outside. Stress near the center (neutral axis) is low. Denser woods like spruce, bass or birch are good in the case of concentrated loads. Otherwise balsa will be lighter for a given strength.
A common approach is to design the strut to pull out in a crash without damaging the strut attachment point or surrounding structure in the wings or fuselage.