Tree Thinning is the selective removal of internal branches evenly throughout the tree to reduce the density of the crown. However, it does not change the overall size or shape of the tree. Thinning would not normally be carried out on conifers, so it is generally confined to deciduous broadleaf trees. Thinning is designed to reduce damage that could result from crown resistance to strong winds. Thinning may be carried out to admit more air and light into and through the canopy. Thinning opens the foliage of a tree, reduces weight on heavy limbs, and helps retain the tree’s natural shape. The volume of the branches to be removed will normally be expressed as a percentage of the whole crown.