Crown thinning is the removal of a portion of smaller branches, usually at the outer crown, to produce a uniform density of foliage around an evenly spaced branch structure. It is usually confined to broad-leaved species. Crown thinning does not alter the overall size or shape of the tree. Material is removed systematically throughout the tree, and does not exceed more than a 30% loss of foliage. Common reasons for crown thinning are to allow more light to pass through the tree, to reduce wind resistance and to reduce weight.