This process requires specialised servicing and selective removal of stems and branches. This allows better lighting and airflow at the crown of the tree and is very important to the rejuvenation process.
Thinning is the selective removal of live branches to reduce crown density. The center and left portion of the tree to the right has been thinned. Thinning, of various types, is the most commonly-practiced method of pruning on mature trees in some regions. Thinning allows wind to pass through or into the pruned section of the crown, which can temporarily improve durability in a storm or sunlight penetration to the ground. Perhaps the best use of crown thinning in the landscape is to reduce mechanical stress on selected limbs from gravity, wind, ice, or snow on branches with structural defects such as cracks, cavities, and hollows, and on codominant, overextended, or long branches.