Tree thinning a tree's canopy increases light and air below the tree. The practice is also useful to keep a tree in a certain growth habit, prevent it from getting too tall, or keep limbs from getting invasive. Whatever the reason, canopy thinning is a selective pruning practice that should be done when the plant is dormant for best results.
The is thinning of a tree canopy reduces the weight of the branches and stabilizes and strengthens the tree. Heavy thinning should be discouraged, as it can encourage the formation of unwanted growth, but light thinning will encourage new needle or leaf growth, which provides increased photosynthesis and improves a tree's health.
Light pruning to open up the canopy and bring in more light is mostly done on the exterior parts of the tree. This is where heavy growth has caused limbs to branch out and shade lower part of the Tree. Only the tips of the outer growth are taken back with proper canopy thinning.
Excessive interior limb removal makes the plant unstable and weak. The only interior material that should be removed are the dead or broken limbs and stems. Thinning should keep the tree in as natural a form as possible and focus on making a balance of branches to form a sturdy base.