Bark stripping damage reduces timber quality through staining (due to fungal infection) and structural defects and ultimately reduces timber value and yield. Weakened stems may break and trees that are ring-barked will die from that point up.
Damage varies across sites and between years and is difficult to predict. Thin barked species such as sycamore, beech, oak, sweet chestnut, pine, larch and Norway spruce are most at risk with trees aged between 10 and 40 years being most vulnerable.
EnlargeGrey squirrel damage to 18-year old planted oak in a farm woodland planting scheme
EnlargeGrey squirrel bark-stripping to main stem of sycamore