Thinning is the process of tree removal in a forest stand to reduce tree density and tree-to-tree competition, encouraging increased growth of fewer, higher quality trees. Tree thinning is conducted every 10 to 15 years in replanted second-growth forests to remove the weaker trees, allowing more room and light for stronger trees to continue growing and to improve the overall health of the forest. Trees and branches that are removed during the thinning process are used for many paper and pulp-based products.

Insects, disease and excessive animal damage can be a threat to healthy, sustainable forests. Foliage and root diseases can spread among the forest killing trees. Insects, such as bark beetles, attack trees already under stress from some other factor. Temperature extremes, drought and high winds can damage broad areas of forest or create stress which makes trees more vulnerable to disease and insect infestations. Excessive animal damage can prevent young seedlings and vigorously growing new forests from reestablishing. Accurately diagnosing and managing these forest health threats is the first step to protecting forests from harm ensuring they will grow into the future.