Maintain or improve the ability of forests to resist pests and pathogens: Increase species and structural diversity

Adaptation Strategies and Actions

Maintain or improve the ability of forests to resist pests and pathogens: Increase species and structural diversity

Adaptation type:

Land and forest stewardship or restoration

Strategy:

Maintain or improve the ability of forest to resist pests and pathogens

Action

Increase species and structural diversity
Dead trees are a natural part of healthy forests. Standing dead trees, called snags, and downed logs serve as very important habitat that is often lacking from many forests. However, when a large portion of a forest declines, that can reduce the enjoyment and benefit of that forest.

Pests and pathogens will be increasingly prevalent as climate conditions change. Forests can naturally adapt to these changes through slow changes in species composition, but you can help by encouraging high species and structural diversity in your forest. Forests that only have a handful of species and that contain trees of all the same age and height often suffer the most from pest or pathogen invasions. Diversifying tree species and the range of tree ages and sizes in your forest helps to spread risk and doesn't put all of your "eggs" in one basket. This diversification will help to make your forest more resistant to pests and pathogens by limiting the host trees.

Diverse age classes in a beech-birch-maple forest. Photo credit: Anthony W. D'Amato

Fungal pathogens also disproportionately damage trees that are already under stress, such as during drought events. Thinning your woods will decrease tree competition for sun, water, and growing space and increase the vigor of trees that remain.

Damage to trees and soil from a poorly executed timber harvest can also increase stress. Work with a consulting forester to plan your harvest and develop a strong contract to minimize impacts from the timber harvest. In most cases, it is not feasible to remove affected trees, however, depending on the fungal pathogen or pest, it may be important to remove affected trees to limit its spread (for example, Asian longhorned beetle). Contact your local state service forester if you have any questions.