Managing your forest land – Landowners Top-10 Frequently Asked Questions
US Forest Service, State and Private Forestry – Northeastern Area
Forest Stewardship Program
8. What should I do about the dead trees in my woods?
People love their forests and the trees. They understandably become concerned when a tree dies. In some situations dead trees should prompt you to contact a forester or Cooperative Extension educator for diagnostic assistance, but in other cases you can attribute tree death to natural and normal processes. In areas frequented by humans, dead trees can pose a hazard, but in other situations those trees are invaluable as habitat for a variety of wildlife. If you have sick trees in your yard or neighborhood, contact Cooperative Extension or a certified arborist to learn how to address the special circumstances of dead trees in populated areas.
Why do trees die?
Each year some of the trees in a forest will die. Tree death is normal. The trees in the forest are a
population
that is similar in some respects to human populations. In very young forests, the juvenile trees are subject to
environmental stresses
. Some trees don’t survive those initial stresses. As forests get older and the canopy closes the trees get larger and require more resources, but the amount of land and resources available for tree growth do not change. As trees begin to compete for resources, usually light, their growth slows, some are weakened, and some eventually die. As growth in a population stagnates, the weaker trees will succumb to insect or disease pests and die. In forests where there is competition for resources, there may be as much as 20 percent tree death, or one in five trees, before the average tree size will increase by 1 inch of diameter. This mortality may take 5 to 15 or more years, depending on the quality of the site and the age of the forest. In mature forests, some trees will die just because they have reached the upper end of their longevity. In forests of all ages, the number of trees that die each year will not be constant. Rather, the forest will have higher mortality in some years when an environmental event, such as drought, interacts with naturally weakened trees. In some cases, the environmental event triggers tree death that happens several years later.
Most forests in the Northeast and Midwest started on agricultural land, with many beginning in the late 1800’s and early 1900’s. Thus, the trees in a given forest are all approximately the same age, though of different sizes. Species such as black locust, pin cherry, paper birch, and aspen will live for only 40 to 100 years, even under ideal conditions. Thus, in forests that are 75 to 150 years old, death of these early successional tree species is common. Other species, like sugar maple, hemlock, and beech, can live up to 300 or 400 years.
Can I do anything to prevent my trees from dying?
You cannot prevent trees from dying, but you can influence which trees are most likely to survive. Through management treatments, such as thinning, you can provide increased sunlight, the most critical resource, to the desired trees by cutting the nearby less desired trees. In this way, you can enhance the growth and prolong the life of specific trees. In a previously unmanaged forest, this process is known as forest stand improvement (FAQ 4). In some situations, the cutting of trees (FAQ 5) can generate revenue while helping you, the forest owner, achieve a more productive forest. Selecting which trees to cut will likely require some assistance from professional foresters. Depending on your ownership objectives, you might also choose to do nothing and let tree death happen as it will.
Should tree death ever be a cause for concern?
A significant, sudden, and obvious pattern in tree death or loss of vigor, such as crown thinning or smaller than normal leaves, likely indicates a condition that requires additional professional assistance to guide your response. “Significant” means more than six or eight trees per acre. “Sudden” means that the tree death or vigor change occurs in the same growing season or from one growing season to the next. “Obvious” pattern means that you can describe the changes in the trees that relate to species, aspect, ages of trees, or geographic areas. Actually, if any two of these three conditions occur, you should seek assistance.
Where can I find more information?
Topic |
Recommended Web link |
General Tree Health Information |
|
Tree Health Publications |
|
National Plant Diagnostic Center |
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Northeast Plant Diagnostic Center |
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North Central Plant Diagnostic Center |
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Plant Disease Diagnostics in States |
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Ecological benefits of dead trees |