Signs of a Healthy Forest

A tree health checklist can help you determine how healthy your forest is and what action you can take to improve woodland health.

When you go in for a checkup, the doctor doesn’t just look at one part of your body—he or she evaluates every system to make sure you’re OK.

Giving your woods a checkup is very similar. You have to check every system within your forest to know if the whole is in balance. That means inspecting individual trees, looking at the diversity of the whole forest and the plants and animals that live in it, and studying the cycles at play in your woods. Together, these elements give you a picture of your forest’s overall health.

Let’s start with individual trees. What signs should you look for?

Your Tree Health Checklist

Feel free to print off this checklist:

What you see What it means
  • Ragged leaves with holes
  • Insects are feeding on the leaves
  • Black or brown leaves
  • Stem or leaf disease; could also be sign of frost or salt damage
  • Spots or bumps on the leaves
  • Insects and mites could be damaging the tree
  • Twisted or malformed leaves
  • Herbicides, insects or disease are damaging the tree
  • Leaves are changing color before fall
  • Trunk or root damage; drought or pollution could also be the cause
  • Branch decay
  • The tree may have unhealed wounds
  • Peeling or broken bark, or holes in the bark
  • Trunk wound, canker disease, or damage caused by humans or animals
  • Dying branches on one side of the crown
  • Root decay, root injury or internal stem disease, insect attack
  • Canker (a dead section of trunk or branch)
  • Fungal infection
  • Splits in the tree
  • Broken branches, wind damage or exposure to severe or dry conditions
  • Hollows in the tree
  • Water entering the tree through old wounds and fueling fungal wood decay
  • Fungi or mushrooms growing on the tree
  • Internal decomposition of the wood by fungi
  • Green or brown spots on needles
  • Air pollution
  • Red needles
  • Possible insect infestation


When going into your woods for their checkup, bring some colored chalk to mark trees as healthy or sick as you go. Note that 10 percent or more of the tree should be affected to count it as damaged or diseased.

As you can see, any one sign could mean a variety of things, and only a professional forester can know for certain what’s to blame. So if you notice several trees in your stand have signs of disease or damage, consult with a professional to determine your next steps.

But the health of individual trees doesn’t tell the whole story of your forest. The diversity of your woods—the mix of plant species and habitats there—is just as important.

Find out More

For help assessing and supporting the health of your woods, consult with


*contains information adapted from the Project Learning Tree Secondary Grades 9-12 Module Focus on Forests

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