Tree Markings in Ontario

Have you ever noticed a painted mark on a tree in a forest? Or seen a sign posted to a tree in your neighbourhood? Do you know what these tree markings are for? There are a few different reasons, but lets look at a few of them.

Tree Markings in Ontario

The 15 x 5 cm yellow blazes mark the main managed trails in Warbler Woods, while the white blazes note where the Thames Valley Trail merges with it


The tree markings you may be most familiar with are the painted rectangles marked on trees in forests. They are trail blazes and are typically white, yellow, green, or blue. Blazes appear on the side of the tree in the direction you are heading. They note the path of a trail you are on, the direction it is heading in (if it is turning right or left), and whether side trails verge off of it. You can also find them on posts, utility poles, and other handy surfaces. Typically, the next blaze is visible from the previous blaze. When you see more than one blaze, it signifies that two path converge for a distance.

In London, Ontario, the City has erected signs to designate appropriate trees as wildlife trees


You also may have come across small, yellow signs on London-area trees marking them as Wildlife Trees. The signs state;

“Do not cut or disturb. Saved for food, shelter and nesting.”

These trees have been selected as having value for local wildlife living in the area. They may be live or dead, with a cavity or without, but for whatever reason, they have appropriate characteristics to make them a valuable home, food source or nesting space for wildlife living in the area.


This brings us to silviculture and the Tree Marking profession.

Silviculture is the branch of FORESTRY that deals with establishing, caring for and reproducing stands of trees for a variety of forest uses including wildlife habitat, timber production and outdoor recreation. It requires a knowledge of how various TREE species grow under particular conditions of SOIL, CLIMATE and spacing.

Definition from The Canadian Encyclopedia

In Ontario, we require anyone assessing trees on Crown land to be an official Tree Marker. A 4-day Ontario Tree Marker course is offered through Forests Ontario and the Canadian Institute of Forestry. In it, participants learn various Ontario Forestry Management practices; amongst other things, which trees to cut or leave. Wildlife benefits, seed potential, growth, health and product potential are all taken into consideration. Because a carefully considered forest is a healthier forest.

Tree Markers decide which trees may be viable for timber, which ones could offer cavity and nesting sites for wildlife, and which ones pose a risk. They work on Crown Land and private, with individual trees and larger tree stands, but ultimately their aim is the same—to retain biodiversity within the forest. And as such, that entails marking trees to cut, retain, or define the working area. The manner in which the markings are applied is important as well, for a few reasons. Whomever comes to cut the trees then knows which one to cut and subsequent audits determine if the correct trees were actually cut down.

“One of the most important aspects of tree marking is the correct application of paint to the selected tree. Two distinct paint applications are required; a top mark and a butt mark… ”

Section 7, Pg 203, Administering a tree marking program; Ontario Tree Marking Guide

Those paint colours and meanings are;

  • YELLOW or ORANGE – trees to remove for harvest
  • RED – boundary line/reserve marking
  • BLUE – trees to retain, e.g., crop tree, trees for wildlife
  • BLACK – when mistakes are made, cover up with black paint
  • WHITE – research plots

Sound confusing? Ultimately, it helps keep our forests healthy for forestry, recreational use, and wildlife. And those certified to assess trees have an important job in maintaining Ontario’s forests. So whether you know what the marks on a tree are for or not, know that they are there for a reason. Someone assessed the tree and its surrounding area with many factors in mind. Those tree markings are vitally important for the health of our forests, so be happy in the knowledge that someone is looking after them.

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