Boundary trees are trees on the boundary between neighbouring lands. Neighbours’ conduct relating to boundary trees has been legislated since 1896 when the Ontario Tree Planting Act was enacted. The purpose of the Act was to encourage the planting and growing of trees. It allowed for municipal grants to support the planting of trees along highways, public lanes, alleys, places, or squares or on the boundaries of adjacent farms or lots. It also defined the ownership of the trees. They would belong to the owner of the land adjacent to the highway or lane and they would be the common property of both land owners if trees were planted on boundary lines with both owners’ consents.
The 1896 Act was revised many times over the years, and consolidated in 1950 in what was then called the Trees Act. Today, boundary trees are governed by section 10 of the Forestry Act. This section provides that an owner of land may only plant trees on the boundary between two properties with the consent of the adjoining land owner. It also provides that every tree whose trunk is growing on the boundary between adjoining lands is the common property of the owners of the adjoining lands. The clear meaning of this provision is that the trunk cannot be removed by one neighbour without the consent of the other neighbour. The Act provides that a land owner who injures or destroys a tree growing on the boundary between adjoining lands without the consent of the other land owner is guilty of an offence. A conviction could lead to a fine. However, if there are a lot of boundary trees cut down, the court may order the owner to replant the trees, in the manner and within the time that the court considers appropriate and to adequately maintain the replanted trees in the manner the court considers proper.
The Forestry Act does not cover every case of boundary trees. Some trees involve the phenomenon of “tree trespass” which is alive and well in rural Ontario. For example, there are “border trees” whose trunks are solely on one property at ground level, but whose roots encroach into a neighbour’s lands, or whose canopy of branches invades the air space above the neighbour’s lands. There is clear authority in the court decisions for the principle that a land owner is legally entitled, without notice to or consent from a neighbour, to cut those branches and roots of a neighbour’s border tree which extend onto his or her property or air space although such action may kill the tree.