Trees are among our most valuable natural assets, offering shade, improving air quality, supporting wildlife, and enhancing the beauty of our communities. Yet one of the most important parts of a tree is also the most overlooked. Its root system. Protecting a tree’s critical root zone (CRZ) is essential to maintaining its health and longevity.
The critical root zone refers to the area of soil surrounding a tree where the majority of its roots are located. These roots absorb water and nutrients, store energy, and anchor the tree in place. Contrary to common belief, most tree roots grow within the top 30–60 centimetres of soil and extend far beyond the tree’s canopy. Because they lie close to the surface, they are especially vulnerable to disturbance.
Construction and landscaping activities pose the greatest threat to the CRZ. Soil compaction from heavy machinery, trenching for utilities, and changes in soil grade can all damage roots or reduce their ability to access oxygen and water. Even seemingly minor changes, such as adding a layer of soil or paving over root areas, can stress a tree over time. The effects may not be immediate. Trees often decline gradually, showing symptoms years after the damage occurs.
Protecting the critical root zone during development and maintenance projects is therefore crucial. Installing tree protective fencing around the CRZ, limiting vehicle traffic, and avoiding excavation near the trunk are simple but effective measures. When work within the root zone is unavoidable, consulting an arborist can help minimize harm.
Many municipalities reinforce these practices through by-laws and construction guidelines that require tree inventories, protection plans, and monitored safeguards on-site. These regulations ensure that tree preservation is built into project planning and execution, helping reduce damage and maintain long-term tree health.
Healthy roots mean a healthy tree. By respecting and protecting the critical root zone, we help ensure that trees continue to thrive, providing environmental, economic, and social benefits for generations to come.
