Designing with Trees in Mind: All about the roots

Tree roots are shallow and extensive. Image courtesy City of Toronto

By Alex Satel, MFC, and Philip van Wassenaer, B.Sc., MFC

For site designers (e.g. engineers and landscape architects) to successfully design with trees in mind, a basic understanding of tree roots is a must. A common and persistent understanding of the root system is it roughly mirrors the canopy with thick, deep-spreading roots that look like branches. This perception is far from the truth, however; most trees’ root systems are in fact fairly extensive and relatively shallow.

There are three key components of the tree-rooting system. Structural roots are located near the base of the trunk, and their primary function is to help stabilize the tree. Long and rope-like transport roots emerge from the structural system and connect feeder roots to the tree’s vascular system. The fine or feeder root system is an extensive network of very small roots that collect air, water, and nutrients from the soil. These are usually found in the top 300 mm (12 in.) of soil, and are visible in the thick root masses that can be dug up with a hand shovel. Feeder roots can be found well beyond the edge of the tree canopy (i.e. drip line); in some cases, extending more than three times its diameter.

All three components of the tree root system are susceptible to considerable damage if any type of site disturbance is undertaken in close proximity to a tree. On newly developed sites, opportunities for root development—critical to long-term tree health—can be significantly reduced through poor site design or failing to plan to accommodate the needs of trees.

Read the full article: Designing with Trees in Mind: Incorporating trees into site development

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