Laguna Beach recently earned a Growth Award from the Arbor Day Foundation for the second year in a row! The Growth Award is a companion award to Tree City USA recognition, given to communities that demonstrate advanced levels of arboriculture and community engagement. Major milestones, innovative forestry practices, and public engagement combine to build progressive urban forestry programs that these awards recognize. This demonstrates that our community is committed to caring for our trees, and reinforces the long-standing reputation that Laguna Beach is a regional model for environmental stewardship. Congratulations, Laguna!

One such innovative forestry practice the Public Works Department recently implemented is called Root Collar Excavation. This was performed on one of our largest public trees after a seat wall and concrete pad around the base of the tree were removed (see photos on page two). This hardscape locked in moisture and compacted organic matter against the base of the tree; conditions that proliferate wood decaying fungal growth. The tree’s root flare is very susceptible to attack by these fungi. Decay in this area can spread to other parts of the tree quickly, and weaken the tree’s anchorage which elevates the potential risk of failure.

Root Collar Excavation involves forcibly removing the soil and organic material from around the base of the tree using controlled bursts of highly compressed air through a specialized tool called an Air Spade. Once the material has been moved away from this critical root area, arborists are able to inspect for any damage, and begin the process of remediation. Fortunately, there was no significant damage to this tree’s root flare, only a handful of large girdling roots (roots that grows in a circular pattern around the base of tree, gradually “strangling” it) that were removed before any irreparable damage was caused. Lastly, proactive root pruning was performed to encourage a more radial root structure to develop.

In general, it is always best to have the tree’s root flare even with the grade of its planting area. If it’s too deep, girdling roots or decay may affect the tree’s health. If it’s too shallow, the tree may not establish or anchor itself properly. Mulch around the tree is great, be mindful not to add excess material against the base of the tree, and avoid any hardscape barriers that trap this material against the trunk. It’s always best to consult with an ISA Certified Arborist by visiting www.TreesAreGood.org!

Matthew Barker — City Arborist