Root Collar Excavation (RCE) is the process of excavating soil from around the trunk of a tree to inspect the root collar. This process is done to help expose the root flare, amend any compacted soil issues and inspect the root zone for overall root health and any potential girdling root concerns. Girdling roots are roots that grow around or across the tree trunk or other tree roots leading to restricted growth and eventual tree decline.
Tree roots need air to be healthy and vigorous. Compacted soils, mounded soil, and mulch over the over flare can significantly impact the ability for air to get to the roots and soil profile below. If your tree appears to have declined throughout the canopy when the leaves begin to form in the spring, a RCE would be recommended to identify any below-ground concerns. Unfortunately, in our urban environment trees are often planted too deep and/or the root flare wasn’t identified and exposed prior to the planting, these issues can lead to tree roots having the potential to encircle the trunk of the tree and leading to girdling issues. Many of our soil conditions in our urban environments are also contributing factors to tree and root health. Girdling roots will restrict the movement of water and nutrients to the leaves as they girdle the trunk. Though the tree will still grow, it will not be growing to its full potential and will be susceptible to future health issues.
Root Collar Excavation is used to thoroughly examine roots and determine the best plan of action to get your tree healthy and thriving once again. A tool that Kramer Tree utilizes to perform RCE is called an air spade. An air spade uses compressed air to safely, and effectively remove soil from around the base of the tree while reducing the risk of injuring large roots and the trunk of the tree. An air spade is also the recommended tool and treatment to rectify trees that have been what is commonly referred to as “volcano mulched”. This is an improper practice of over-mulching and mounding mulch and soil around the trunk of the tree. Volcano mulching is the ultimate result of numerous contributing factors, but essentially the soil around the trunk of the tree will choke the tree and root flare, creating an environment that encourages girdling roots and will stunt and ultimately be fatal for the tree.
Once these girdling roots have been exposed, an arborist can use a variety of tools to remove as many of these roots as needed. In addition to girdling roots, the arborist will then backfill the excavated area with a mix of the existing soil, fresh topsoil, and leaf mulch or other soil amendments. The leaf mulch or other additive will help improve the organic matter content of your soil profile which will help to reduce soil compaction issues. Less compacted soil will allow for improved and healthier root growth, increased microbial activity, improved fertility, and ultimately a healthier soil for your tree to grow in. Additional plant health care treatments such as fertilization or plant growth regulators may also be recommended, depending on your tree and soil conditions.
Our urban environment can be challenging for a tree to grow in. ISA Certified Arborists can help determine the best priority of treatments and actions to sustain and improve the health of your trees and soil. With routine care and maintenance of our trees and their growing conditions, we can maximize their growth and enjoy the many benefits that they provide us, our communities, and the environment.