Healthy Trees Start Below Ground

Updated: Apr 20

Written by: August Hoppe, Certified Arborist WI-477A

The below-ground roots of trees are critical to the success of all trees. Unfortunately, since roots are not viewable from above the ground, their importance to the health of a tree is often ignored. Roots provided numerous important functions for trees. Anchorage and stability in the soil, energy (in the form of sugars) storage, and water and nutrient uptake. A strong root system will help the tree flourish and create a vibrant canopy of leaves above ground.

Tree roots
Even with mature trees, most of the roots are within the first couple feet of the soil horizon. Most of the available water, nutrients and organic matter are contained within these first couple feet. Ensuring that the root zone in this soil area is healthy is crucial to a happy and healthy tree.

Soil Volume

Soil volume is one of the most important contributors to root and overall tree health. Simply put, the more soil available to a tree the greater the potential is for a long-lasting tree. The average life span of a forest-grown tree can be 100+ years, while a tree on an urban street setting with limited root area may only be 15 years. Roots need space to grow and develop and seek out water and nutrient resources.

Organic Matter

Organic matter is a critical part of a healthy root system as well. Organic matter helps retain moisture and is packed with the nutrients that roots need. Organic matter lies on top of the soil profile. The top layers of the soil (including the organic matter) have more water and nutrients than lower subsoil sections of soil. In our urban areas we often see disruption of the organic matter in the soil profile. Digging, leveling and filling of soil for construction projects can alter the layers of the soil profile and can mix the less nutrient-rich subsoils into higher areas of the soil profile, making it harder for roots to find the resources they need.


Porosity is another key indicator of soil health. This is the space between soil particles. More space means more available capacity for both oxygen and water - both critical to healthy roots. Compaction of the soil around a root system can cause major issues for trees. Compaction crushes the soil particles into tighter arrangements and reduces the porosity, which in turns means that the soil is not able to hold as much oxygen or water. Compaction is often caused by heavy equipment or vehicles driving over the root systems. Protecting root systems and avoiding compaction during a construction project can make a big difference in the life of your tree.

Trees living in our urban areas face numerous challenges with soil volume, organic matter, and soil porosity. Arborists have many tools to help correct soil issues for trees. Soil injection fertilization treatments can help provide additional nutrients and open up porosity in the soil profile. Growth regulators applied around the base of a tree can help stimulate fine absorbing roots to aid in uptake of water and nutrients. Root aeration can help till the soil and reduce the effects of compaction.

As our summer transitions into the fall season, trees will be starting to move their energy resources away from their leaves back into the root systems for winter storage. Since the root systems are still very active in the fall, it is a great time to perform treatments to improve health.

So even though roots are hidden away under the ground, it’s important to remember how important they are. Contact Hoppe Tree Service to have a check up of your trees, including the roots!

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