Down to the Roots: Tree Protection During Construction

Digging trenches with heavy machinery can impact the health of campus landscapes and trees if not managed carefully. Big Shift construction crews take multiple tree protection and conservation measures to limit these threats.

“Starting with the design process, to moment-to-moment decisions on the ground, the protection of trees is always an important factor in any of our construction plans,” Christina Reyes, campus landscape architect, said.

Before breaking ground on the trenches needed for this project, the Big Shift team consults John Lichter, an arborist from Tree Associates, who serves in an advisory role throughout the design process. However, careful pre-planning is only a small piece of the puzzle.

“No two trees are the same,” Reyes said,  "it’s impossible to know what’s going on underground just by looking at the surface.”

Root damage mitigation

To mitigate root damage — the most direct way construction can impact a tree — the arborist oversees an exploratory hydro excavation in areas where trenching could impact nearby root systems. This practice allows the team to view the root system and assess potential issues. Then Lichter can make recommendations, such as what roots are critical to preserve, the best way to cut roots when necessary and procedures to take if a root is accidentally damaged.

“When digging near a tree, certain impacts are unavoidable, but there are protective measures and best management practices we implement to minimize damage,” Reyes said.

For instance, exposed roots are wrapped in burlap and kept moist to avoid sunburn and dehydration. Roots that cannot be preserved are cut clean before the trenching work begins to facilitate healing and re-sprouting, otherwise they are more susceptible to decay and less likely to heal.

Protection against soil compaction

While root conservation is an important aspect of tree protection, it’s not the only one. The weight of large construction machinery can lead to soil compaction.

“Trees take in oxygen and water from the soil through their roots. The more compacted the soil is, the more difficult it is for oxygen and water to move through it which has significant negative implications for the long term health of the trees,” Reyes said.

In areas that may be sensitive to compaction, construction equipment is placed on layers of plywood and bark mulch. Mulch cushions the weight, while the plywood distributes the weight over a larger surface area. Tree protection fencing is also installed to minimize the impact area around trees. Having these procedures in place helps reduce damage and so is the ability to be flexible.

“There are a lot of moving parts and restricting factors when digging trenches. Adjustments often have to be made in the field.” Reyes said. “The arborist’s job is to use their expertise to ensure risks to trees are understood and always remain an important part of the conversation."