What do you think of when you hear the words tree protection or tree preservation? I start by thinking about what makes common sense and then I start to think like an arborist.
Over the years of inspecting trees I’ve noticed a few definitions of tree preservation people might use:
If the tree is still standing and still alive when the sod is put down, then the tree was preserved!
This was from a driveway contractor: “I’ve never killed a tree in my 20-plus years of installing driveways next to trees.” I do not think this is true.
“If we put down a plastic fence, spray the tree for insects, and fertilize the tree then the tree is preserved.”
Another preservation method might be having zero impact around the trees drip line, no trenching near the tree, no compaction near the tree and little impact on drainage flow patterns (while common sense would say this would be good protection, this is rarely the case and rarely an option)
There are a lot of variables to consider while planning and designing a project with the trees in mind. After consulting with some of our clients over the years, many have held off on a house addition to avoid damaging or worse, removing, their tree.
Here are some things to consider when attempting to preserve your trees:
Condition of the tree: Do we want to preserve a tree that is in decline or in poor condition?
Species: The tree might be a short lived species at the end of it’s time or it could be a tree that is very sensitive to any disturbance.
Size of tree: Sometimes the smaller and medium trees make more sense to preserve rather than a single large tree. Larger trees also need larger protection zones.
Groups of trees share a mycelium connection, which helps with preservation instead of just a single tree.
Look at soil type. Wet and clay-rich soils have more issues with compaction
I like to think of tree protection as soil protection. Here is a list of things that can be done before and after construction damage to reduce stress on a tree and the soil around it:
If vehicles need to drive across the root zone of a tree, install a road of deep mulch, install mats or plywood or sometimes I have seen landscape fabric and stone which is to be removed after the project is completed. If you are really curious about this, there are specs and standards.
If an irrigation head needs to be installed near a tree, make sure the water line does not run perpendicular to the root of the tree and cuts all the roots but comes in towards the tree straight and parallel to the roots, like the spoke of a wheel.
If at all possible, do not change the grade of soil around the trees you would like to protect. Grade changes are common on many if not most construction projects. Either soil is removed or soil is added, and most of the time the soil removed is added to other parts of the yard.
Do not have bare soil ever. Bare soil during construction (and, actually, anytime) is not good for the microbes that live in the soil. A layer of mulch, plants, cover crop, rye grass or anything similar is better than bare soil.
Create a physical barrier around the tree/trees you would like to protect. Wooden or chain link fences around trees to be preserved work better than plastic fences that can be moved more easily.
Pruning trees before construction can reduce the amount of damage from building materials, trucks and loaders hitting limbs.
When in doubt, talk to an arborist. There are techniques that can be implemented to reduce stress on the tree for future construction work to be done.