Protect Against Physical Damage
A healthy tree is generally hardy and resilent. Yet even the healthiest tree can be damagaged or killed by common practices. Here are a few steps you can take to keep your tree healthy and safe.
- Don't top: Removing the top of tree (topping) is never recommended. While this may seem to be a good way to reduce the height of your tree, the tree's reaction to such treatment will be to send out multiple shoots from the point at which it was cut. These shoots will quickly grow taller than the original tree and because they are weakly attached they are prone to breaking. The end result is a tree that is taller, less sightly, and less safe than the original tree.
Anything wrapped around a tree's trunk too long can cut off the tree's supply of essential water and nutrients.
- Avoid strangling: Anything wrapped around the trunk of the tree can strangle (or girdle) and kill the tree by preventing the uptake of water and nutrients. Common culprits include wire, bike locks, hoses, and plastic ties - but anything wrapped around the tree can cause a problem.
- Remove stakes: Young trees should only be staked if the tree cannot stand up straight on its own. Stakes should be removed 1-2 years after the tree is planted. Stakes should always be placed about 1 ft away from the tree and attached to the trunk with a soft rubber tie. Never leave a stake tied directly to the trunk. Tree trunks are like human muscles and need to flex in the wind in order to build strength. Anything that prevents the trunk from moving will prevent the trunk from growing stronger. Stakes left in too long can also cause wounds on the trunk and any branches they touch.
A tree killed by repeated hits from a weed wacker.
- Do not nail: Nailing signs or anything else to a tree leaves wounds that open the tree up to infection by pests and disease.
- Keep weed wackers / string trimmers / lawn mowers away: Repeated small nicks to the base of a tree from a weed wacker add up over time to cause severe damage and death to trees. This is a very common problem. The best way to avoid such damage is to not allow grass to grow within 1-2 feet of the trunk. Suppress grass growth with a 2-4" thick layer of bark mulch. This mulch will provide the added benefits of supplying nutrients to the tree and maintaining critical soil moisture.
Piling construction materials around the base of a tree can cause serious injury and death.
Protect During Construction
Proper tree protection during construction is critical to maintaining tree health. Soil compaction from heavy equipment and trenching results in root damage which maydestabilize or eventually kill a tree. Root damage can also come from roots that are cut to make way for new structures. Trunk and limb damage exposes a tree to disease and structural failure. Regrading the surrounding landscape, trenching near the tree, or installing impervious surfaces over a tree's roots can also severly damage a tree.A tree damaged from construction may slowly die over a period of several years.
Protect your tree during construction by establishing a zone of protection around the tree early in the process. Within this zone, no trucks should be allowed to drive, materials to be stacked, or soil to be piled up. This area should be as far out from the tree as possible, but at least 1 ft radius from the tree's trunk for every inch of trunk diameter. Mark off the area with clearly visible fencing. This fencing should remain in place for the duration of the construction project.
The best way to ensure the proper protection of a tree is to involve a certified arborist experienced in tree protection during construction from the start of the construction planning process. Protection of street trees during construction should be coordinated through the Department of Transportation's Urban Forestry Division.
Why topping hurts trees
Avoiding tree damage during construction
Treatment of trees damaged by construction
City of Seattle standard plans for tree protection during construction (scroll to plans132a, 132b, and 133)
Plant Amnesty's referral service for Certified Arborists