By the Mount Rainier Tree Commission
One of the most beneficial shade trees in Mount Rainier to humans and wildlife is the oak.
According to experts, oak trees support more diversity than any other tree, providing food and habitat, as well as countless insects that serve as the food base for many species, such as year-round birds like cardinals and migratory birds like warblers.
Oaks also provide abundant shade and mitigate stormwater runoff, which will be increasingly important in a wetter and hotter future. Caring for and planting an oak tree might be the most forward-looking act any of us can take.
Although many large oak trees in Mount Rainier are still standing, especially between 31st and 32nd Streets, several have come down in the past few years, and several others are in decline.
In 2019 and 2020, neighboring municipalities and tree-related experts noted an unusual number of oaks dying, especially large white oaks, resulting in a flurry of activity to determine the cause.
Fungus and boring insects such as the ambrosia beetle were killing mature white oaks because they became stressed by water-logged soils due to record rainfall, followed by extreme heat and drought the following year.
Sadly, ambrosia beetles were the cause of several trees in the neighborhood being lost - with many dying in a matter of months. Beetles bore into weakened trees and spread a fungus that interrupts the tree’s ability to transfer nutrients.
Insects like ambrosia that are getting a foothold in our region may seem like an insurmountable challenge but there are things to help prevent stress on large trees to keep disease at bay:
1. Minimize root damage to root systems of large trees such as construction activity and parking cars near the root systems.
2. Add mulch (2-3” max) in a 6’ to 10’ radius around the trunk of a large tree. Be sure to keep the mulch away from the trunk itself (avoid mulch volcanoes). Adding mulch around your tree provides vital nutrients.
3. Have a licensed arborist evaluate your trees every couple of years if you are able. It is hard to stop ambrosia beetles from invading a sick tree but regular monitoring can be effective. You can monitor your tree for signs of the beetle, as well as entry holes on the trunk and sawdust “toothpicks” that protrude from the hole being bored. If you see signs of beetle activity, contact an arborist without delay. There are some chemicals that may be effective but must be applied by professionals.
Climate change is a daunting existential challenge, but trees can help and it starts with taking care of the big trees we already have in our community, as well as planting more for the future.
If you are interested in planting a canopy tree on your property but aren’t sure where to start, the Tree Commission can help. Contact trees@20712.org.
The Tree Commission's next meeting is coming up on August 2. Visit the City's Calendar to view upcoming City meetings and events: https://www.mountrainiermd.org/calendar