The Art of Tree Management

“We managed light, we paint with light, and we paint with shade in our trees.”

A couple walks through the light and shadows created by an urban forest. Photo credit to Natalie Cheel

This is how Dr. Kim Coder begins his recent discussion of tree management on Arbor Views, the podcast for the International Society of Arboriculture.

What a unique way to describe how arborists integrate trees into our environment! They work with the absence and presence of light yet, their art sets its course in a potential stage, and arborists must continue to negotiate with the trees themselves in order to manipulate their benefits and obstacles.

“All the benefits we derive from trees, many of those things actually are a proxy for how healthy the crown is, how healthy the green stuff is. We can make bigger stronger trees …which is what arbor care is all about”

Several simple models help us develop each tree’s potential growth. This gives us better clues to evaluate how our own trees are doing. In fact, 78-82% of the weight mass of a tree is from water:

“If you look at a tree, if we had infrared vision, we could see that in a nice sunny day, it’s a fountain of water … below the leaves, coming from that crown is just a bubbling cauldron of water vapor.”

That description illustrates how Dr. Coder found that about 80% of all variation in tree development is due to water – whether there’s too much or too little or how the aeration process for the water vapor is managed.

This type of research demonstrates the greatest tool we have to manipulate the soil or the branches, and guide the tree as our paintbrush. But also, this research teaches us that more patience is necessary for letting the tree figure out its issues.

Who knew tree scientists are artists painting the canvas of our cities with light!

The Trouble with Storms

There are a ton of benefits that trees provide for our cities, neighborhoods, and homes that we can take for granted. Last week we mentioned that a large percentage of the monetary value provided by trees is by mitigating stormwater.

In the Gulf coast, the damage from both the drought and flooding are disrupting city and rural life as Ivan (now a Tropical Storm) passes. Although here in Washington State we don’t encounter hurricanes, all urban folk rely on cities to take care of water flowing through our soil and over our roads. Cities provided the infrastructure to collect, distribute, and treat stormwater and sewage at once, meaning that the pipes and tunnels can get overwhelmed when storms occur.

Here in King County, the Wastewater Treatment Division (WTD) is concerned about overflows that can occur when the system’s capacity is overwhelmed by stormwater. This causes environmental and health problems when overflows contain more than just stormwater, but also some sewage. The WTD’s project for Bioretention is one way the county takes advantage of the natural absorptive power of vegetation.

From the Arbor Day Foundation’s publication “Tree City USA” Bulletin 55

Trees are great at managing stormwater runoff from the leaves disrupting rainfall, to the roots system’s

storage of rainwater. According  to the Alliance for Community Trees, mature trees can hold 50 to 100 gallons of water during large storms. Strategic tree planting can relieve pressure off of more traditional infrastructure – Detroit reduced overflow in 2010 by 10-20% in volume, saving about 159 million dollars a year. Trees are an effective, environmentally-friendly solution to an expensive problem.