How much is my Green Ash worth?

By Marilyn Loser

Silly question? My trees are worth a lot to me.  Every day I look around my yard and am uplifted by the sight of trees. For me that’s enough. However, I received a phone call this week from a distraught LaJara lady whose trees had been cut down. The trees were of immense importance to her; their loss was devastating.  She felt her outrage fell on deaf ears, so she was looking for a way to calculate a tree’s monetary value.

I suggested she take a look at the free Tree Benefit Calculator (
It allows you to make a simple estimation of the benefits provided by an individual street tree (one planted in the front yard of a private residence). It is very user friendly. You click on your approximate location in the country, select the tree species from a list and enter the tree diameter 4.5 feet from the ground. The results will help you get an understanding of the environmental and economic value of trees on an annual basis.

One caveat before I proceed. The calculator is in beta version, which means its developers are still working on it.  It was created by Casey Trees and Davey Tree Expert Co.  They are very involved with the Forest Service in producing the iTrees database software, which helps cities to evaluate their community forests. Consider it a tool to use as a starting point for understanding a tree’s value rather than a scientific accounting with accurate values.

For example, my 6-inch green ash provides overall annual benefits of $119 according to the calculator.  Approximately $106 is its property value, $1 is the value of the estimated 152 pounds of carbon the tree sequesters, and the remainder is the estimated value of air quality, energy savings, and storm water benefits. Bear in mind, these benefits don’t take into account any tree maintenance costs. They also assume the tree is full and healthy.

My 12-inch cottonwood has an annual, overall benefit estimate of $203, with its property value contributing approximately $166. If I had a cottonwood tree with a diameter of 42-inches, its overall worth would decrease to $111 with a property value of $0 according to the calculator. 

That’s correct, a property value of nothing, nada. I couldn’t find anyone to question about this but I assume such a large cottonwood would be considered near the end of its life and in need of replacement.  On the other hand, this could be a glitch in the program. The calculator model uses a tree’s Leaf Surface Area (LSA) to determine increases in property values. It seems to me most large cottonwoods have a large LSA.

I don’t have any trees this large in my yard, but I feel, for my more moderately dimensioned trees, the calculator is a valuable tool. Remember, it provides a starting point.

With no property value, the 42-inch cottonwood’s estimated value would be based on anticipated energy saving ($37), ability to sequester carbon ($5), improve air quality ($11), intercept storm water run off and help prevent ground water pollution ($60).

Air quality is improved by the tree’s ability to absorb pollutants like ozone, nitrogen dioxide and sulfur dioxide through its leaves. Trees also intercept particulate matter such as dust, ash and smoke, and they and release oxygen through photosynthesis.

How significant is the 42-inch cottonwood’s ability to reduce atmospheric carbon by 642 pounds annually? Most car owners of a mid-sized sedan drive 12,000 miles and generate about 11,000 pounds of CO2 every year. The 6% offset due to this tree isn’t enough to combat climate change, but every well-cared for tree that is planted in a strategic site can reduce our individual carbon “footprint.”

Tom Wells, Colorado Tree Coalition President and resident of Broomfield, CO, provided this week’s quote. He said, “We encourage everyone in Broomfield to use this tag or something similar on their emails to help reduce the amount for copies/paper being used in the City.”

“Please consider the environment before printing this email.” Tom Wells