I hope when I die I reincarnate into a willow tree. Maybe it's just me, but think about how cool it would be to be a tree. You stand there, looking gorgeous as fuck while soaking up the sun. Your pulp can be processed, and made into paper that can have an unlimited array of possibilities! You could be the piece of paper that holds Adele’s next-best single that's healing the heartbreak of lustful teens, your remnants could be the next book to surpass the global success of Harry Potter.
Trees are pretty bad ass, they’re a broad species of plants we give utmost respect too but often take for granted. Certain types of trees were prominent in many of the world’s mythologies and religions, believing they were given to us as an act of providence from higher, celestial powers. Research institutions have poured vast amounts of resources on research, focusing on the plethora of benefits trees give - from urban settings to the biosphere. These perennial plants provide ample amounts of wealth and resources to their surrounding environments and provide ecological stability on a global scale, but can we take these benefits to figure a dollar value?
To get a value out of a tree, we need to understand what all they do.
The first thing we learn in school that correlates with life science is the act of how plants use sunlight to synthesize foods from carbon dioxide and water. While that is undoubtedly the most important function of the plant kingdom, by providing oxygen, they also give an overabundance of other benefits. Trees can be hailed as multitasking prodigies, representing a system that does so much more than photosynthesis.
Canopies demonstrate an uncanny resemblance to physical filters, trapping dust and absorbing pollutants from the surrounding air - they act as a natural air filter. According to EnviroAtlas (EPA’s interactive web tool to discover, analyze and download data relating to ecosystem services) estimates that each tree at the age of 5 removes 3,700 pounds of air pollutants annually. Additionally, canopies provide shade from solar radiation and reduces noise levels, while tree tops act as reservoirs from stormwater by slowing the fall of rain, thus prevents flooding. Some species of trees and shrubs provide medicinal properties such as birch bark oil, a common antiseptic.
(1) Studies from respectable institutions have funded extensive research projects about the psychological benefits of trees. Scientific Reports published a journal entry in 2015 by a team of researchers from the United States, Canada, and Australia and was led by the University of Chicago professor, Marc Berman. This study compares two large datasets from the city of Toronto, Canada - the data was gathered on a block-by-block level. The first level of the study measures the distribution of green space, determined from satellite imagery while compiling a list of all 530,000 trees planted on public land. The second data set measured health that surveyed 94,000 civilians. After surveying income, education, and age, Berman and his colleagues showed that an additional ten trees on a given block resulted in a 1% increase in how healthy nearby residents felt.
Now we start getting into numbers.
When I was researching for this project I came across a pretty cool interactive web tool called i-Tree. It was developed by the USDA Forest Service to help determine the benefits and value of a tree canopy in U.S. dollars. However, i-Tree states:
“While some functional benefits of trees are well documented, others are difficult to quantify (e.g., human social and communal health). Trees' specific geography, climate, and interactions with humans and infrastructure are highly variable and make precise calculations that much more difficult. Given these complexities, the results presented here should be considered initial approximations to better understand the environmental and economic value associated with trees and their placement. “
The software analysis tool calculates the leaf surface area of a city, then determines the economic value of a specific species tree canopy. By using Google maps, the software can get a valid estimate of land cover types. “Governing” magazine of Portland, Oregon used i-Tree to bring the value of a canopy to the citizen’s attention, showing the tree-hugging city of Portland the value of trees in a perspective that everyone can perceive, currency. However, what's more impressive is that i-Tree did a study in Mesquite, Texas and found some key findings in its Urban Forest Analysis for the year of 2012.
(3) i-Tree determined that in 2012 there were 2,091,000 trees in Mesquite which created a quarter (24.4%) of the city in tree cover. Because of that cover, 288 tons/per year of pollution was removed ($1.54 million/year) while producing 31,900 tons of oxygen. Building energy savings estimated to be $773,000/year and annual rainfall interception was 30.2 million feet/year ($2.01 million/year). i-Tree estimates the total savings for Mesquite, Texas from trees in the year of 2012 was $4,314,000. Given the 1.28% inflation rate from 2012 to 2018, today that would equate to $4,657,344 (http://www.in2013dollars.com).
But what if I want to get the value of a tree I wanted to plant in my backyard? What would the annual dollar-value savings be? Lets just say I’ll plant the most common tree in California. (4) According to California Native Plant Society (which is where I’m from), the 5 most common trees in my region are:
Coast Live Oak (Quercus Agrifolia)
Fremont Cotton Wood
The Coast Live Oak is the most common tree in California. According to i-Tree if I were to plant a “Quercus Agrifolia” that was:
15 inches in diameter for the trunk size.
At least 5 years old
That was at least 10 feet away from my house
In full sun, year round.
My annual benefits for planting a Coast Live Oak would be $340.20/per year, if it was thriving. i-Tree, being the bad ass web tool that it is, broke down the numbers for me:
$11.36 in Storm Water savings, the act of controlling runoff at the source.
$25.36 in improving air quality by removing air-borne pollutants.
$83.33 in winter savings by strategically placing trees by allowing the sun to strike the southernmost part of my house, warming interior spaces.
$95.92 from recycling C02 back into breathable oxygen.
$124.32 by strategically placing trees, shading the east and west walls of my house, keeping it colder during the summer months.
Total Savings: $340.29/Per year
According to the EPA the median life age of an oak is 300 years, but lets scale it back down to a human’s lifespan. The World Health Organization estimates that the average life expectancy for 2017 is 79 years. So that means, over the course of 79 years, one Coast Live Oak is worth $26,882.91, respectively increasing as it ages. Numbers vary drastically depending on different species, how mature it is, if the tree is thriving, where it’s placed, if you count therapeutic benefits as a dollar amount, etc…
Due to the nature of complexity and extensive variation, gathering data to get the median annual value of a tree would just so much work. There’s a lot of variation from different species and their impacts on different environmental regions. With simple math, you could find the median - being if you had all the data compiled in front of you. You’d have to add up the sum of every tree’s total annual savings and divide by the number of species, all 60,065 of them.