We all know that trees are good, right? They provide shade to cool us off, habitat for birds, animals and insects, increase property values, create the oxygen we breathe and sequester the carbon dioxide we produce. Hopefully, we all have positive memories from childhood of climbing our neighborhood trees, making us feel like we could conquer the world! I know I do, and now I encourage my own kids to learn how to climb them, and take care of our trees, and yes, even their botanic names…I am a Landscape Architect, I can’t help myself! But do we really know how important trees are and why we, you and me, need to plant more trees?
North Carolina State University has determined that a mature tree can absorb 48 pounds of carbon dioxide each year, and over the first 40 years of a tree’s lifespan, it can sequester one TON of carbon dioxide! Amazing! The reality of Chicago’s urban forest, which is estimated at 3.5 million trees and covers more than 17% of the area, removes over 25,000 tons of carbon each and every year. Good for us, bad for carbon dioxide!
We also know that an average sized healthy tree can produce 260 pounds of oxygen annually, but that the average person uses over 380 pounds or oxygen each year. So we each need two trees to support our oxygen needs. With over 7.315 BILLION people on this earth that’s almost 15 billion trees we need to support the current population. Lucky for us, NASA and USGS estimate the number of trees on the planet ranges between 400 billion to over a trillion. It’s not an exact science, even with the Landstat imagery they’ve been collecting since 1972.
Trees also trap more of the sun’s energy than any other organism on earth. Of the 0.1% of the sun’s energy that is captured, trees account for 50% of that energy! Way to go trees, great job!
The USDA Forest Service states that properly placed trees around buildings can reduce air conditioning needs by 30% and can save 20-50% in energy used for heating. They also determined that the cooling effect of one healthy tree is equal to 10 room-sized AC units operating 20 hours each day! Bottom line, trees help save money with cooling and heating our homes and buildings.
The lifespan of a tree in the forest or non-urban area ranges from 50-300 years and averages 100-150 years, but in urban conditions this is dramatically shortened to an average of just 13 years. So when you decide to plant trees, determining where to plant them is just as important. Make sure there is fertile, uncompacted soil, with lots of room for roots to spread out. Think about how big that tree’s canopy is going to be, and plant trees far enough apart from each other so they can reach their mature size. When planting trees in urban areas like
streetscapes and parkways, make the planting areas as large as possible, plant the tree’s root ball high so the root flare is exposed, skip the tree grates and don’t forget to plan ahead and budget for their replacement. Early in my career, I was once told to plant a 50-cent tree in a $50 hole. It still remains great advice for planting healthy trees today. If you’re going to plant a tree, invest in the soil and space that will support that tree for as long as possible. That way you can continue to enjoy their full benefit for many years to come.
In my 20-year career as a Landscape Architect, I’ve averaged 375 trees per year, more than 13,000 trees, that I’ve had influence on planting. Over that time period those trees have absorbed over 7.16 million pounds of carbon dioxide and produced 38.78 million pounds of oxygen, which is enough oxygen to support 100,485 people for one year. Those 13,000 trees each year will continue to absorb 630,500 pounds of carbon dioxide and produce 3.4 million pounds of oxygen, providing 8,848 people with one year of oxygen. Still think you can’t make a difference? You can if you just plant trees!
Data sources and additional information: