The Truth about Trees

 I am sitting through another meeting where someone is saying that it is ok about the trees being cut down because there will be replacement trees planted.  I sigh.  I have come to learn that our public education system teaches people nothing about trees, and thus most people know nothing about them.   Most of us cannot identify anything but the most basic trees a Maple, an oak or an "evergreen" (which is really many many trees which we are lumping into one category.)   We view trees as pretty, and practical - meaning they are good for building stuff and making paper.  But because they can "grow again" we think nothing of cutting them down.

Here is a list of some of the things I wish people understood about trees:

Trees Improve Air Quality by removing pollutants

Lower Asthma Rates

Studies show lower rates of Asthma in neighborhoods with greater tree density.  Low income neighborhoods tend to have fewer trees making this an equity issue.

Prevent Heat Islands

Cities can be 12F higher than other areas because of density.  Under climate change this can be fatal.

Lower Heating and Air Conditioning Bills

Trees provide cooling benefits in the summer and wind-chill reduction in the winter resulting in energy savings in nearby buildings. Olympias street trees in 2019 alone provided energy savings of 785,00 about $330 per building.

Storm Water Retention

Trees reduce and slow stormwater by intercepting rain in their leave and branches.  It is soaked up by tree roots rather than runoff from streets and sidewalks.   This can help prevent flooding, stream bank erosion, habitat destruction, sewer system overflows and contaminated water bodies.  The technological ways of managing storm water are expensive!

Drought Prevention

By roots drawing water into the ground they help lessen the impacts of drought.  This will increasingly matter with climate change.

Wildlife and Insect Habitat

Trees provide critical habitat for birds, mammals and insects.  Part of the loss of bird diversity is attributed to loss of habitat.

Mental Health benefits from proximity to trees

Studies show lower levels of depression if people can even see a tree out their window.

Aesthetics/ increase property values

We of course find trees beautiful but that beauty also translates into higher property values.

 Carbon sinks

Trees absorb carbon dioxide from the atmosphere.  The carbon is stored in its roots and in the soil, thus reducing carbon emissions in the air (carbon sequestration.) Carbon sequestered in this way helps to maintain and regenerate the surrounding community of trees and other plants. As long as the tree is allowed to live, it continues to store carbon and keep it out of the atmosphere.  When it is cut, according to the Sierra Club, 60% of the stored carbon is immediately released to the atmosphere – the rest depends upon how the tree is used.

Trees take in Co2, a greenhouse gas, and, in exchange, they transpire oxygen which we breathe.  Street trees in Olympia collectively sequester more than 420,000 pounds of carbon every year (~2 metric tons).  Each street tree on average has stored over 2,000 pounds of carbon over its lifetime and continues to store carbon as it grows.  Street trees in Olympia have stored more than 5 million pounds of carbon!

Zarghami, H. An Ecosystem Assessment of Olympia’s Street Trees. Evergreen State College. 2020.

Thus when we talk about cutting down trees we must understand we lose their stored carbon and we lose their annual drawdown capacity and we lose all their future annual drawdown which would occurred till the end of the trees natural life which for many species is longer than a human life.

The IPCC’s most recent report has said that we can no longer globally avert disaster by reducing emissions alone.  It has stated that we must aggressively plant trees world wide in order to increase our capacity to sequester GHG’s.   

All trees are not equal (and this is why I wince in those meetings where they talk about cutting down a great big tree and replacing it with a sapling)

A 30” tree provides 70% more “environmental services” than a 3” tree.

The following table shows Carbon Sink or Sequestration per EPA data:

From the EPA	Hardwoods	conifers
1 year old tree	1.6 to 4 lbs carbon/per tree/annually	.9 to 2.2 lbs carbon/per tree/annually
35 year old tree	20 to 79.3 lbs carbon/tree/annually	15 to 65 lbs carbon/per tree/annually

 

This is critical to understand since typically developers give lip service to the cutting of trees by saying they will plant replacement trees.  Even when they plant the same number (which is rare) they are not replacing the level of environmental services those trees were providing.  To cut down even one 30” tree would require replanting with 70 3” trees to drawdown the same amount in the next year.  That is why they are called Exceptional trees.  They are irreplaceable.  It takes about a 100 years (depending upon species to achieve that same level.

One of my friends wanted her neighbor to cut down a 100 year old tree in their yard to improve her view.  I said: "Respect your elders...that tree has lived way longer than you".   She thought I was making a joke.  I was not.  The tree has been witness to a 100 years of human goings on, it holds wisdom.  Almost all trees are part of a community - connected underground to other trees.

When you understand the list above of all the things trees do for us, you realize that we are part of an ecosystem in which they are supporting us.  It is about time we returned the favor and protected them.