TREES AS CLIMATE MODULATORS.

Our Magnificent Trees.

Fall is coming to its wintry end here in the northeast.  The leaves have fallen and accumulate in crunchy red-brown piles and wind rows. The bare trees stand out against the sky in their complex and puzzling tracery. Now rather than seeing a forest in its varying hues of green, one can actually see the individual  trees which make it up.  Our native forests once covered near all the land,  in many places they still persist as diverse woodlands comprised  of species of oak, hickories, tupelo, black walnut, beech, sassafras, maple, birch, pines, and so many more. Now that winter approaches they can be appreciated as individuals. 

Our national US Forest Service reminds us that trees and forests are what make this earth habitable. By the process of photosynthesis each mature tree can remove from the atmosphere more than 48 pounds (22 kg) of carbon dioxide from the air each year (USFS).  This wondrous chemical process occurs in the green leaves where, powered by sunlight, CO2 gas from the air combines with water from the soil to produce carbohydrates, such as simple sugars.  And thankfully, for us air breathers, as a result of this chemical reaction, trees give off oxygen as a waste product. The amount of O2 released by a mature tree is claimed (USFS) to be enough oxygen to sustain four individuals  for a day (or one of us for four days).  

But oxygen is not the tree’s sole benefit to us humans.  The simple sugars they produce by photosynthesis  are polymerized by specialized cells to produce complex sugars, starches, and most importantly, insoluble, tough, cellulose. 

Cellulose is used as a support tissue to maintain a tree’s structure and to insure access to sunlight and, as well, to enable the tree to transport water up to its leaves and to store sugars produced in the leaves.  Cellulose makes up the wood (it’s transport and structural tissue) , as well as bark, leaves and roots. 

It is by this process —cellulose production—that a tree can store so much of the carbon it removes from the air.  The carbon atoms are tucked  away in the C-H-O polymer molecules of cellulose, the tissue that serves for support and for food and water transport.  Aside from the water and other fluids in a tree,  cellulose  comprises most of a tree’s mass.  The roots 

comprise about 20% of the tree’s biomass, it’s trunk (60%), branches and stems (15%)  and leaves (5%) of the tree. 

Each year, most broad-leaved trees in the temperate forests lose their leaves—but this amount is a small portion  (5%) of the tree’s biomass.  The leaves fall to earth where they slowly decay into humus as they oxidize and give up the CO2 that was stored in the cellulose and form valuable humus which is incorporated into the soil. 

But 95% of the tree holds on to its carbon-storing cellulose in its growin groots, its expanding trunk, and burgeoning and over arching branches and stems.  

Since many trees live  hundreds of years—some even into the thousands—this storage of carbon as solid  cellulose tissue is one  important means by which CO2 in the atmosphere is controlled. Our earth’s innards are geologically and chemically active and tend to spew  out lava (and CO2 gas) regularly at vents and volcanoes.  

It has  been the earth’s forests which for hundreds of millions of years have, among other natural systems, helped to remove and control the build up of this earth warming gas—CO2–and sequester it—-as cellulose -as tree biomass.

A mature oak tree will remove more than 48 pounds of carbon from the air each year as it converts CO2 gas into cellulose tissues which make up the bulk of the solid tree.  That ancient white oak tree in my back yard which is two hundred years old, has removed and stored 480 lbs of carbon every decade, and 4,800 lbs in a century, and almost 10,000 lbs of carbon over its life time-so far.

That is why trees and forests are so important!!!!  Imagine the view from a Vermont or Colorado mountain top over rolling hills carpeted with trees. Each tree in the millions pulling 40/50 pounds of CO2 out of the air each year.  That is how we must envision our forests. 

When that tree dies its carbon will slowly reenter the atmosphere again, But that decay process may take another hundred years to complete.  But here we are speaking of forests made up of many many millions of trees. As one tree dies and gives up its carbon another young tree is taking it in and using it—removing it from the air.  

So this is why our trees and forests  are so import to us. They provide us with both oxygen to breath, and as well, act as modulators of our earths temperature.  

As forests grow and expand they (absorb earth warming carbon) cool the earth’s atmosphere.  And when they shrink and decline, they release stored  carbon and cause the earth to heat up.  They are living thermostats that can remove and sequester from massive amounts of earth warming  carbon dioxide over very long stretches of time.  

Over the millennia humans have cut and burned down our magnificent forests. To add insult to injury they also dug up buried (fossil) carbon (coal and oil) and burned these substances in the sir for fuel in the process generating  CO2 which had been long buried.    Both of these processes destroying forests and adding fossil carbon to the air cause the atmosphere to warm up.  

Evidence from our geologic past support the contention that forests are the best possible way to overcome excessive earth warming.  

It is an established fact that were we able to reforest all those areas on the earth that we have desolated and stripped of forests, we could bring the excess atmospheric fossil carbon dioxide  under control.  

For success,  such a process would also have to be combined with other difficult decisions about how we use and abuse fossil fuels, and how to control and maintain the human population on the earth at sustainable levels.  Seven billion souls and going up is a sure path to catastrophe. 

Please don’t cut down that tree. Please plant another in the  place of one which has died or been cut. But individual  trees are only a part of a living forest.  It is our forests which make the earth truly habitable and help keep it cool.