TreEconomics –Who Says Money Doesn’t Grow On Trees?

Technically, no, twenty-dollar bills don’t spring forth from leaf buds, nor do Benjamins drop lazily from the canopy in the fall.  You can’t crack open a walnut and find a silver dollar.  But, in today’s economic climate you should reconsider what your mother used to say, because although living trees don’t provide us with money, they can definitely keep us from spending it.

When one applies science and economics to study the value of a tree, one will ultimately discover that the tree is incredibly invaluable.  What I mean to say is that the ecosystem services, the goods provided to us by trees, are numerous and diverse, and positively affect our lives daily whether we understand it or not.  I think it’s safe to assume that most people recognize that through photosynthesis our simple, oxygen-dependent cardiovascular system is supported by trees.  And from my childhood experiences in Atlanta,GA, most people welcome the shade of a tall white oak in the dog days of summer.  But what else are we missing, what other critical roles do trees play in our ecosystem that we don’t take time to understand?

  • Trees are filters – they absorb and retain water that flows over land through the process of infiltration.  During infiltration, a significant amount of heavy metals and other pollutants carried in the water are removed by the tree, the end result being cleaner water stored in our aquifers, and less cost to remove those contaminants before human consumption.
  • Trees are like linebackers – in winter, evergreen species block cold winds from penetrating your house, therefore reducing draftiness and the subsequent need for conditioned air…equaling a lower heating bill.  In the summer, their deciduous counterparts reflect and absorb the sun’s rays, leading to a temperature-normalizing effect and a reduction in cooling costs.
  • Trees are grounded in reality– their root systems hold our soils in place, preventing erosion and unnecessary sediment loading into our waterways during heavy rain events.
  • Trees are strongholds – through photosynthesis, elemental carbon is separated out of carbon dioxide and stored in the tissues of living trees.  We know that atmospheric carbon exacerbates the trapping of heat within our atmosphere, and so without its sustained removal and storage our planet would suffer from wild fluctuations in climate driven by unregulated temperatures.

So what does all of this translate to?  In an urban setting, trees lower costs, increase savings, provide cleaner water, cleaner air, even marketable products (in the form of carbon credits).  There are now ways to quantify with one-cent accuracy the amount of money trees save us, especially in our cities and hardscapes where impervious surfaces, automobiles, heavy metals, and extreme temperature fluctuations are abundant.  Even street trees, root-bound by concrete on all sides, provide simple and beneficial ecosystem services which should not be overlooked.  For example, the city of Corvallis, OR (roughly 53,000 residents) used a computer program to value their urban forest’s annual worth at close to four million dollars; that estimate was generated by data collection in forested areas, street trees, shrubs, and grasslands, and included in the savings were pollutant removal, carbon storage, stormwater reduction, energy savings, and increases in real estate values (EPA).  Based on that figure, it certainly seems like more cities would pursue initiatives to protect their urban forests, if only for the economic savings generated by their presence.

Maybe we should change the age-old phrase to say “money doesn’t grow on trees, it grows through them”, all the way from the stabilizing roots to the shading canopies.  That might change the way we look at them.  The investment in and preservation of urban forests generates real and quantifiable annual returns which are in no way insignificant.  Add those tangible benefits to the incalculable aesthetic value of a tree, of a whole forest of trees, and we may just be able to strike a balance between science and economics and begin to grasp the incredible worth of a resource we so easily take for granted.

Owen Carson, Field Technician (and tree-hugger)

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