Tuesday, December 18, 2007

The Value of a Tree

I asked in the last article the question "How much is a tree really worth?"
A few weeks ago I found myself asking that very same question while working on a project just west of Yosemite, in Tuolomne county. I have been working as the ecological consultant and landscape designer on a 5 building college facility, nestled beneath a mature oak forest. We've been designing what we hope will be the coolest Child Care Facility ever, where kids will have a connection to nature and a desire to protect it and other natural places when they get older.
We're shooting for LEED certification on this, and the oaks are a key aspect of the 'greenness' of the project. In fact without them, our goal of eliminating the need for summer air-conditioning and reducing our cost to build and maintain the facilities would never be possible.
These are amazing trees, most sporting trunk diameters of three feet of more, and canopies that stretch out as far as 50 feet! Many of the trees are spaced so closely together that they have combined their shapes to form single arching canopies, their roots just as surely entwined with one another. With summer temperatures reaching sometimes in the hundreds for days at a time, these oaks will provide much needed shade for the buildings.
Building a structure in a mature forest is no easy task. It is well known that oaks trees suffer greatly form the impacts of development, from damage to their roots to alteration of the way water moved on the land they have grown up on. There are many different professionals who work as a team when planning any building project, and this one has the added responsibility of ensuring the health of these oaks. Normal projects involve altering the land dramatically, as when trenching to lay utilities, grading to make flat surfaces for foundations and handicap accessibility. Here we are not able to do any of that without first considering the effect on the oaks. Our buildings will be unique and attuned to their habitat, with special features such as piers over roots, which I like to think of as buildings on their tiptoes, that allow the buildings to rest on the land without altering it.
We are now in the process of awaiting permitting, and eventually the plans will go for public bid. It is an unfortunate fact that in the contracting world, the low bidders are the ones who get the contracts. This often means cutting corners wherever possible, including 'accidentally' losing trees to reduce the labor time needed to move materials and equipment carefully on a site. With all this special design put into preserving trees, the architect and I decided to write into the specifications penalties that would make construction think twice about causing our mascots any harm. I found I was crouched over my specifications asking myself, "How much are these trees worth if we had to replace one?"
I started reviewing the tree protection specification from other LEED buildings. Not much help there, this is a quiet revolution we're waging with this project. The numbers I came up with, when applied to my project, gave the average value of their cooling services at about $25,000 each, a negligible loss considering the value of the project itself. Then I factored in the service of providing the key element in the landscape and what that would take to replace. Then the value of keeping the campus lake free of soil runoff by stabilizing the hillsides. I got some figures on replacement of the trees, and was astounded to find the price of a mature oak at half the size would cost $36,000. This is just the price of tree and installation, without any of the administrative costs factored in.
In the end, the architects and I decided on a number that would make each tree worth around $100,000, though this value is by no means complete. I wince to think of any value attached to an organism that has taken so long to reach this size. I think of the Miwok Indians who must have planted these trees and then nursed them to maturity, knowing that future generations would be able to harvest the acorns, an essential part of their traditional diet.
Evaluating ecosystems services is a great technique to preserving functioning, intact ecosystems because it helps people realize their monetary value in this profit-driven economy. A growing body of economic and scientific evidence shows that humans simply cannot design systems that perform these core services better, be it filtering our air and water, providing the necessary pollination for more than 2/3 of our food supply, or even growing the natural products we get from the forests and oceans. This is another important tool in our arsenal when we as designers and scientists wage the quiet revolution.

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