Trees are the earth's endless effort
To speak to the listening heaven.
- Rabindranath Tagore
Just the other day, a friend issued a challenge, and I took him up on it.
As it turned out, we had both heard the same story on National Public Radio, which described how the trees of the planet had been counted.
According to the NPR story [ http://www.npr.org/templates/story/story.php?storyId=96758439 ] broadcast on November 12:
Ecology professor Nalini Nadkarni, from Evergreen State College in Washington, credits NASA satellite technology with making it possible to count the number of trees on the planet. Nadkarni’s research team arrived at a figure of 400,246,300,201 trees. Taking into account a global population of 6,456,789,877, that works out to 61 trees per person.
"Alright," my friend said, "human beings take in oxygen and give off carbon dioxide. Trees take in carbon dioxide and give off oxygen. Now that we know the number of trees per person, it raises the question of whether that’s enough."
"I see where you’re headed with this. In order to be sustainable, how many trees are required to offset the carbon dioxide of one person, right? And do we have enough?"
"Exactly. Can you come up with the answer?"
I’m glad he brought this up. I’ve been wanting to get started on a design project, and this challenge fits right in. Recognizing a need to downsize, I’ve been thinking about the next house I would build.
Actually, next time, I’d not start with the house and then add on the garden as an afterthought. Instead, I’d begin with the garden and then incorporate a house in the midst of it. The idea is not original to me. That’s how practitioners of permaculture approach the design of sustainable homesteads.
A well-designed home would be surrounded by concentric circles, or zones. Farthest away from the house is zone 5, a wilderness where you go to observe nature but do not intervene. Next in, zone 4 is a semi-wild place where you might forage for wild nuts and berries. Zone 3 is the orchard zone. Closer to the house, you’d arrive at zone 2, where you have the main garden plots for potatoes and similar crops that don’t demand daily tending or harvesting. Zone 1 would be the kitchen garden, a place to step out the door for fresh herbs and salad greens.
So, how many trees would you need on this permaculture homestead to offset the carbon dioxide of one person? Obviously, any answer I reach will be an oversimplification of some very complex processes, but I still figure it’s worth considering.
Back to the original question: how does the figure of 61 compare to the number of trees needed to offset the carbon dioxide that we exhale? (Admittedly, this fails to take into account our entire carbon footprint from powering our homes, transportation, food production, etc. But, for now, I'm sticking with the question as it was posed to me.)
After lengthy research that left me more confused than when I started, I discovered the following from the US Department of Energy, Carbon Dioxide Information Analysis Center (CDIAC) at Oak Ridge. It seems the matter of planting enough trees to offset our exhaled carbon dioxide is a moot point:
Should we be concerned with human breathing as a source of CO2?
A. No. While people do exhale carbon dioxide (the rate is approximately 1 kg per day, and it depends strongly on the person's activity level), this carbon dioxide includes carbon that was originally taken out of the carbon dioxide in the air by plants through photosynthesis - whether you eat the plants directly or animals that eat the plants. Thus, there is a closed loop, with no net addition to the atmosphere
[ Source - http://cdiac.ornl.gov/pns/faq.html ]
You’d think I’d be satisfied with that simple answer. But, of course, things start to get more complicated as you look at all the aspects of the carbon footprint. There’s much more to my carbon footprint than the amount of carbon dioxide that I exhale. It turns out that estimating the amount of carbon dioxide I am responsible for generating, comparing that to national and global per capita amounts, and calculating the number of trees required to offset my impact lead to a hopelessly confusing morass of contradictory and irreconcilable statistics. It’s an endeavor that raises issues for another story on another day.
Thankfully, there’s more to our relationship with trees than the carbon cycle. And nobody knows that better than the counter of trees, Nalini Nadkarni. Here’s the blurb for her recent book, Between Earth and Sky, Our Intimate Connections to Trees.
World-renowned canopy biologist Nalini Nadkarni has climbed trees on four continents with scientists, students, artists, clergymen, musicians, activists, loggers, legislators, and Inuits, gathering diverse perspectives. In Between Earth and Sky, a rich tapestry of personal stories, information, art, and photography, she becomes our captivating guide to the leafy wilderness above our heads. Through her luminous narrative, we embark on a multifaceted exploration of trees that illuminates the profound connections we have with them, the dazzling array of goods and services they provide, and the powerful lessons they hold for us. Nadkarni describes trees' intricate root systems, their highly evolved and still not completely understood canopies, their role in commerce and medicine, their existence in city centers and in extreme habitats of mountaintops and deserts, and their important place in folklore and the arts. She explains tree fundamentals and considers the symbolic role they have assumed in culture and religion. In a book that reawakens our sense of wonder at the fascinating world of trees, we ultimately find entry to the entire natural world and rediscover our own place in it.
In a recent interview, she describes the benefits of taking a more wholistic view of trees:
What I have learned from my outreach activities to diverse public audiences such as prisoners, poets, legislators, urban youth, Inuits, and modern dancers, is that I learn as much about trees and forests from them as I teach. They see the world – and trees – in different ways, with fresh perspectives, and that in turns wakes up my own eyes and brain from its entrenched past approaches. I believe that this is a theme that emerged in my book. I constantly described the different ways of seeing trees that I garnered from other audiences, with fresh metaphors and analogies. I have a proclivity to do that in everyday life, but by consciously opening the door and inviting in these new guests, I was able to see the forest and the trees in new ways, and to present those to my readers.
Finally, in this video, Nadkarni discusses the spiritual aspects of our relationship with trees.
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