I spend a lot of time reading scientific journal articles. Now, before you make your assumptions and claim that I’m a weird, unsocial hermit, remember that I’m also a student and working on my PhD in horticulture at CSU. Reading published work comes with the territory and it’s not as bad as you think—and it also keeps me up-to-date as an Extension agent. But there are many days that I feel like Elton John’s Rocket Man: “…And all this science I don’t understand; it’s just my job five days a week.”
There are many top-notch researchers
in horticulture…people I admire and secretly stalk in a non-creepy way…and I’m
always grateful to find articles that relate to my study. There’s something
really satisfying about tying together another’s research with my own and
helping me prove (or disprove) my research findings. But I can only think of a couple articles
that get me so excited that I bring them up to anyone who will listen…my dental
hygienist (“Moooah…muhha…trees.”), my mother (“Uh huh…that’s nice Al.”), my
beagles (who are excellent at looking the part with their heads cocked to one
side)…. One such article was just
published in September 2013:
|Not my beagle, but still cute!|
Ingram, D.L. and C.R. Hall. 2013. Carbon footprint and related production costs of system components of a field-grown Cercis canadensis L. ‘Forest Pansy’ using life cycle assessment. J. Environ. Hort. 31(3):169-176.
This study, in my eyes, is brilliant. Dewayne Ingram (University of Kentucky) and Charles Hall (Texas A&M) attempted to answer some simple questions: How much carbon does it “cost” to produce nursery trees? And does the carbon “cost” offset what the tree “absorbs” in carbon?
Carbon. Everyone talks about it and it’s currently popular to try to be “carbon neutral.” That means that the carbon (carbon dioxide and other greenhouse gases) it takes to produce a product will be equally offset by the amount of carbon the product stores. Many major companies and organizations have posted their carbon footprint for products or services. Timberland, maker of your hiking boots, has an average carbon cost of 40 pounds of CO2 per product. Compare that to Patagonia’s Talus jacket, which is 66 pounds of CO2. New Belgium Brewery, located in Fort Collins, has their beer production down to science: a 6-pack of Fat Tire comes in at 7 pounds of CO2.
|Photo from www.craftbrewingbusiness.com|
But it does take carbon to produce trees. Something I never really thought about. But yes, trees are produced using equipment, fertilizer, herbicides, etc.—which all release carbon dioxide into the atmosphere. But no one, until Ingram and Hall, had looked carefully at the carbon production costs of producing trees in the nursery. Their study can help nursery producers locate areas of production where they may be able to reduce carbon inputs. And this is what they found:
By using ‘Forest Pansy’ redbud as one example (they also studied maple and blue spruce), they found that the total carbon input to produce a redbud from seed to landscape “costs”
|Trees being loaded for transport at Van der Berk Nurseries|
But then these clever researchers took this study a step further…they estimated how much the tree would sequester in carbon during its lifetime. And this is where things get incredibly interesting. One thing to keep in mind is that the average life of a landscape tree is only 8 years. There are numerous reasons for this, but basically, the majority of our landscape trees don’t become the shade under which our children will lay.
|Photo from Mark Adams, Adams Arbor Care, LLC|
Let’s go back to that average life of a landscape tree. Again, most trees don’t live to be 40 years old. Based on information that Dr. Ingram shared with me, in order for the tree to be carbon neutral in its life (from seed to death), the tree has to live an estimated 22 years—almost 3 times as long as the current average.
So what does this mean? Well, several things. One is that we need to do a better job of producing, planting and maintaining trees to last longer in our landscapes. Another is that Ingram and Hall’s study can be crucial to a grower who is looking to not only save money on production costs, but to be more environmentally responsible. Part of the article focuses on reducing carbon inputs, like driving trees a shorter distance to a job site (driving 240 miles vs. 120 miles reduces carbon inputs by half, to ~4 pounds of CO2). Eliminating a year of production on the tree can reduce carbon by 2.6 pounds of CO2 per tree (from 4 years to 3 years). All important evidence a grower can use to make his/her businesses more economical and viable. Plus, let’s face it…don’t you think marketing a “sustainable” tree would be appealing to consumers?
I also think that this article is timely with the recent detection of emerald ash borer in Boulder. If we lose the majority of our urban ash forest due to this insect, a tremendous amount of carbon dioxide will be released in their removal, but also to replace them with other trees. And we lose the carbon absorption benefit from those dead, removed trees. That reinforces why it’s even more important to ensure that our newly planted trees survive, to help offset some of the potential new carbon emissions in our atmosphere. Whoa.