Bulletin

“Although I haven’t been to Bullard Woods in a number of years, I know the site well and have measured many trees there over the years for the Native Tree Society (NTS).

My particular skills are in old-growth forest ecosystems interpretation and measuring trees at the individual and stand level for a variety of purposes. Unexpectedly, my tree-measuring skills have found a new relevancy in recent years. Please, let me explain. One of the environmental benefits of a place like Bullard Woods is its timely role in storing larger reserves of forest carbon. . .

One point that immediately comes to mind is recognizing the importance of the really large trees in holding sizable amounts of carbon. It is a topic of considerable discussion among climate scientists these days. Younger forests are often given too much credit because of their high growth rates. Unquestionably, they are important, but it is the older forests with an abundance of large trees that are holding the big carbon reserves, which need to be protected.

I recall a large N. red oak in Bullard Woods measuring close to 14 feet in circumference if my memory serves me correctly. [Bob will be visiting Bullard Woods and checking to see if this tree still stands] Its height is around 100 feet–again, if my memory is correct. Assuming those dimensions and using the Forest Service’s FIA-COLE volume-biomass model, that oak has an estimated above-ground dry biomass of 26,679 lbs. Another 15% can be added for underground roots giving 30,681 lbs. Approximately 50% of this dry weight is carbon or 7.7 tons. This amount of carbon has a CO2 equivalency of 28.2 tons.

How do we interpret this amount of carbon? One approach it to consider what it would take to replace it with new growth. Let’s say we have a 12-inch DBH [Diameter at Breast Height], 50-foot tall young N.[Northern] red oak. Including roots, its dry biomass would be an estimated 871 lbs. of which 435 are carbon or 0.22 tons. It would take 35 young trees to match the carbon of the one large oak. Keeping the 35 in mind, the next calculation may come as a real surprise. Using a 6-inch DBH, 40-feet tall oak, the number of young trees needed to match the one big tree soars to 175! Finally, let’s drop to a 4-inch DBH and 25-foot height. The number of oaks required skyrockets to 472! It takes 10 or more years to get a young red oak up to this size. In the time we have left to get the climate crisis under control, we can’t plant our way out of it. So, places like Bullard Woods take on added importance. For me, the lesson is clear: save big trees where possible.”

April 2021