Woodland restoration: Burn piles, biochar, and carbon credits

By Jeff Gahris

I have long enjoyed winter woodland restoration projects, removing invasive honeysuckles and buckthorn. This work is critical if we want thriving oak forests in DuPage County. But I have often asked myself, why do we have to burn all of this biomass? Given the release of carbon and various air contaminants, I ask: Is there a better way?

A burn in progress at Churchill Woods Forest Preserve

Standard procedures have been used for years by professionals who restore natural areas. Invasive plants have a lot of biomass, so some sort of disposal is needed. Also, it is helpful to dispose of the berries to reduce the sprouting of new invasive plants.

Meanwhile, there is a growing interest in biochar. Biochar is simply wood that is reduced to carbon by incompletely burning, often in an oxygen-starved combustion unit (pyrolysis). It can be used as a soil amendment in agriculture and a means to permanently sequester carbon to address the climate crisis.

Biochar from invasive plants is being studied in China to use as a soil amendment in grassland restoration projects to help restore soil health. However, studies have shown limitations in using biochar as a soil amendment, depending on the situation. Often, the microbiology in soils is not enhanced by the application of biochar, and plants may not respond to its presence.

Locally, there is growing interest in receiving carbon credits for planting trees, restoring natural areas, and conserving existing natural areas. There is even a nonprofit carbon registry called City Forest Credits that manages the purchase of carbon offsets for local municipalities and land preservation organizations. I’m intrigued by the possibilities, knowing that we can meaningfully measure how much carbon is absorbed by current conservation and restoration efforts by public and private landowners. Given that carbon is released from burn piles, another intriguing opportunity would be to start a pilot-scale biochar project in northeast Illinois. Between tree trimming and invasives removals, we certainly have enough feedstock for a biochar operation.

I am interested in your ideas on this complex topic and look forward to hearing from you. Send me an email to jgahris@gmail.com.