Newswise — Foresters have known for decades that restoring native Longleaf pine forests would help reduce the risk of the large fires plaguing Florida today.
That's because the Longleaf forests — actually, open savannahs characterized by widely spaced stands of the majestic trees — never experience the kind of intense flames consuming hardwood forests and pulpwood plantations today. But it has been difficult to find an incentive beyond sound land management to plant widely spaced Longleaf pines or to thin overly dense stands.
Now, a University of Florida botany professor thinks he may have a solution.
In a paper appearing this month in the journal Restoration Ecology, UF botany Professor Jack Putz argues that hardwood trees removed to restore Longleaf pine ecosystems could be used as fuel to generate electricity. The hardwoods that invade after fire suppression could be burned in generators, a practice that already occurs at some sawmills, or converted to cellulose-based ethanol once that technology improves in the future. Such energy is "greenhouse gas neutral" because it emits no carbon from fossil sources.
"People are looking for solutions and there are not many around, other than consuming less energy," Putz said. "But here's a solution to three problems: restoring our native Longleaf pine savannas, boosting clean energy and reducing fire risk."
Firefighters in drought-stricken Florida have been battling the worst wildfires since 1998 for weeks. Putz said one reason the fires are so intense is that much of Florida's forests are too dense, filled with hardwoods such as laurel oaks, water oaks and sweet gums. Fire suppression efforts have only encouraged these hardwoods. While native, the result is that the expansive Longleaf pine forests common when settlers first arrived in Florida have largely disappeared. Just 3 percent remains of the original Longleaf pine ecosystem of more than 91 million acres in the southern U.S.
The problem with dense stands of hardwoods and pines is that they burn intensely all the way up to their tops, or crowns, a problem made worse by years of forest fire suppression. Fires in Longleaf pine forests, by contrast, are slow, low, and creep along methodically consuming grass and brush at one- to three-year intervals. Such fires rarely, if ever, become menacing conflagrations.
Foresters have been actively restoring Longleaf pine forests in small selected areas throughout the Southeast for some time. A common hitch, Putz said, is that the first step of getting rid of a site's hardwood trees is both expensive and polluting. That's because foresters might burn the hardwoods, which results in carbon emissions, smoke and ash, or truck them off site to a landfill, which is energy intensive and expensive.
"The problem is you are releasing carbon into the atmosphere without using it to generate electricity," he said.
Some landowners have begun grinding up unwanted hardwoods into fuel chips. The chips are then burned, usually at sawmills, to produce electricity " electricity sometimes fed back into the grid when the sawmill is idle. Putz and co-author Brian Condon, a student in UF's food and resource economics department, analyzed 13 North Florida restoration projects producing such fuel chips with electricity production in mind.
Their chief finding: The amount of carbon harvested in the chips greatly exceeded what was consumed in the diesel used during harvest and transport, meaning the process "offsets" carbon. Not only that, but four projects actually earned a profit selling the chips, while four others paid much of their cost, meaning such activity may also be attractive economically.
Robert Hutchinson, project manager at Alachua Conservation Trust, a land conservation group, and former executive director of the Southeastern Forest Trust, said the idea is a good one when it comes to providing incentives to restore natural ecosystems.
"Increasingly, rural landowners are looking at combinations of funding sources to pay for restoration or for preservation, including carbon sequestration, conservation easements, non-timber forest products, wetland mitigation and ecotourism," he said in an e-mail. "Biomass fuels, at their best, can be used to improve the bottom line for ecosystem restoration."