Landowners seeking to make money selling carbon credits while also continuing to sell timber have a new forestry technique to consider. A University of Vermont forest ecologist has developed a method he calls “structural complexity enhancement,” which maximizes carbon storage in trees and soils while allowing landowners to provide habitat for wildlife and harvest timber for profitable sale. It’s an approach that fosters characteristics of old growth by accelerating the rate at which the forest matures.
“This approach can let landowners restore old-growth forest habitats, fight climate change, and make a moderate amount of money – all at the same time,” said Professor Bill Keeton. “It’s a technique that emulates the natural disturbance processes that gradually encourage forests to develop late-successional characteristics.”
He said the specifics of the technique are somewhat complicated because a number of management procedures are used simultaneously. It includes harvesting about 40 percent less timber volume than conventional silviculture practices and leaving behind many of the largest trees; creating small gaps around the crowns of some trees so they achieve a large size faster; leaving some felled trees on the ground and pushing others over so they create mounds or pits; and girdling some trees to provide snags for wildlife.
“We also ensure that trees in each size class are left behind,” Keeton said, [which] retains more complexity in the forest, and builds up more biomass.” In 2001, he began testing the method at plots on the side of Mount Mansfield and at UVM’s Jericho Research Forest in northern Vermont. Every summer since then, a field crew has collected data from the trees, understory plants, and soils to compare against plots in which more conventional methods were used.
The results have been promising. Ten years after harvest, carbon storage was just 16 percent lower than it would have been had the forest not been logged at all; some of the conventionally managed timberland in the study blocks contained 45 percent less carbon than in the uncut forest.
“That difference represents revenue that the carbon market can pay you for,” Keeton said. “The key for a landowner is to optimize your revenue streams between carbon and harvest, making it advantageous to participate in the carbon market.”
Keeton acknowledges that his technique is not for everyone, noting that the carbon market is currently only financially viable for those owning or aggregating 1,500 acres or more. But it may be useful to land trusts, The Nature Conservancy, and other groups that manage large forests but for whom timber production is not the only objective.
It may also be of interest to managers of town and state forests. “Very rarely do they do just one thing with their forests,” Keeton said. “They do some commercial harvests, some habitat management, restoration work, integrated harvests, and in that context, this is another technique they can throw into the mix.” He also sees the technique as a way of fostering resilience against drought, higher temperatures, diseases, storms, and other ecosystem changes.