A burgeoning interest in harvesting woody biomass from forests around the country is a double-edged sword, according to a leading forest researcher.

“If harvested sustainably, biomass can meet some of our energy needs and leave our forests healthier,” said Zander Evans, who recently co-authored a report for the Forest Guild that outlines guidelines for sustainable biomass harvests. ...

“However, without appropriate guidance, biomass harvests can seriously degrade our forests,” he said.

Harvesting biomass essentially means removing downed and dead wood from the forest that would be left in place during traditional timber harvests, which focus on removing large and healthy trees to produce lumber and other wood products.

But removing too much of the material can have negative effects on wildlife, water quality and forest soils.

Woody debris on the ground provides wildlife habitat, helps fix nitrogen in the soil, aids plant regeneration, stores carbon and slows the flow of water to reduce erosion, Evans said.

Most studies on biomass removal have focused on Eastern hardwood forests.

“We haven’t seen that much information for fire-adapted forests,” Evans said.

Local application

In Summit County, local and federal officials have been trying to find economic value for vast areas of forests killed by mountain-pine beetles.

A plan to heat some county buildings with biomass was discarded last year because it was deemed too expensive.

For now, some of the woody debris is being converted into pellet fuel at a factory in Kremmling.

But given the amount of biomass available, there is interest in using the material for energy production. A planner with a Fort Collins-based company recently attended a local meeting to ask how much wood might be available.

Getting a ballpark estimate on the quantity of potential fuel is the first step toward considering significant investments, said Phil Schwolert, director of biomass fuel procurement for Novo Development Co.

Determining how much woody debris should remain in the forest is a big part of coming up with the answer to that question.

U.S. Forest Service timber specialist Cary Green said the agency estimates that the beetle epidemic could create between 60 and 120 tons of biomass per acre. Forest plan guidelines call for leaving five tons per acre, but the agency prefers to leave between 10 and 15 tons per acre.

According to the Forest Guild report, meaningful biomass-harvesting guidelines should be based on local forest ecology and should reflect a consensus of a broad range for forest stakeholders related to practices that will sustain a high level of biodiversity.

Biomass plants should be designed and built on a community scale to ensure sustainability, Evans said, adding that his group envisions several buildings in local communities powered by biomass fuels.

Building large, centralized facilities with a “voracious” appetite for fuel could increase pressure for unsustainable harvests, he said.