Volatile oil prices, concerns about carbon dioxide emissions, and catastrophic wildfires have created new interest in removing wood from forests as an alternative energy resource. In response, states from Maine to Missouri are developing guidelines for the harvest of forest biomass (logging slash, small-diameter trees, tops, limbs, or small trees). A new report by the Forest Guild, An Assessment of Biomass Harvesting Guidelines, is the first comprehensive review of these biomass harvesting guidelines. A working group of guild members reviewed and improved the report. The report also provides recommendations to ensure that new guidelines promote sustainable use of biomass from forests.

Forest harvesting guidelines provide foresters and loggers advice on how to remove woody biomass and how much should be left in the woods for healthy watersheds, wildlife habitat, protection of long-term productivity and other ecosystem functions. Previously developed forest practice guidelines by states did not anticipate the increased removal of biomass and thus offer no specific guidance on removal limits needed to keep forests healthy.

“New interest in woody biomass is a double-edged sword,” says Dr. Zander Evans, Forest Guild research director and the report’s author. “If harvested sustainably, biomass can meet some of our energy needs and leave our forests healthier than they are now. However, without appropriate guidance, biomass harvests can seriously degrade our forests.”

In general, wood that would have been left on-site under traditional harvest conditions is removed in a biomass harvest, which can mean a reduction of dead wood. Dead wood plays an important role in the ecosystem by providing wildlife habitat, cycling nutrients, aiding plant regeneration, decreasing erosion and storing carbon. The reduction of dead wood is one of the key differences between biomass removal and traditional harvest; it should be a focus of future guidelines. Guidelines should make clear and specific recommendations to retain standing dead trees (snags), existing coarse woody material (CWM), harvest-generated CWM, fine woody material (FWM), and the forest floor and litter layer.