Managing Biomass on Forest Floors

Additional Resources Types of Pine Cones Biomass Energy

Have you ever taken a walk in the forest and thought that the forest floor looked a bit messy and concluded that someone ought to clean it up?

Probably not. Common wisdom tells us that the components of the forest floor, including broken branches, leaves and woody plants are a natural part of a forest ecosystem that contribute to an overall healthy forest. Downed trees, branches and leaves eventually decompose, adding fertility to the forest floor.

Renewed interest in biomass energy and renewed concerns regarding the severity of Western wildfires have led to a re-examination of the common wisdom about leaving the forest floor alone.

The publication Environmental Effects of Forest Biomass Removal addresses the question, and reviews recent research covering the relationship between biomass removal and its effects on forest plants, wildlife, soil and air quality.

With respect to plant life, for example, the authors state:

"A major concern with thinning or woody biomass removal is the potential for such activities to introduce and/or spread invasive exotic species. Greater frequency and abundance of exotics in thinned compared to unthinned stands has been reported in several studies; effects that can last for decades and lead to significant management costs in their own right. The degree to which thinning favors desirable native or invasive exotic species depends to a large extent on the seed species present in the soil, and on how the seed bed is treated after thinning.

Kerns and others.. conclude that variable density thinning prescriptions show promise for increasing the biodiversity of understory plants, fungi, native mosses, lichens, ferns and herbs."

Their analysis of the effects of forest biomass management on wildlife spans many areas including mammals, birds and amphibians. With respect to bear populations, the authors state,

"Black bears use areas with abundant down wood and dense thickets of shrubs and smaller trees adjacent to or within mature forests. About 25% of black bear diet can consist of insects (mainly ants and yellowjackets) obtained primarily from down logs...so decreases in down wood can make less of this food available to black bears.

Generally speaking, the authors attempt to provide a balance of the potential negative and positive effects associated with forest floor management. Their systematic review, while not providing many definitive conclusions, does provide insight into the future of forest management.

© 2009 Patricia A. Michaels