Impacts of Forest Biomass Removal on Soil Quality and Biodiversity
The nation's forest lands contain excess biomass that could be utilized for advanced biofuel production. Removing forest biomass from young, overstocked forest stands for production of biofuel decreases wildfire hazards, improves resistance to pests and disease, and accelerates development of large diameter trees. Using forest lands for biofuel creates products that will not compete with demand for food. However, biomass removal also takes away nutrients and organic matter from the soils that support future forest growth and provides nourishment to the forest food web of microbes, insects, snails and slugs that are in turn consumed by birds and mammals. Available science suggests that there is little impact of biomass removal on forest soil and future productivity from timber harvesting. Yet, there is little information on biomass removal from
young, small-diameter forest stands and even less information on how removals from younger forests affect the diversity of wood decomposing fungi and ground dwelling insects and gastropods. It is especially important to understand the impacts of removals from small-diameter forests. A significant proportion of available forest biomass occurs in young overstocked stands. Thinning forest at this stage of development has significant positive impacts on forest growth and structure that affect forest health and vigor for decades. This study assesses the impacts of removing various amounts of excess biomass from small diameter forests on tree growth and vigor, soil quality, microbial activity, and the diversity of wood decay fungi, insects and gastropods. We will consider how amendments such as fertilization and charcoal (biochar) might mitigate responses to biomass removal. We expect to see
little impact of removing biomass on soil properties and forest growth, but we expect that diversity of forest fungi, insects and gastropods will be sensitive to removal of biomass. Fungal and invertebrate communities should change in measurable ways, but it is not clear how this will affect their community diversity. Fertilizer and biochar amendments are expected to largely compensate or supersede any observed removal impacts especially for soil physical, chemical and biological properties. In combination, our research will provide important indicators of the impacts of biofuel production on forest ecosystem sustainability. It will establish initial guidelines on the amount of biomass retention required to maintain critical ecosystem functions in western forests, and it will demonstrate ways to compensate or enhance those features through use of soil amendments. The biomass retention
requirements will guide forest biomass removal for biofuel production and assure that future generations receive similar goods and services that we have traditionally enjoyed from our abundant forest ecosystems.