The expansion of forest biomass markets may affect California’s forests both positively and negatively. Existing research does not permit an exact assessment of biomass harvesting impact in each forest type, but policy decisions can still benefit from a synthesis of the available science. Biomass markets may permit the harvest and removal of trees that would previously have been left in the woods to die, so they may reduce the prevalence of key habitat elements such as snags and downed logs. Water quality, soils, and site productivity can also be affected by reductions in deadwood brought about by increased biomass harvesting. At the same time, new markets may allow for the restoration of forests that have become unnaturally dense because of fire exclusion (i.e., densities are outside the historic range of variability). Restoration can change fire behavior, and the removal of low-value trees can benefit the remaining trees. However, the retention of large pieces of deadwood can limit the risk of biomass harvests, impinging on biodiversity, while keeping small pieces of dead wood and foliage on-site can benefit water quality, soils, and site productivity.
