Date of this Version
WIREs Energy Environ (2012) 1: 270–284 doi: 10.1002/wene.26
Water flowing from forested catchments, both unmanaged and managed, is highly valued in terms of both quantity and quality. Increasing energy production using wood feedstocks produces varying degrees of impacts and thereby raises concerns about environmental impacts on the highly valued water supply resources of forest ecosystems. The term water supply encompasses both key components of water quantity and water quality. Water quantity considers the amount of increases or decreases, timing, consistency, and relative magnitude of water yields. Plant nutrients (anions and cations), fertilizers, herbicides, ash additions, temperature, dissolved oxygen, pH, bacteria, and sediment comprise water quality. Within the life cycle of forest bioenergy, operational activities during stand establishment, midrotation silviculture, harvesting, product transportation, wood storage, energy production, and ash recycling create variable levels of impacts. Disturbance levels associated with bioenergy operations depend on their type, intensity, frequency, duration, timing, area of extent, and the level of best management practices (BMPs) employed for mitigating of soil disturbances. Feedstock growing, stand tending, harvesting, and wood transportation are considered nonpoint source disturbances since they occur over larger landscapes than energy production activities, which are usually localized at power plants. Water-quantity effects of forest bioenergy production are normally associated with vegetation management and related soil disturbances. Water-quality effects mostly occur as a result of soil disturbances during harvesting, the use of intra-rotation silvicultural chemicals (ash, fertilizers, and herbicides), and inter-rotation site preparation for forest regeneration. Using existing practices designed for environmental protection (BMPs), forest bioenergy programs are completely compatible with maintaining high-quality water supplies in forested catchments.