Intensive forest biomass harvest and need for nutrient compensation – new knowledge for guidelines for sustainable biomass utilisation

To meet a future fossil-free bio-based economy utilisation of forest biomass will have a leading role. Available forest biomass depends on available areas, biomass reserves, growth rate and harvest intensity.

Whole tree harvesting, harvesting of stems and branches/tops (brash), has been shown to reduce tree growth compared to stem only harvesting. Following incineration ash can be returned to the forest to compensate for increased acidity and nutrient loss (except nitrogen). Depending on site quality the effect of ash return varies. Key issues to explore further are how harvest intensity affects long-term forest production and if nutrient compensation is needed for a sustainable primary production of biomass. The experimental basis is limited, and more knowledge is needed mainly about effects on different soil types and the duration of effects. This project will contribute to improved understanding of long-term effects important to design guidelines for sustainable biomass harvest.