Lunch Seminar "Is forest fuel harvesting sustainable – the role of base cation and phosphorous weathering" by Cecilia Akselsson

      The threat of climate change and its effects on ecosystem services and biodiversity has increased the demand for renewable energy. Harvesting of branches, tops and stumps in forests leads, however, to increased losses of important nutrients such as nitrogen (N), phosphorous (P) and base cations. Although N is often the limiting factor for forest growth in northern forest ecosystems, P and base cations can become limiting in areas with high nitrogen deposition (present and historical), e.g. in southwestern Sweden. Moreover, the loss of base cations may delay recovery from acidification, or even increase acidification. The risk of negative effects of P and base cation losses depends on the weathering rates. In this presentation the prerequisites for sustainable forest fuel harvesting in different parts of Sweden are discussed along with the role of weathering. Different methods for estimating weathering rates are also discussed and compared. It is concluded that increased biomass harvesting, especially in acidified areas, may lead to negative effects mainly on runoff water. Increased biomass harvesting and maybe also a climate more favourable for weathering may counteract this effect but this has to be further investigated.