pH-sensitivity in boreal streams – the influence of landscape characteristics

Abstract: The goal of the society to increase the proportion of renewable energy has led to an increased demand of bioenergy e.g. forest biomass. However, there are concerns that removal of biomass will lead to decreased base cation concentrations in the soils and acidification of streams. In order to find in which types of landscape removal of branches and tops could have such negative effects, this study aims to analyse the relations between pH-sensitivity and landscape variables in the Bothnia Bay water district. GIS and digital geographical data were used to analyse the landscape in subcatchments. This data were analysed together with stream water chemistry data by using principal component analysis. The results indicate differences between the north and south parts of the district. In the northern subcatchments, pH-sensitivity was positively correlated to water surfaces and coarse quaternary deposits with Scots pine forests. In the south, pH-sensitive streams were positively correlated to till soils and the concentrations of total organic matter (TOC). In both areas, alkalinity and ANC were the most important factors indicating that the buffering capacity primarily was due to weathering.