Evolution of chemical soil quality in temperate forests under decreasing atmospheric deposition

In past decennia anthropogenic emissions and atmospheric depositions of nitrogen and sulphur compounds enhanced the acidification and eutrophication of forest soils in Flanders. Since the 1980’s international agreements like the Convention on Long Range Transboundary Air Pollution (CLRTAP) and the Protocol to Abate Acidification, Eutrophication and Ground-level Ozone (Gothenburg Protocol) (www.unece.org) induced a gradual reduction of acidifying and to a lesser extent eutrophying emissions in Flanders and the surrounding regions. Since 1987 Flanders participates in the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forest (ICP Forests) (www.icp-forests.org). Intensive forest monitoring plots (Level II plots) were installed at eleven locations. At five of these permanent plots (three in deciduous forest, two in coniferous forest) the concentrations and fluxes of pollutants and nutrients in atmospheric deposition, soil and soil solution are monitored continuously or at regular time intervals according to international standard procedures and methods. Currently, valuable long time series are available (1994 till now), which can be used for trend evaluation and for the study of relationships between measured variables. The five Level II plots are not representative for the entire forest area in Flanders, but they can be considered as valuable case studies for some of the most common forest types in Flanders.

The objective of this study is to evaluate the biogeochemical recovery in Flemish forests in reaction to the decrease of acidifying and eutrophying emissions. Trends and patterns of the concentrations and fluxes of the main inorganic ions (H+, Ca2+, K+, Mg2+, NH4+, SO42–, NO3, Al) in deposition and soil solution are studied. Trends and patterns of dissolved organic carbon (DOC) and dissolved organic nitrogen (DON) in deposition and soil solution are evaluated, with attention to the ratio between DOC and DON (DOC:DON). Modeling techniques are used to evaluate how the concentrations and fluxes of DOC and DON are influenced by a number of measured variables. Finally, evolution of forest nitrogen status will be evaluated more into depth, by means of the ratio between dissolved inorganic nitrogen (DIN) and DON (DIN:DON) and the ratio between DOC and nitrate (DOC:NO3).

Evolution of chemical soil quality in temperate forests under decreasing atmospheric deposition

Researcher: ir. Arne Verstraeten
Period: 2015-2016
Financing body: Inbo
Promoter: Prof. Stefaan De Neve and Prof. Steven Sleutel