Monitoring atmospheric deposition in Flemish forests

The intensive forest monitoring network (Level II) in Flanders operates under the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests, www.icp-forests.org), which is part of the Working Group on Effects (WGE) and follows the UNECE Convention on Long-Range Transboundary Air Pollution (CLRTAP, 1979).
The Flemish Level II network consists of 11 Level II plots (5 \core\ plots and 6 \additional\ plots). In the core plots, deposition, soil solution and litterfall are followed up on a halfmonthly basis since 1994, besides a large number of surveys conducted at a lower frequency, according to the guidelines of the ICP Forests Manual. The following forests host the five Level II core plots, which since 2014 are also LTER-Belgium sites:
• Ichtegem - Wijnendale Forest (Fagus sylvatica L.)
• Ravels Forest (Pinus nigra subsp. laricio var. Corsicana Loud.)
• Brasschaat - De Inslag (Pinus sylvestris L.)
• Gontrode - Aelmoeseneie Forest (Quercus robur L., Fagus sylvatica L.)
• Sonian Forest (Fagus sylvatica L.)
The collected data can be used for the six-yearly assessment of the conservation status of a number of forest habitats in Flanders with European protection under the Natura 2000 Habitats Directive. The long-term data series also allow to evaluate long-term trends of the deposition of acidifying and eutrophicating compounds (sulphate and inorganic nitrogen) in Flemish forests, which is relevant with regard to emission abatement policies at the European and the Flemish level (e.g. NEC Directive, VLAREM II, ...). Furthermore, the long-term data series allow to evaluate the evolution of forest ecosystem status with regard to acidification, N eutrophication, and certain effects of climate change (drought, higher temperatures, ... ) in forest ecosystems. The Level II plots and the long-term data series are also valuable for (inter)national data-evaluations en fundamental scientific research in cooperation with local and foreign universities en research institutes.

Overview of the different surveys in the 5 Level II core plots.
• Soil chemistry
• Ground vegetation
• Forest inventory
• Growth
• Crown condition
• Atmospheric deposition
• Soil solution chemistry
• Soil humidity
• Soil water level
• Litterfall
• Tree mineral nutrition
• Meteorology
• LAI
• Phenology
• Air pollutant concentrations (O3, NH3)
• Soil temperature