Report - ICP Forests

3. Intensive Monitoring 53
3.2.3 Conclusions
A high spatial variability of nitrogen and sulphur deposition could be detected in the present
study and confirms results found in earlier years (e.g. Lorenz et al. 2008, Lorenz et al. 2009). In
general, atmospheric sulphur and nitrogen deposition is higher in central Europe and some plots
in southern Europe as compared to northern Europe and alpine regions.
The prolongiation of the evaluation period which still relies on a sufficiently high number of
plots showed a more comprehensive picture of the temporal development of deposition across
Europe as compared to eaerlier evaluations based on shorter periods. Specifically for sulphur a
very clear reduction of deposition was observed in the period from 1998 to 2007. This trend is
less clear for nitrogen but also obvious at least in bulk deposition which is not influenced by
canopy interaction effects. The small share of plots with decreasing nitrogen deposition is in line
with Rogora et al. (2006) who investigated long-term deposition time-series from 1990-2002
and only found significant decreasing nitrate deposition trends for about half of the investigated
sites in the Alpine Arc. It even seems obvious that at least in some regions of Europe an increase
in nitrogen deposition is observed which should be analysed in more detail.
It has to be taken into account that Level II is not a statistically representative network.
However, the monitoring results reflect regional patterns and trends and partly regional
industrial air pollution. Due to the large number of plots and the wide geographical coverage it
is an important basis for monitoring air pollution effects in Europe. Increasing time series will
still enlarge the possibilities for more detailed data analyses in the forthcoming years.
The quantification of inputs through sea salt in coastal areas is a field for further methodological
improvements. The clear identification and quantification of canopy interaction processes also
require further development.
3.2.4 References
ICP Forests (2010): Manual on methods and criteria for harmonized sampling, assessment,
monitoring and analysis of the effects of air pollution on forests. UNECE ICP Forests
Programme Co-ordinating Centre, Hamburg [http://www.icp-forests.org/Manual.htm].
Lorenz, M., Fischer, R., Becher, G., Mues, V., Granke, O., Braslavskaya, T., Bobrinsky, A.,
Clarke, N., Lachmanova, Z., Lukina, N., Schimming, K. (2009): Forest Condition in
Europe. 2009 Technical Report of ICP Forests. Work Report of the Institute for World
Forestry 2009/1, vTI Hamburg 2009. 81 pp, Annexes.
Lorenz, M., Nagel, H.-D., Granke, O., Kraft, P. (2008): Critical loads and their exceedances at
intensive forest monitoring sites in Europe. Environmental Pollution 155, 426 - 435.
Lorenz, M., Becher, G., Mues, V., Fischer, R., Becker, R., Dise, N., Ulrich, E., Sanz, M. (2005):
Forest Condition in Europe. 2005 Technical Report. Geneva, UNECE, 72 pp, Annexes.
Rogora, M., Mosello, R., Arisci, S., Brizzio, M., Barbieri, A., Balestrini, R., Waldner, P.,
Schmitt, M., Stahli, M., Thimonier, A., Kalina, M., Puxbaum, H., Nickus, U., Ulrich, E.
& Probst, A., 2006: An overview of atmospheric deposition chemistry over the Alps:
Present status and long-term trends. Hydrobiologia, 562: 17-40.