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Brussels, 7 October 1999

Report on forest conditions in Europe 1999 : No improvement of the vitality of European Forests

The results of the 1998 forest health survey show a general deterioration of the crown condition of the main tree species; the trend of the forest condition is comparable with that of the past years. This long-term development must be seen differently for each species of tree and for each individual region. While the vitality of the Pine in parts of Eastern Europe has been recovering the condition of common and sessile Oak in Western Europe has clearly been deteriorating. It gets more and more apparent that photooxidants, with ozone as the main substance, can lead to visible damage in forests. This is particularly true for the Mediterranean. Ozone damage is to be suspected in other regions as well. On average the crown condition (defoliation) in Europe between 1992 and 1998 worsened on approximately 31% of the observation plots and improved on only 15% of the plots. The main causes of the vitality losses and damages are air pollution (direct and indirect) and extreme droughts.

Results of the crown condition assessment

The following table shows the percentage of assessed trees in the different defoliation classes. Throughout Europe 35.1% of the assessed trees are classified as "healthy", about 40% are in the "warning stage" and a quarter of all trees are rated "damaged", since they show more than 25% defoliation. The degree of damage (all trees with more than 25% defoliation) is the same for conifers and broadleaves.

    Tab.: Proportional distribution of the defoliation classes for conifers, broadleaves and all tree species in 1998

Species slight


"Warning stage"

> 10-25%


> 25-60%


> 60%

EU Broadleaves


All species
















Europe total Broadleaves


All species
















Intensive monitoring programme

It is generally known that the effects of the stress factors having an impact on forest health are complex and are clarified through specific research on ecosystem level in long-term studies.

Some main findings of the recently completed Technical Report 1999 "Intensive Monitoring of Forest Ecosystems in Europe" can be summarised as follows:

  • Approximately 20% of the soils in Europe are very acid. Extremely acid soils are mostly located in Central Europe, the area with the highest air pollution and the highest defoliation of trees.

  • Half of the surveyed plots, this is mostly located in Western Europe, showed an increased nitrogen deposition (>15kg/a/ha). This nitrogen deposition leads to increased nitrogen contents of needles and leaves.

  • Ozone causes visible damage in forest ecosystems; mainly affected seems to be parts of the Mediterranean.


In 1985 the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on forests (ICP Forests) was created. This took place within the framework of the Convention on Long-Range Transboundary Air Pollution (Geneva Clean Air Convention, UN/ECE). In 1986 the Member States of the European Union (EU) agreed on the European Union Scheme on the Protection of Forests against Atmospheric Pollution (Regulation (EEC) No 3528/86). The participating countries decided to obtain information on the forest condition through a common monitoring in two intensity stages:

  • The extensive monitoring on a systematic sample network includes the annual assessment of crown condition of the trees, their nutrition and the forest soil condition on an extensive scale. This monitoring intensity stage is designated as "level I" and was created in 1987 with the crown condition assessment. The principal goal of level I is to obtain information on the development of the crown condition on European scale in connection with possible causes including air pollution. The extensive monitoring on level I covers at the moment about 5,700 plots in a systematic 16x16 km sample network representing 127,000 trees. At the surveys all European Union (EU) Member States as well as 15 Non - EU countries take part.

  • The intensive monitoring assesses in addition to crown condition, soil condition and nutritional status assesses increment, vegetation, deposition and meteorological conditions in detail. This intensive monitoring stage is called "level II" and exists since 1994 (regulation (EC) No. 1091/94). The principal aim of level II is to obtain information about development and relationships between location and stress factors on the one hand and the forest condition on national and European level on the other hand. For the time being the number of permanent level II observation plots is 860. The monitoring of the forest ecosystems is part of the implementation of the forest strategy of the EU, which was adopted by the European Council on 15 December 1998.


The results of 13 years forest condition monitoring contributed to the fact that many European countries as a consequence of the implementation of the Geneva Clean Air Convention and the EU- legislation including the implementation on Member state level have reduced the emissions of air pollutants. Still further reduction measurements are needed to keep our forest ecosystems stable.

Besides the effects of air pollution on forest ecosystems aspects such as bio-diversity in forests, protection of our climate as well as the implementation of the resolutions of the Ministerial Conferences on the Protection of the Forests in Europe gained political significance. In future the Europe-wide programme to monitor forest condition will contribute to these aspects.

More information can be obtained from:

European Commission    DG VI/F.I.3  Rue de la Loi 130  B-1040 BRUSSELS  Belgium   

FAX: 00 32 2 296 62 55

Federal Research Institute for Forest and Timber Economy  PCC of ICP Forests  Leuschnerstr. 91  D-21031  HAMBURG  Germany  

FAX: 00 49 40 739 62/480

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