The forest damage inventory programme started in 1987 with a survey of 1216 plots and 26,390 sample trees. By 1989, the network had been enlarged to 1891 plots and 45,572 trees, covering most of the total forest area of the European Community (EC) Member States (approximately 500 000km2) by a 16x16km grid. With the reunion of the two German States another 115 plots were added in 1990. The total network in the EC-Member States consists now of 2005 plots with almost 50,000 trees. Besides the analysis and evaluation of the 1990 survey data from these plots, the data from forest health surveys in five Non-EC countries are also included in this Forest Health Report 1991. These data concern the forest vitality of almost 20,000 trees on 878 plots in Austria. Czechoslovakia, Hungary, Poland and Switzerland. Observations in 1990 showed that in the entire dataset (EC + Non-EC) 20.8% of the trees were damaged (defoliation more than 25%). The figures for the EC-Member States (including the former GDR) and the five Non-EC countries are 15.2% and 35.2% respectively. The overall figures for the defoliation in 1987, 1988 and 1989 in the EC (excluding the GDR) were respectively 14.3%, 10.2% and 9.9%. Similarly discolouration of more than 10% was in 1990 observed for 13.8% of the trees in the entire dataset and for 14.4% and 12.2% of the trees in the EC and Non-EC respectively. In 1987, 1988 and 1989 these figures were 13.5%, 13.2% and 16.0% respectively. Conifers were more damaged than broadleaves. In 1990, a defoliation of more than 25% was found for 24.2% of the conifers (EC: 15.6% and Non-EC: 38.4%) and 16.6% of the broadleaves (EC: 14.9% and Non-EC: 25.6%). Of the most common species found in the EC and Non-EC, the coniferous species Abies sp. and Picea sp. show the highest defoliation with respectively 18.8% and 21.2% of the trees damaged in the EC, while Abies sp. and Pinus sp. show the highest defoliation in the Non-EC countries with respectively 57.9% and 40.9% of the trees damaged. Conifers show less discolouration than broadleaves. In 1990, discolouration of more than 10% was found for 10.8% of the conifers (EC: 12.5% and Non-EC: 8.1%) and for 17.5% of the broadleaves (EC: 16.2% and Non- EC: 24.9%). The percentage of trees with a discolouration of more than 10% was highest for Qercus suber (48.4%). For Quercus ilex, this percentage was lowest (2.4%). Among the conifers, Abies sp. and Pinus sp. showed in the EC and Non-EC the highest percentages of discoloured trees with respectively 19.7% and 32.5% for Abies, and 15.0% and 11.0% for Pinus. With regard to the climatic zones, the percentage of damaged trees was considerably higher in the Non-EC Sub-atlantic region (36.6% as compared to the EC Sub-atlantic region (18.2%). For the Mountainous region this difference was less apparent (Non-EC: 15.8% and EC: 7.7%). The highest percentages for discolour....
