European Community Forest Health Report 1989. Technical Report

Brüssel

1990

125 S.

27 Abb., 14 Tab., 5 Anh.

Bandaufführung

92-826-0438-1

12571

82193

The forest damage inventory programme started in 1987 with 1216 plots and 26390 sample trees. By 1989, the network had been enlarged to 1891 plots and 45572 trees, covering most of the total forest area of the European Community (EC) Member States (approximately 500 000 km2) by a 16x16 km grid. Observations in 1989 showed that 9.9% of the trees were damaged (defoliation more than 25%). The overall figures for the defoliation in 1987 and 1988 were respectively 14.3% and 10.2%. In 1989 a discolouration of more than 10% was observed for 16.0% of the trees. For 1987 and 1988 these figures (from smaller samples) were respectively 13.5% and 13.2%. Conifers were slightly more damaged than broadleaves. In 1989, a defoliation of more than 25% was found for 11.8% of the conifers and 8.4% of the broadleaves. Of the more common species found in the EC, the coniferous species Abies sp. and Picea sp. show the most defoliation with respectively 17.3% and 20.0% of the trees damaged. The broadleaves Eucalyptus sp. and Quercus ilex show the lowest degree of defoliation, with respectively only 1.6% and 3.5% of the trees damaged. Discolouration is approximately the same for broadleaves (16.3%) as for conifers (15.8%). The percentage of trees with a discolouration of more than 10% was highest for Quercus suber (45.8%). For Quercus ilex, this percentage was lowest (7%). Among the conifers, Abies sp. and Pinus sp. showed relative high percentages of discoloured trees with respectively 23.4% and 18.2%. With regard to the climatic zones, in 1989 the percentage of damaged trees was slightly higher in the Atlantic and Sub-atlantic regions (respectively 13.0% and 12.9%) as compared to the Mediterranean (7.0%) and Mountainous region (6.0%). The highest percentages for discolouration were found in the Mediterranean region (20.6%). Especially Castanea sativa, Quercus suber and Abies sp. show high discolouration figures with respectively 38.6%, 45.8% and 38.0% of the trees showing discolouration. Total percentages of trees showing discolouration in the Atlantic, Sub-atlantic and Mountainous region were respectively 14.1%, 10.3% and 14%. Easily identifiable damage due to known causes has been observed for 38.8% of the trees. For 10.9% of the trees more than one type of damage was identified. Insects were the most commonly identified damage type (19.1%) , known pollution was the least with 0.2%. A defoliation of more than 25% was slightly more observed for trees for which a damage type was identified (12.4%) than in trees were no identifiable damage was apparent (8.4%). The percentage of trees with a discolouration of more than 10% was clearly higher in trees where damage types have been identified (26.7% versus 9.3%). The most discolouration was observed in trees where damage from abiotic agents (wind, snow, frost, etc.) was identified (42.9% of the tree more than 10% ......