Regional fördelning av skogsskador i förhållande till mängd SO2 under vegetationsperioden i norra Tjeckien
Sammanfattning: During the last decades the forest damage in the Black triangle region (where the borders of the Czech Republic, Germany and Poland meet) has increased rapidly. Many attempts to explain the widely spread damage has been done. To quantify the risk of damage, the expression "critical level" has been introduced. Critical level is the highest concentration of an acidifying compound that the air can contain, without damaging the ecosystem in the long term. The forest damage is proportional to the ratio of SO2-concentration and vegetationperiod, and the critical level is 0.07 nPa/Pa/dag. The aim of this study is to investigate if this theory is applicable in a regional scale, and to quantify the area which is exceeding the critical level. An error propagation analysis was also to be calculated to be able to evaluate the results. The study area is approximatly 13850 km2 i the northern part of the Czech Rebublic. The S02-concentration data is modelled values. Measured SO2-concentrations from 1971-1990 were used to compare with modelled values from 1992. Damage degree and salvage cutting (1985, 1990 and 1995) of 19 forest enterprises were compared with the forest damage and the SO2-concentration/vegetationperiod. The comparison showed high negative correlation with damage in category l, and high positive correlation with damage in category 3. Small permanent plots with forest damage data from 1992, were compared with SO2-concentration/vegetationperiod. The correlation coefficient (-0.078) did not support that the forest damage is propotional to S02-concentration/vegetationperiod. This could be that the permanent plots are small compared with the geometric resolution in the S02-concentration data (13.5 ' 13.3 km). Error propagation with an error in the modelled data of ± 20% and ± 50% and an error in the vegetation period data of ± 10% resulted in an error of + 33% to (-27%) respectively + 67% to (-55%) in the ratio SO2-rconcentration/vegetationperiod. This means that in the best case, 87% (1250 km2) to 95% (13160 km2) of the area is below the critical level. In the worst case, 80% (11080 km2) to 100% (13850 km2) of the study area is below the critical level.
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