Air Pollution Bioindication by Means of Epiphytic Lichens

1991

S. 248-254

6 Abb., 7 Lit. Ang.

Unselbständiges Werk

200044694

Epiphytic lichen vegetation has been used as air quality bioindicator in the forest die-back inventories since 1985. The simplest method of epiphytic lichen bioindication was accepted, i.e. the mapping of crustose, foliose and fructicose lichens in forest die-back inventory plots. For each thallus type the frequency and coverage were established separately at three heigts of trees trunks (0-0,5 m, 0,5-2,5 m, 2,5-up to crown). From the data obtained, the index of atmospheric purity was calculated representing air quality measure. The values of index were ranked into five classes like damages of forest trees and entered into the map of Slovenia. The lichen map of Slovenia represented well air pollution situation in comparison with measured pollutants in air (sulphur dioxide and dust) and the position of major emission sources (Batic & Kralj 1989). In forest die-back inventory carried out in 1990, the method of inventory changed, including that part concerning the establshment of epiphytic lichens. In earlier inventories (1985, 1987, 1989) the epiphytic lichens were observed in the whole inventory plot on unmarked trees. The observed trees were chosen according to their climatozonal value in the inventory plot and they ought to be also otherwise suitable for lichen observation (old enough, well lit, etc.) (Skye 1968). Because of this it was not possible to control or correctly repeat the lichen survey. Therefore, it was decided to link lichen survey to one group of six trees already marked for forest damage survey. In that case it was possible to repeat also the lichen survey and control work of field crews who carried out whole inventory. This change of method caused that the results of the inventory of 1990 were not comparable to results of earlier inventories anymore. Randomly chosen groups of trees in forest die-back inventory following the ECE methodology can be unsuitable for lichen observation because of being too young or growing in too shady a place. In spite of this it was decided to sacrifice a part of suitability of observed trees for the possibility of control and repeat of inventory. Beside that change, there was also a different calculation of the index of atmospheric purity. Using frequency and coverage establishment data for all lichen types, the index was determined separately for three heights of observation on the tree trunks as the average of observations on six trees and computed together as the index for the inventory plot. The results showed that according to the expectations the index of atmospheric purity was the highest at the bottom of the tree trunks (0-0,5 m) and the lowest in crowns. In mature forests, such situation clearly reflected the influence of polluted air. In general, the index of atmospheric purity was quite low on all strata as well as on the majority of the inventory plots. The situation was quite.....