Undergrowth as a biomonitor for deposition of nitrogen, acidity and dust in pine forest

The aim of the research was to analyse changes in ground layer of Scots pine (Pinus sylvestris L.) stands under the impact of acidifying, eutrophying and alkalizing local pollution. The main research objectives were to characterize the current state of the forest ecosystems on the basic of their composition and to compare the abundance of plant species in the stands in the different impact zones and with data from background areas. Species composition of the understorey of Vaccinio-myrtillo-Pinetum forest type ecosystems was studied in the impact zone of acidifying and eutrophying “Achema” pollution and it is concluded that plant communities is changed in the forest ecosystems. Species number almost in all affected sample plots was higher in comparison with the control (p<0.05). Many non-typical nitrophilic species (Rubus idaeus, Chelidonium majus, Chameriom angustifolium, Moehringia trinervia, Galeopsis tetrahit) preferring nutrient-rich sites and acidophilic species (Rumex acetosella L., (Festuca ovina) increased in cover in the vicinity of “Achema”. Cover of species typical for Vaccinio-myrtillosa site type (e.g., Vaccinium myrtillus, V.vitis-idaea) increased with the distance from “Achema”. In the impact zone of alkalizing “Akmenes cementas” pollution sample plots of Myrtillo–oxalidosa turfoso–siccata forest type changes in ground vegetation were significant and certain. The number of bryophytes species was significantly lower in the heaviest impact zone (0.5-3.5 km) comparing with the control (p