Results of a study of vegetation cover of tundra ecosystems influenced by dwarf pine plantations of the age over 20, 40, 60 and 90 years, located on the ridge areas of sub-alpine zone in the western Giant Mountains is submitted. The observation of 5 permanent plots (Labská louka meadow, near state border, U čtyř pánů crossing-road, Harrachova louka meadow, N slope of Kotel Mt.), using both semi-quantitative and quantitative phytosociological methods, resulted into findings that the proportions of above-ground biomass of dwarf pine plantations, depending on its age, ecological conditions and surrounding phytocoenosis type, has a negative influence on the biodiversity of these ecosystems, including the negative influence on the microgeomorphology of the soil terrain.