Selection of air pollution tolerant plants through the 20-years-long transplanting experiment in the Yeocheon industrial area, southern Korea

To select a tolerant plant species for restoring a forest ecosystem that had been severely damaged by air pollutants discharged from the industrial complex, 26 sample plants were transplanted in the mountainous area around the Yeocheon Industrial Complex in southern Korea. This transplanting experiment has been in progress for 20 years from 1994 to 2013. Ten plant species died and 16 plant species survived during the transplanting experiment period. Among the surviving 16 plant species, we chose five species, Alnus firma, Eurya japonica, Styrax japonica, Ligustrum japonicum, and Sorbus alnifolia as the very tolerant species, and four species, Pinus densiflora, Elaeagnus umbellata, Quercus dentata, and Fraxinus rhynchophylla as the tolerant species. We prepared a vegetation map by interpreting aerial photographs for diagnostic assessment of the forest vegetation damaged by air pollution. We estimated grassland, shrubland, and forest on the vegetation map as vegetation types that were severely, moderately, and slightly damaged, respectively. To restore each vegetation type damaged at different levels, we prescribed very tolerant plant species that compose tree and shrub layers, tolerant species that compose a tree layer, and artificial aid at a minimum level for passive restoration of the grassland, shrubland, and forest zones, respectively. Additionally, we recommended E. umbellata, which can fix atmospheric nitrogen levels, as the fertilizer plant. We recommended S. japonica and S. alnifolia, which flourish in a disturbed and/or polluted environment, as species for protective planting in margin of a forest to be restored in grassland damaged severely.