Abstract
This study was carried out to clarify the vegetation decline due to air pollutants emitted in the process of industrial activities and the passive restoration of the vegetation due to socioeconomic changes after economic growth. To achieve this goal, we investigated the spatial distribution of vegetation, differences in species composition and diversity among vegetation types different in damage degree, vegetation dynamics, the age structure and annual ring growth of two dominant plant species, and the landscape change that occurred in this area over the last 50 years. Plant communities tended to be spatially distributed in the order of grassland, shrubland (dominated by Styrax japonicus Siebold and Zucc. community), and forests (dominated by Pinus thunbergii Parl. and Pinus densiflora Siebold and Zucc. communities), with increasing distance from the pollution source. The result of stand ordination based on vegetation data reflected the trend of such a spatial distribution. Species richness evaluated based on the species rank dominance curve was the highest in shrubland and the lowest in grassland; species richness in forests was intermediate. The size class distribution of woody plant species in four plant communities composing three vegetation types showed the possibility of them being replaced by forest in the late successional stage. However, the density of successor trees was relatively low, whereas the density of shrubby plants, which are resilient to air pollution, was very high. The age class distribution of a dominant species forming shrubland and pine forest showed that most of them were recruited after industrialization in this area. The period when young individuals in both vegetation types were recruited corresponded to the period when the annual ring growth of the pine trees that survived air pollution was reduced. An analysis of the landscape change in this area indicated that coniferous forest and agricultural field decreased greatly, whereas industrial area, residential area, mixed forest, and broadleaved forest showed increasing trends since construction of the industrial complex. As a result, the decrease in coniferous forest is usually due to vegetation decline and partially to succession, as the pine trees dominating the forest are not only sensitive to air pollution but are also shade-intolerant. The increase in mixed and broadleaved forests reflects vegetation decline or succession. Vegetation decline progressed for about 30 years after the construction of the industrial complex; it has begun to be restored passively since then, although the change has been slow. These results are in line with the environmental Kuznets curve hypothesis that environmental degradation increases in the early stages of economic growth to a certain point, and, after a turning point, economic development leads to environmental improvements—thus, there is an inverted U-shaped relationship between economic growth and environmental degradation.
Highlights
Air pollution, which occurs when concentrations of substances in the air are elevated above typical background levels, causes measurable and undesirable effects on organisms and/or ecosystems [1,2,3,4,5,6,7,8].Air pollutants come from natural sources, such as volcanic activity and forest fires, and from large-scale anthropogenic emissions
Communities corresponded to the period when the annual ring growth of the pine trees that survived. Forest in this area before the construction of industrial complex was usually coniferous, dominated by air pollution was suppressed (Figure 6). These results suggest that most individuals in these two the Korean red pine (P. densiflora) community and partially mixed with black pine (P. thunbergii) depending communities are the products of air pollution damage and natural regeneration of damaged forest
We reached to the following conclusion from the analyses on the spatial distribution of vegetation, differences in species composition and diversity among vegetation types different in damage degree, vegetation dynamics, the age structure and annual ring growth of two dominant plant species, and the landscape change that occurred in this area over the last 50 years
Summary
Air pollutants come from natural sources, such as volcanic activity and forest fires, and from large-scale anthropogenic emissions. Examples of the latter include industrial processes such as metal smelting and refining, the production of commercial energy through the burning of fossil fuels, and the use of fossil-fueled engines for transportation [1,9,10,11,12]. Industrial and urban regions of Korea have experienced high concentrations of air pollutants, which in some cases have caused significant ecological effects, including damage to forests, like in other developed countries of the world [1,14,15,16,17,18]. In cases involving exposure to high concentrations of pollutants emitted by discrete point-sources, the damage is most severe close to the point-sources, and decreases in a more or less geometric fashion with increasing distance from the source [1,2,24,25,26]
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