Decline and Passive Restoration of Forest Vegetation Around the Yeocheon Industrial Complex of Southern Korea

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.

Evaluation of the 20-Year Restoration Process in an Air-Pollution-Damaged Forest near the Ulsan Industrial Complex, Korea

“…Such vegetation mats monopolize resources such as light, nutrients, and water, hindering the progression of succession and the establishment of other species [61], as has been demonstrated in the inhibition model of Connell and Slatyer [62]. The decline of such vegetation mats indicates the resumption of succession [63][64][65] and can be considered a positive indicator of successful restoration [1,66,67].…”

“…Significant material and energy resources are used in human activities, especially in industry. As a result, such activities tend to generate a significant amount of pollutants, often exceeding the limit of the buffering capacity of the location where the activity takes place and causing damage to the vegetation and soil of the area [1][2][3]. If the imbalance between the pollution source and the buffering capacity worsens, the vegetation will decline, and if it worsens further, desertification may finally occur.…”

“…In addition, the function of carbon-absorption sources (which absorb and remove the carbon dioxide (CO 2 ) emitted by industrial activities) may deteriorate, resulting in exaggerated differences between the emission and absorption of carbon [7]. Therefore, it is necessary to restore damaged ecosystems in order to prevent the spread of such damages [1,5,8].…”

Passive Restoration Achieved through Natural Processes over 70 Years in the Korean DMZ

“…Therefore, the widths of most rivers and/or streams were greatly reduced. Further, many of those rice fields were not only again transformed into urbanized areas, including residential areas, but also meandering and complex channels were changed to straight and monotonous ones in urban areas [4][5][6][7]. In such continuing transformation processes, riparian communities have been greatly degenerated or destroyed by tree cutting, the introduction of exotic species, the diversion and channeling of water for agriculture, and the use of river beds and shores for cultivation or even as roads.…”

Climatic and Anthropogenic Contributions to Vegetation Changes in Guangdong Province of South China

“…On the one hand, industrialization and urbanization usually cause vegetation degradation and vegetation loss. For instance, forest vegetation decline has lasted for 30 years since the construction of industrial complexes in southern Korea [28]. Urban expansion widely resulted in vegetation degradation around urbanized regions, such as the Beijing-Tianjin-Hebei Region [27], the Yangtze River Delta [5], and the Pearl River Delta and Shantou city of Guangdong Province [9].…”