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

Abstract

A study was conducted to evaluate the effects of restoration practices in a forest ecosystem near the Ulsan Industrial Complex in southeastern Korea. The calcium and magnesium contents in the soil, as well as the soil pH, increased after the application of a soil ameliorator but decreased again after 20 years. Meanwhile, the aluminum content presented the opposite trend. After restoration, the species composition and diversity of vegetation tended to differ from that of the non-restored site over time while continuously becoming more similar to that of the reference site. The ratio of exotic plant species was lower than that at the non-restored site but higher than that at the reference site. The frequency distribution for the diameter class of oaks established through restoration presented a reverse J-shaped pattern, and thus, they can be maintained continuously; similar results were obtained for the reference site. In sum, the forest ecosystem near the industrial park—which had been severely degraded due to air pollution and soil acidification—was restored to a forest close to natural conditions through restorative treatments, including the neutralization of acidic soil and the introduction of tolerant species.