Soil acidification caused by anthropogenic activities adversely affects forest ecosystems by altering soil pH, which is an important factor in soil quality and function. Liming is one suggested way to solve this problem. This study was performed to evaluate the effects of liming in acidic forest soils by determining soil microbial biomass, microbial community structure, and extracellular enzyme activities associated with carbon, nitrogen, and phosphorus cycling. Lime treatment increased soil pH by up to 40%, significantly increased organic matter (OM) content at some sites, and altered the enzyme activity of the soil. With liming, the microbial biomass appeared to be affected by the chemical properties of the soil, such as pH, Ca²⁺, Mg²⁺, K⁺, and exchangeable aluminum (Ale) levels, although there were no significant differences at the site level. Enzymatic activity was found to be affected by pH, Ca²⁺, Mg²⁺, electrical conductivity (EC), and Ale; and acid phosphatase (AP) and phenol oxidase (POX) activity were significantly affected by lime treatment. AP activity decreased from 0.62 to 0.66, and POX activity increased from 1.75 to 3.00 in part of the sites. The bacterial community richness was influenced by pH as a direct effect of lime treatment. The fungal community richness was associated with changes in K⁺ that were not due to lime treatment. The bacterial community structure was affected by soil OM, total nitrogen (TN), pH, and Ca²⁺; and the fungal community structure was affected by pH, Mg²⁺, and K⁺. In conclusion, changes in soil environmental conditions by liming can affect soil microbial communities and functions through direct or indirect processes, further changing ecosystem processes.

In Korea, for heavy metal-contaminated soil, there are insufficient basic data as well as field application cases for soil washing. This study was conducted to suggest the significant factors and optimal operation conditions for the maximum heavy metal removal efficiency. Five types of washing solution [acid solution (HCl), citric acid, oxalic acid, EDTA, and CaCl₂], washing time (10–360 min), and solid-solution ratio (1:2–1:100) were selected as significant operational factors. Non-observed effect concentration (NOEC) and central composite rotatable design (CCRD) were applied to derive the optimal conditions. The soil pH was slightly alkali, and it was highly contaminated by Cd (17.34 mg kg⁻¹), Cu (307.76 mg kg⁻¹), Pb (714.78 mg kg⁻¹), and Zn (1755.47 mg kg⁻¹), complexly. For all heavy metals, CaCl₂, a neutral salt, was difficult to achieve the remediation goal. On the other hand, Cd, Cu, and Pb were removed successfully from the soil by acid solution, citric acid, oxalic acid, and EDTA. For Zn, only acid solution and oxalic acid could meet the remediation goal (300 mg kg⁻¹). As the washing time increased, the heavy metal removal efficiency showed a tendency to increase overall. Especially, oxalic acid and acid solution were able to reach the highest efficiency point within 30 min, whereas citric acid and EDTA took 2 to 4 h at the longest. In the case of 1 M citric acid, through the CCRD experiment, optimal operation conditions (solid-solution ratio and washing time) could be deduced for each heavy metal. Furthermore, this series of processes can be utilized as a useful tool to find the optimal operating conditions and, at the same time, achieve the remediation goal.

Green buffer (GB) zones are designed to prevent the spread of air pollutants and odors from industrial complexes (ICs) to residential areas (RAs). We analyzed changes in the concentration of particulate matter (PM) and the number of high PM pollution days for 10 years after the GB was implemented, using the National Atmospheric Environmental Research Stations 2001–2018 dataset. We also performed field measurements of PM₁₀ and PM_2.5 from February 2018 to January 2019 to analyze the PM concentrations at human breathing height throughout the GB. Before GB implementation (2001–2006), PM₁₀ in the RA was 9% higher than that in the IC. After GB zone implementation (2013–2018), PM₁₀ in the RA was 11% lower than that of the IC. Furthermore, the PM concentration in the RA (slope = ∆Concentration/∆Time, −2.09) rapidly decreased compared to that in the IC (slope = −1.02) and the western coastal area (WCA) (slope = −1.55) over the 10-year period. At PM concentrations at human breathing height, PM₁₀ and PM_2.5 in the RA were lower than those in the IC by 27% and 26%, respectively. After GB implementation, the wind speed was positively correlated but SOx was negatively correlated with the PM reduction rate at a local scale. These results show that there was a reduction of PM during and after GB implementation, implying the need for proper management of GBs and continuous measure of pollutant sources at the green buffers of industrial complexes.

Ammonia (NH₃) is an important precursor for particulate secondary aerosol formation. This study was conducted to evaluate the applicability of a passive sampler (PAS) for estimating the NH₃ emission from chemical fertilizer application (85 kg-N·ha⁻¹) at field scale and to compare the results with a chamber system for the calculation of NH₃ emission flux at lab scale. The application of chemical fertilizer increased the ambient NH₃ concentration from 7.11 to 16.87 μg·m⁻³. Also, the ambient NH₃ concentration measured by the PAS was found to be highly influenced by not only the chemical fertilizer application but also the weather (temperature and rainfall). Wind rose diagram data can be useful for understanding the distribution of ambient NH₃ concentration. In the case of a chamber with few environmental variables, NH₃ was emitted very quickly in the early stages and gradually decreased, whereas it was delayed at intervals of about one week at the site. It was found that daily temperature range, atmospheric disturbance by wind and rainfall, changes in soil moisture, and the presence of a flooded water table were the main influencing factors. The PAS data and the chamber system data were observed to have significant differences in spatial-temporal scale. In order to reduce the gap, it seems to be necessary to further develop a chamber system, in order to improve the precision of field analysis and to strengthen the connection between experimental results.

To identify the reference ecosystem conditions of a damaged forest, we developed a community development scenario using a syntaxonomic approach. To facilitate this choice, we sought to provide a framework based on ecological theory, specifically on the relationship between vegetation and environmental properties. We identified forest composition species in 216 sample plots from Mt. Gariwang, a representative temperate deciduous forest in South Korea, and divided them into 13 species groups, including the Quercus mongolica Fisch.-Fraxinus rhynchophylla Hance community and eight vegetation types. In addition, nine major environmental properties that explain community composition, including elevation, were identified through multivariate analysis. A physiognomy map enabled the identification that the area must be large and the habitat must be continuous to help determine the reference ecosystem. In conclusion, plant–environmental interaction analysis is a valuable tool for identifying reference communities or source locations for seed migration in relation to various habitats. These reference ecosystems provide insights into the restoration of damaged areas and an overview of important considerations for restoring the relationships between biodiversity and ecosystem function.

Using a fumigation sterilizer (Dazomet) for nematode control, this study determined the effect of soil sterilization on the quantity and quality of the growth of Pinus densiflora Siebold & Zucc. and Larix kaempferi (Lamb.) Carrière seedlings in an open-field nursery at Jeongseon-gun, Kangwon-do, Republic of Korea. Most soil nematodes disappeared after fumigant sterilization. The organic matter content, cation exchange capacity, and Mg²⁺ content of the soil increased significantly, but the electrical conductivity (EC) decreased. The quantity of pine and larch seedlings was highly correlated with the soil nematode density. The soil properties changed due to soil fumigation, which affected the growth of both species. Pine seedling growth was affected by the soil chemical properties, such as available phosphorus (AP), Ca²⁺, Mg²⁺, and EC, and the growth of larch seedlings was affected by the EC and nematode density. The quality of the pine seedlings improved, whereas that of larch did not. This was a result of the difference in their tolerance to soil salinity. The seedling quality index (SQI) of the two species was related to the EC, but the pine seedlings were more affected by the EC, indicating that the control of soil nematodes by fumigant treatment significantly increased the quantity of seedlings produced and partly improved their quality. Soil management using a fumigant treatment was more efficient for producing pine seedlings than larch. Our results can be used to improve agricultural and forestry economics.