For the ammonia generated in Korea, the contribution rate of livestock manure is high, and a large amount of ammonia (NH₃) is emitted into the atmosphere during the soil application process. Volatilization of NH₃ is affected by soil characteristics as well as manure characteristics, but the current inventory does not sufficiently reflect this. This study was conducted to confirm the change of the NH₃ emitted from liquid fertilizer (LF) due to soil pH and to evaluate the impacts of biochar (BC) on the suppression of NH₃ volatilization. Estimating the NH₃ emission flux using the chamber for 24 soils after LF treatment, it showed a tendency to increase exponentially as the pH in soil increased from 4 to 7. In addition, the parallel treatment of BC and LF increased the soil pH, thereby increasing the NH₃ emission flux. The rise of soil pH due to LF treatment is a temporary phenomenon that appears in the early stage, but since NH₃ volatilization is also highest at the beginning of LF application, the effect of soil characteristics on emission factor and its inventory should be considered when calculating the amount of NH₃ emissions. Therefore, follow-up studies such as subdividing and enhancing the NH₃ emission factor by soil characteristics and developing a reduction coefficient to certify the amount of emission reduction are needed.

Drought damage and waterlogging damage are the most frequent abiotic injuries throughout the lifespan of trees. Nonetheless, because the signs of visible damage are similar between these types of injury, physiological indicators must be analyzed to make a scientific differential diagnosis. This study was aimed at investigating growth and physiological indicators of drought (DS) and waterlogging stress (WL) in Prunus yedoensis. Overall growth indices such as tree height, diameter at root collar (DRC), and total dry weight could be ranked in the decreasing order “control > DS > WL.” In particular, there was a prominent decrease in root growth in WL, and DRC in DS was lower by 9.2% than DRC before the experiment. As for water saturation deficit (WSD) increased to 37.4% by 28 days after treatment initiation (DAT) in DS. WL showed a sharp decline of photosynthetic indicators such as the net photosynthesis rate (A), stomatal conductance (g_s), and maximum carboxylation rate (V_cmax) starting from 7 DAT. By contrast, DS manifested a significant decrease starting from 14 DAT. The DS had higher levels of leaf and root inorganic components than WL did, suggesting an improvement in the osmoregulatory ability. The overall nutritional status of WL was low due to deterioration of the absorption function of the roots. In both DS and WL, energy transfer rates of photochemical reactions, e.g. absorbed photon leads to reduction further than Q_A^- (Φ_PO), absorbed photon leads to electron transport further than Q_A^- (Φ_EO), and absorbed photon leads to reduction of Q_A^- (Ψ_O), decreased, as did vitality indices, e.g. the performance index on absorption basis (PI_abs), driving force on absorption basis (DF_abs), and the structure function index on absorption basis (SFI_abs). However, WL featured a decrease in Electron transport flux from Q_A to Q_B (ETo/RC) and Electron transport flux until PSI acceptors (REo/RC), whereas DS experienced a slight increase or almost no change. Consequently, PI_abs, DF_abs, SFI_abs, and the drought factor index are highly sensitive environmental-stress indicators, whereas WSD, DRC growth, chlorophyll a content, ETo/RC, and REo/RC appear to have high potential as diagnostic indicators of drought or waterlogging damage.

The Jeongseon Alpine Center, a degraded forestland, has a very unique soil feature as it was filled with soil cut from the nearby area and has not yet been rehabilitated since the end of the 2018 Winter Olympics. Therefore, this study attempted to identify a way to establish a stable and efficient planting groundwork to successfully restore this distinctive region. Six different planting groundworks, control, biochar, leaf-mold, mulching, tillage, and polyacrylamide treatments were constructed in September 2020. Soil-related indices have been tracked while the growth and physiological responses of planted Pinus densiflora (Pd) and Larix kaempferi (Lk) seedlings were monitored until May 2022. Mulching had 2–4 times the average SWC when compared to the control. Simultaneously, there was the least variation in soil temperature change, and total soil loss was only 0.05 ton/ha. Similarly, the leaf-mold had a relatively high SWC, and soil fertility increased, while total soil loss was 6.37 tons/ha, indicating a high trend in line with biochar. The Pd leaf-mold had the highest in A_max, E, g_s, and J_max. Furthermore, following the leaf-mold, mulching showed the second-highest photosynthetic indices in general, and the height and DRC also demonstrated favorable results in the above two treatments. Mulching had 1.6 to 2.2 times higher than the control group in PI_abs and PI_total, which represent photosynthetic vitality, so the impact on environmental stress was thought to be less than that of leaf-mold. The mulching of Lk showed the greatest growth and physiological responses, Nonetheless, the photosynthetic indices were rather low when compared to Pd, with no discernible differences across treatments. As a result, the considerable effect of the planting groundwork method could not be demonstrated. Therefore, in the case of Pd, the leaf-mold showed the best growth and physiological response. Nevertheless, in terms of soil temperature maintenance and soil loss for slope stability, mulching is assessed to be the most ideal planting groundwork method.

Trees in degraded forest areas are generally exposed to water stress due to harsh environmental conditions, threatening their survival. This study simulated the environmental conditions of a degraded forest area by constructing an artificial rainfall slope and observing the physiological responses of Pinus densiflora to control, mulching, and waterbag treatments. P. densiflora exhibited distinct isohydric plant characteristics of reducing net photosynthetic rate and stomatal transpiration rate through regulating stomatal conductance in response to decreased soil moisture, particularly in the control and waterbag treatments. Additionally, the trees increased photochemical quenching, such as Y(NPQ), to dissipate excess energy as heat and minimize damage to the photosynthetic apparatus. However, these adaptive mechanisms have temporal limitations, necessitating appropriate measures. Under extreme drought stress (DS45), mulching treatment showed 4.5 times and 2.2 times higher in PI_abs and SFI_abs than in the control, and after the recovery period (R30), waterbag and mulching treatment showed similar levels, while PI_abs and SFI_abs in the control were only 45% and 75% of those in the mulching and waterbag treatments, respectively. Specifically, mulching extended the physiological mechanisms supporting survival by more than a week, making it the most effective method for enhancing the planting ground in degraded forest areas. Although the waterbag treatment was less effective than mulching treatment, it still significantly contributed to forming better growth conditions compared to the control. These findings highlight the potential for mulching and waterbag treatments to enhance forest restoration efforts, suggesting future research and application could lead to more resilient reforested areas capable of withstanding climate change-induced drought conditions.

Forests are degraded from various factors, and the first step in restoration frequently involves revegetation. One of the degradations is wildfires, which damage vegetation, affect soils, and lead to the loss of ecosystem functions. Using seed mixtures is a viable method for restoring the ecosystems. This research investigated the impacts of six perennial plant seed mixtures derived from native plants in South Korea and the addition of two types of annual plant seeds to these mixtures, both separately and combined. Cultivation of the seed mixtures was conducted by pot cultivation in a greenhouse for the early stage of vegetation (16 weeks). The seed mixture treatment enhanced plant species diversity, number, and biomass. The seed mixture treatment elevated the urease activity from 14.42 to values between 33.88 and 55.74 μg NH₄-N g⁻¹ 2 h⁻¹. A seed mixture integrated with two annual plants heightened the phosphomonoesterase activity from 482.79 to 543.75 μg p-nitrophenol g⁻¹ h⁻¹. Nitrogen leaching was reduced across all seed mixture treatments, while phosphorus leaching diminished with the addition of the annual legume. These findings illustrate the influence of seed mixture treatments and the inclusion of annual seeds on the beginning stage of revegetation, offering a basis for further ecosystem restoration.

This study aimed to determine a method for restoring grasslands to forests in mountainous areas. The study was conducted in an area damaged by trampling due to construction activity and herding. Additionally, there were concerns of hindered tree growth due to the alpine region climate, characterized by the low temperatures, drying, and strong winds. Therefore, forest restoration treatments such as tillage, furrow, and shading were performed to improve growth conditions. From July 2021 to April 2023, soil temperature and moisture were monitored for each treatment plot, and changes in the initial growth and survival rate of Abies holophylla were investigated. Both soil temperature and soil moisture showed significantly higher values during the four seasons in the grassland-furrow treatment plot (p < 0.05). Compared to the grassland-control plot, the average soil temperature in winter was as high as 1.1℃, and the soil moisture in summer was as high as 20.3%. Additionally, the survival rate and relative growth rate were the largest in the grassland-furrow treatment plot. The survival rate was 87.5%, the relative growth rate in terms of height was 0.013, and the relative growth rate in terms of diameter at root collar was 0.023, indicating that furrow treatment had a positive effect on the initial survival and growth of seedlings. These results suggest that furrow treatment may be an appropriate restoration method when implementing forest restoration projects in areas where tree growth is challenged.