Search Results (19)

Pine wilt disease, caused by the pinewood nematode, affects Pinus densiflora, P. koraiensis Siebold and Zucc., and P. thunbergii Parl. in South Korea. It is primarily spread by vectors such as Monochamus alternatus Hope and M. saltuarius (Gebler). However, biological control research in this context remains limited in South Korea. We identified 15 parasitoids of these vectors, namely, two ectoparasitic larval parasitoids, Cyanopterus flavator (Fabricius) and Spathius verustus Chao, both in Braconidae, Hymenoptera. A field survey was conducted in Pohang from 2018 to 2020 to elucidate the ecological and biological characteristics of these parasitoids. The average parasitism rates of C. flavator were 6.3% and 1.0%, whereas those of S. verustus were 0.7% and 0.5% on M. alternatus and M. saltuarius, respectively. Both C. flavator and S. verustus appeared to prefer M. alternatus to M. saltuarius, but a statistically significant difference was observed only for C. flavator (p < 0.001). The peak season and tree height with the highest parasitism rate of C. flavator coincided with the period when M. alternatus larvae lived beneath the bark and the highest larval density of M. alternatus and M. saltuarius occurred in pine trees. These findings provide valuable information for determining the optimal release time and height for C. flavator to achieve effective biological control. Full article

Forests play a crucial role in South Korea’s carbon neutrality goal and require sustainable management strategies to overcome age-class imbalances. The Generic Carbon Budget Model (GCBM) offers a spatially explicit approach to simulate carbon dynamics at a regional scale. In this study, we utilized the GCBM to analyze the carbon budget of forests in South Korea and produce spatiotemporal maps for distribution of the forest biomass. The growth parameters of five representative tree species (Pinus densiflora Siebold & Zucc., Larix kaempferi Carr., Pinus koraiensis Siebold & Zucc., Quercus mongolica Fisch. ex Ledeb., Quercus variabilis Blume), which are the main species in South Korea, were used to operate the model. In addition, spatial data for harvest and thinning management activities were used to analyze the effects of anthropogenic activities. In 2020, the aboveground and belowground biomass were 112.98 and 22.84 tC ha⁻¹, and the net primary productivity was 8.30 tC ha⁻¹ year⁻¹. These results were verified using comparison with statistics, a literature review, and MODIS NPP. In particular, broadleaf is higher than conifer forest in net primary production. The Canadian GCBM with Korean forest inventory data and yield curves successfully estimated the aboveground and belowground biomass of forests in South Korea. Our study demonstrates that these estimates can be mapped in detail, thereby supporting decision-makers and stakeholders in analyzing the carbon budget of the forests in South Korea and developing novel schemes that can serve regional and national aims related to forest management, wood utilization, and ecological preservation. Further studies are needed to improve the initialization of dead organic matter pools, given the large-scale afforestation efforts in recent decades that have established South Korea’s forests on predominantly non-forest sites. Full article

To effectively combat climate change and put plans in place to enhance the health and quality of forests, research on the connections between long-term climate change and tree ring width is essential. Here, Pinus densiflora Siebold & Zucc. and Robinia pseudoacacia L. in the Mount Tai area were studied. Specifically, their tree ring width characteristics were investigated according to the principles of dendrochronology, based on the analysis of multiyear climate data (1972–2022). The results showed that (1) the variation in tree ring width of Pinus densiflora Siebold & Zucc. generally decreased. Its basal area increment sequence presented a “growth-decline” change process. The trend for Robinia pseudoacacia L. was stability at first and then a reduction. Its basal area increment sequence presented a “growth-stabilization” change process. (2) The standard chronologies of both tree species contained more environmental information than the residual chronologies, rendering the former more appropriate for analysis. (3) The tree ring width of Pinus densiflora Siebold & Zucc. was positively correlated with the mean maximum temperature in February, March, and July, the mean temperature in May, and the mean precipitation in December of the previous year and June of the current year. The tree ring width of Robinia pseudoacacia L. was positively correlated with the mean and maximum temperatures in October of the previous year, the mean maximum temperature in May of the current year, and the mean temperature in July of the current year. This variable was positively correlated with the mean precipitation in November of the previous year and July of the current year but negatively correlated with the mean minimum temperature in November of the previous year and the mean temperature in December of the current year. (4) During 1987–1988, 1994–1995, 2005–2006, and 2018–2019, the tree ring width was restricted by rising temperatures and low precipitation, with variations in tree ring width observed in various hydrological periods. (5) The moisture index, followed by the warmth index, precipitation and temperature, was the primary climate factor determining the tree ring width in both tree species. Full article

Subterranean termites of the species Reticulitermes speratus kyushuensis Morimoto (Isoptera: Rhinotermitidae) are notoriously destructive soil-dwelling pests that feed on the cellulosic wood biomass. This leads to tremendous losses of forest trees such as Pinus densiflora Siebold and Zucc. (Pinales: Pinaceae) and precious wooden structures of cultural heritage. This study investigated the efficacy of chitinase and protease produced by Bacillus licheniformis PR2 as cuticle-degrading enzymes for the biocontrol of worker termites. Bacillus licheniformis PR2 produced a strong chitinase and protease activity up to a maximum of 82.3 unit/mL and 35.9 unit/mL, respectively, and caused a lethal effect on termites under laboratory conditions. Treatment of termites with the bacterial broth culture and the crude enzyme fraction of B. licheniformis PR2 resulted in a maximum mortality rate (with a median lethal time (ET50)) of 83.3% (3 h, 36 min) and 88.9% (2 h, 59 min), respectively. The termites treated with B. licheniformis PR2 exhibited loss of setae, disintegration of epicuticle, rupturing of procuticle, and swelling at sockets. The degradation of cuticular chitin and glycoprotein polymers in the termite cuticle by chitinase and protease enzymes produced by B. licheniformis PR2 represents an effective eco-friendly strategy for controlling termite damage in Korean cultural heritage sites and forests. Full article

Overwintering and spring recovery of pine needles have important ecological significance. The natural changes in physiological state, photosynthetic function, and material metabolism in needles of Pinus densiflora Siebold & Zucc. from the autumn of 2020 to the spring of 2021 were assessed. The photosynthetic rate (Pn) of P. densiflora needles decreased first and then increased, with the maximum Pn observed in the autumn. After experiencing sub-zero temperatures in the winter, needles of P. densiflora still performed weak photosynthesis at a temperature above zero. In the spring, the Pn gradually recovered but could not recover to the maximum. Under sub-zero temperatures in the winter of 2020, the plasma membrane permeability and MDA content of needles increased, whereas the chlorophyll content and Fv/Fm decreased significantly. The needles showed obvious characteristics of freezing injury. During the whole process, the water content of needles remained at a low level (about 60%), which gradually decreased with the increase of leaf age. The cell sap concentration and soluble sugar content of needles decreased with the decrease in air temperature and recovered in spring. Therefore, P. densiflora needles do not improve frost resistance through osmotic adjustment. However, the increasing carotenoid content is helpful for needles to tide over the winter. The soluble sugar and protein contents increased, implying they are important for the recovery of needles in spring. This study expands our understanding of the mechanism and ecological contribution of overwintering and spring recovery of pine needles. Full article

The study of population genetic structure and historical dynamics of species with disjunct distribution can reveal the mechanisms through with they were formed. Pinus densiflora is an essential tree species with ecological and economic value, and its natural distribution shows a disjunct pattern. Using transcriptome-level SNP data from 220 samples representing 32 naturally-distributed populations in East Asia, we investigated Pinus densiflora genetic diversity and structure, divergence time, and ancestral distribution. We identified five subpopulations which diverged approximately 2.02–1.49 million years ago, and found relatively low genetic differentiation among the three large subpopulations (SL, JH, and JK). Northeast China is the most likely origin, and its current distribution is the result of dispersal and vicariance events. It migrated southwest through the Liaodong Peninsula to the Shandong Peninsula and southeast through the Korean Peninsula to Japan. These results provide a basis for the conservation and management of P. densiflora in the future and the evolutionary study of species with similar life histories. Full article

The objectives of this study were to develop site index and variable-density yield models for Korean red pine (Pinus densiflora Siebold & Zucc.), Korean white pine (P. koraiensis S. & Z.), and Japanese larch (Larix kaempferi (Lamb.) Carrière) in Korea. The data were collected between 2012 and 2021 from repeatedly measured empirical plots in each target stand in the North Central region of Korea: Gangwon and North Gyeongsang provinces. To develop the site index for each species, a dominant height growth model by species was developed using the Chapman–Richards function. The site index was computed with a base age of 40 years and used as an independent variable to predict the stand volume. To develop the variable-density yield models, three stand density variables, the stand age, and the site index were applied. The stand density variables used were the stand basal area, the number of trees per hectare, and the relative density. All the models were successfully developed with significant parameters and reasonable fit statistics, and the residuals analyzed presented unbiased scatter plots. Yield models with the stand basal area, or the number of trees, can be used to predict the stand volume. The yield model with relative density was flexible to apply across the stand age because the input of the absolute stand density was not required. Model simulation and comparisons with other studies also supported the applicability of the models developed in this study. The models were found to be highly applicable for predicting and simulating these targeted stands, particularly in Korea. Full article

An ethanol extract (Pd-EE) of Pinus densiflora Siebold and Zucc was derived from the branches of pine trees. According to the Donguibogam, pine resin has the effects of lowering the fever, reducing pain, and killing worms. The purpose of this study is to investigate whether Pd-EE has anti-inflammatory effects. During in vitro trials, NO production, as well as changes in the mRNA levels of inflammation-related genes and the phosphorylation levels of related proteins, were confirmed in RAW264.7 cells activated with lipopolysaccharide depending on the presence or absence of Pd-EE treatment. The activities of transcription factors were checked in HEK293T cells transfected with adapter molecules in the inflammatory pathway. The anti-inflammatory efficacy of Pd-EE was also estimated in vivo with acute gastritis and acute lung injury models. LC-MS analysis was conducted to identify the components of Pd-EE. This extract reduced the production of NO and the mRNA expression levels of iNOS, COX-2, and IL-6 in RAW264.7 cells. In addition, protein expression levels of p50 and p65 and phosphorylation levels of FRA1 were decreased. In the luciferase assay, the activities of NF-κB and AP-1 were lowered. In acute gastritis and acute lung injury models, Pd-EE suppressed inflammation, resulting in alleviated damage. Full article

Pinus densiflora Siebold & Zucc. is a widely distributed conifer species in the Republic of Korea with economic and ecologic importance. However, P. densiflora is negatively influenced by various factors, such as forest fires, clearing of large numbers of trees infected with Pinus disease, and dieback. We aimed to use microsatellite markers to estimate the genetic diversity, differentiation, and structure of P. densiflora populations in the Republic of Korea. A total of 1844 samples from 60 populations were evaluated using 11 polymorphic microsatellite markers. The observed heterozygosity and expected heterozygosity were 0.652 and 0.673, respectively. The mean genetic differentiation among the populations was 0.013. Moreover, P. densiflora showed high genetic diversity and low genetic differentiation compared with conifer species, including Pinus species with similar life histories. Principal coordinates analysis and Bayesian clustering showed that P. densiflora has a weak geographical structure. The P. densiflora population at Mt. Halla, Jeju Island, showed the lowest genetic diversity and significant genetic differentiation compared with other mainland populations due to genetic drift and restricted gene flow. These findings can be useful for designing new conservation, management, and breeding strategies for P. densiflora populations in response to future environmental changes. Full article

Forest fires can have a direct and immediate impact on soil properties, particularly soil water repellency. This study investigated the direct impacts of the Gangneung forest fire of 2019 on soil properties and the spatial variability of soil water repellency with vegetation burn severity in the Korean red pine (Pinus densiflora Siebold and Zucc) forest of South Korea. A total of 36 soil samples were collected at depth intervals of 0–5 cm, 10–15 cm, and 20–25 cm from three burned sites, representing surface-fuel consumption (SC), foliage necrosis (FN), and crown-fuel consumption (CC), respectively. An unburned site was also used as a control. Soil properties such as soil texture, pH, bulk density, electrical conductivity (EC), total organic carbon (TOC), and cation exchange capacity (CEC) were analyzed in the laboratory. The increase in the sand fraction near the soil surface after a fire was associated with changes in silt and clay fractions. Moderate to high vegetation burn severity at the FN and CC sites caused a decrease in soil pH due to the thermal destruction of kaolinite mineral structure, but organic matter combustion on the soil surface increased soil pH at the SC site. Forest fires led to increases in total organic carbon at the FN and SC sites, owing to the external input of heat damaged foliage and burnt materials. Molarity of an ethanol droplet (MED) tests were also conducted to measure the presence and intensity of soil water repellency from different locations and soil depths. MED tests showed that vegetation burn severity was important for determining the strength of water repellency, because severely burned sites tended to have stronger water repellency of soil than slightly burned sites. Unburned soils had very hydrophilic characteristics across soil depths, but a considerably thick hydrophobic layer was found in severely burned sites. The soil water repellency tended to be stronger on steep (>30°) slopes than on gentle (<15°) slopes. Full article

Historical analogies can help us contextualize new technical developments with social, cultural, and political forces at work. The late Joseon Dynasty period of Korea (1639–1910), a closed economy with detailed written records, provides a rare opportunity to examine a social-ecological system (SES) responding to drivers of change over a long period of time. Based on historical records and reconstructed data, we aim to: (1) characterize how the expansion of human technology, Ondol (traditional underfloor heating system), affected different subsystems and their interactions within the SES over time, (2) examine the role of the government in promoting the technology and regulating its impacts, and (3) summarize the pertinent lessons learned from old Korea for governing a modern-day bioeconomy. Ondol allows various forest biomass to be utilized as household fuel, including fuelwood, forest litter, and grass scraped from forest floor. Continuous biomass harvesting over 250 years to feed Ondol contributed to forest degradation and the forest ecosystem condition trapped in the early successional stage in the Korean Peninsula. The ecological changes were exacerbated by the Pine Policy with a singular focus on reserving Korean red pine (Pinus densiflora Siebold and Zucc.) for government uses. The policy failed to recognize basic needs of the public while countenancing an expansion of Ondol and a cultural preference for heated floors that propagated an increased use of biomass fuel. This case illustrates the importance of recognizing potential technology traps where a human innovation opened opportunities for more resource use. The lessons learned from old Korea show that bioeconomy transitions would require multifaceted governance responses while being cautious about being too closely tied to the dominant national agenda. Environmental history has much to offer for understanding the social and ecological systemic risks of the current technical developments. We call for more historical analogs from different parts of the world to “move forward by looking back”. Full article

Tree-ring width (TRW) chronologies have successfully been used as climate proxies to infer climate variabilities over the past hundreds to thousands of years worldwide beyond observational records. However, these data are scarce over parts of subtropical East Asia, and especially over the Korean Peninsula. In this pilot study, Korean red pine (Pinus densiflora Siebold and Zucc.) TRW chronologies from Mt. Mudeung and Mt. Wolchul, South Korea, were developed, and their local- to large-scale climatic responses were investigated. Mt. Mudeung TRW had a positive association with local temperature in the preceding December and April. Mt. Wolchul TRW had a positive association with local temperature in the preceding December and most of the early summer to autumn months, and with local precipitation in February and October. On a large scale, both TRWs retained meaningful temperature and monsoon precipitation signals over East Asia and sea surface temperature signals over the Western North Pacific. The results suggest that the subtropical trees from South Korea can be used to infer past long-term climate variability at both local and large scales over East Asia and the Western North Pacific, such as the East Asian summer monsoon, the Kuroshio Current, the Western North Pacific Subtropical High, and El Niño–Southern Oscillation. Full article

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. Full article

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. Full article

The spectral response to arsenic (As) stress of pine needles (Pinus densiflora Siebold and Zucc.) from an abandoned lead (Pb)–zinc (Zn) mine was investigated based on chemical and spectroscopic analyses. The correlation analysis between the content of As in needle samples and that of soils and spectral parameters of the needle samples were conducted. The results showed very high correlation between As content in pine needles and soils. The major spectral response of pine needles to the As stress were characterized by the increase in the green and red color reflectance, the decrease in the first derivatives at 1648 nm, and the shrink in the red absorption feature. These changes were caused by the pigment content loss and the structural changes of phenolic compounds in the pine needles due to the As content. The linear regression analysis with the stepwise method showed the first derivatives at 668 nm and 1648 nm were the most useful variables in the regression model for As content prediction in pine needles. The As index of pine needles could be used to detect As content in soils associated with As and heavy metals contamination and/or mineralization in coniferous forests. Full article