Search Results (15)

Abies koreana E.H.Wilson (Korean fir), an endangered high-altitude conifer native to South Korea, is facing severe population decline due to climate change and low germination rates. While ecological factors have been studied, the genetic and epigenetic mechanisms underlying its seed development are still poorly understood. DNA methylation, regulated by MET1 and CMT2, plays a critical role in the stability of gene expression during seed development. This study investigates the expression patterns of MET1 and CMT2 across 12 developmental stages, from pre-germination to post-germination, with a focus on shoot and root tissues. RNA-seq data were analyzed to identify MET1 and CMT2, and expression patterns were validated using RT-qPCR. MET1 showed high sequence conservation with conifers such as Pinus sylvestris, indicating potential conservation of CG methylation mechanisms among conifer species. CMT2 showed lower sequence conservation across species, indicating reduced evolutionary conservation compared to MET1. Tissue-specific analysis showed MET1 being predominantly active in shoots during cotyledon development, while CMT2 was upregulated in roots at later stages. These findings highlight the dynamic and tissue-specific roles of DNA methylation in the seed development of A. koreana, contributing to a better understanding of the genetic and epigenetic mechanisms involved in its germination and early growth. Full article

Increased drought frequency due to climate change is intensifying tree mortality, a critical issue in forest ecosystem management, especially in vulnerable subalpine ecosystems. Korean fir (Abies koreana E.H. Wilson), an endemic species of South Korea that grows in subalpine areas, is threatened by climate change-induced drought. However, our understanding of drought’s impact on tree mortality, particularly its seasonal and legacy effects, remains limited. To better understand drought-related mortality of Korean fir, we conducted annual mortality surveys, starting in 2012, at 10 fixed transects in Jirisan National Park, identified seasonal and legacy effects using redundancy analysis, and modeled Korean fir mortality, incorporating biotic and abiotic factors, using random forests. We found that early growing season drought had the greatest impact on Korean fir mortality, with legacy effects extending up to three years, while late growing season drought affected mortality only in the previous year. The mortality model achieved high predictive accuracy (94%) and revealed significant site- and size-dependent mortality patterns. These findings provide critical insights into the complex interactions between biotic and abiotic factors affecting tree mortality and offer valuable guidance for conservation strategies aimed at preserving climate-sensitive species in the face of ongoing climate change. Full article

Herein, we explored the ecologic niches of generalist and specialist species within the subalpine vegetation zone, a habitat of Abies sp. distributed throughout South Korea and China. We included Abies sp. habitats in inland areas of South Korea and parts of the Manchurian region of China. Rhododendron schlippenbachii Maxim., Acer pseudosieboldianum (Pax) Kom., Picea jezoensis (Siebold & Zucc.) Carrière, Betula ermanii Cham., Acer komarovii Pojark., Pinus koraiensis Siebold & Zucc., Betula davurica Pall., Betula costata Trautv., Quercus mongolica Fisch. ex Ledeb, and Sorbus commixta Hedl. were selected as generalist species. Betula chinensis Maxim., Betula platyphylla var. japonica (Miq.) H. Hara, Euonymus pauciflorus Maxim., Salix maximowiczii Kom., Cornus walteri F.T. Wangerin, Carpinus laxiflora (Siebold & Zucc.) Blume, Populus davidiana Dode, Philadelphus tenuifolius Rupr. & Maxim., Rhododendron brachycarpum D. Don ex G. Don, and Larix olgensis var. koreana (Nakai) Nakai were selected as specialist species. NMS ordination analysis showed that specialist, generalist, and other plant species distribution correlated with basal area at breast height, stand density, and species diversity index. Generalist species could be grouped based on Quercus sp., Betula sp., and Acer sp. niche spaces. Specialist species shared ecological niches with plant species found in the limestone zone, sedimentary rock zone, and valley area. Full article

The Korean fir tree Abies koreana, an endangered species in Korea, faces threats primarily from climate change-induced stress and drought. This study proposed a sustainable method to enhance A. koreana drought tolerance using a black yeast-like fungus identified as Aureobasidium pullulans (AK10). The 16S/ITS metabarcoding analysis assessed the impact of drought and AK10 treatment on the seedlings’ rhizosphere microbiome. Results revealed a profound drought influence on the microbiome, particularly affecting fungal mycobiota. Drought-stressed seedlings exhibited elevated Agaricaceae levels, opportunistic fungi generally associated with decomposition. AK10 treatment significantly mitigated this proliferation and increased the relative abundance of beneficial fungi like Cystofilobasidium and Mortierella, known biocontrol agents and phosphate solubilizers. A notable reduction in the phytopathogenic Fusarium levels was observed with AK10, alongside an increase in beneficial bacteria, including Azospirillum and Nitrospirillum. Furthermore, the conducted correlation analysis shed light on microbial interrelationships within the rhizosphere, elucidating potential co-associations and antagonisms. Taken together, the isolated A. pullulans AK10 identified in this study serves as a potential biostimulant, enhancing the drought tolerance in A. koreana through beneficial alterations in the rhizosphere microbiome. This approach presents a promising strategy for the conservation of this endangered species. Full article

Severe declines in the population of Abies koreana, a conifer native to the subalpine regions of South Korea, are likely a consequence of climate change. However, local-scale modeling of the species’ spatial distribution has seen limited application to in situ conservation policies. Therefore, we intended for this study to examine the applicability of fine-scale species distribution modeling of A. koreana in the Mt. Jiri National Park area in S. Korea in order to explore candidate areas for its in situ conservation. We simulated the potential habitat of the species in the area with four separate models using different dominance patterns, then created an index based on habitability probabilities and residual durations to determine priority conservation areas. Under the highest sensitivity of potential habitats to temperature (spatially downscaled based on geomorphological characteristics), rapid habitat reduction occurred under climate warming in all experiments. At the regional scale, hydrological characteristics such as precipitation and slope characterized different secondary habitat distributional patterns among the experiments. Final conservation priority sites were identified based on specified criteria for the designed index. Our results suggest that a fine-scale modeling system with adequate spatial resolution of environmental inputs is advantageous in representing local habitat characteristics of A. koreana and can be applied to in situ conservation strategies. Full article

Plant endophyte and epiphyte communities cooperatively interact with their host plants and play crucial roles in sustaining plant fitness. In Korea, a variety of studies have been conducted to elucidate the reasons for the declining population of the endangered Korean fir (Abies koreana), but the relationship between microbiota and the healthy condition of trees remains unclear. Here, we conducted bacterial 16S rRNA gene and fungal ITS sequence analyses to dissect the composition of endophytic and epiphytic microbiota in both live and dead trees located in the same Mt. Jiri habitat. In the live trees, the bacterial class Armatimonadia and the lichenized fungi groups were significantly dominant, whereas many bacterial and fungal taxa mainly found in rotten wood were enriched in the dead trees. Functional prediction of the microbial communities in live trees suggested the possibility that bacterial endophytes and epiphytes play a role in inorganic nutrient metabolism and fungal endophytes and epiphytes produce biologically active secondary metabolites, thereby contributing to the healthy condition of Korean fir trees. The ecological function of endophytes and epiphytes in dead trees was predicted to be involved in the decomposition of wood for nutrient recycling. Our analyses revealed a distinct difference in microbial communities depending on the health condition of Korean fir trees. The results from this study would be useful for understanding the ecological function of endophytic and epiphytic microorganisms to conserve and manage this endangered species from ecologically vulnerable environments. Full article

Knowledge of forest recovery processes after severe disturbances, such as tropical cyclones, is essential for understanding the mechanisms maintaining forest diversity and ecosystem functioning. However, studies examining the impact of tropical cyclones on forest dynamics are still rare, especially in Northeast Asia. Here, we explore the complex responses of vegetation and soil chemistry to severe tropical cyclone disturbances in Hallasan National Park in South Korea. Vegetation and soil were examined five years before and five years after passages of tropical cyclones in 2012 in natural broadleaf and coniferous forests along an elevation gradient from 950 to 1770 m a.s.l., including the largest population of endemic Abies koreana. Tropical cyclones caused abundant tree mortality, resulting in a 46% decrease in stem basal area. Tropical cyclone disturbances triggered the spread of pioneer trees and shrubs and intense clonal propagation of graminoids, including dwarf bamboo, resulting in less diverse understory vegetation, especially in coniferous forests. In contrast, broadleaf forests at lower elevations experienced only minor disturbance. Opening of canopies after tropical cyclone disturbance led to the decrease in soil cations and doubling of available soil phosphorus stock, which likely contributed to the increased coverage of clonal graminoids, especially in coniferous forests (from 36 to 66%). Hence, increased competition of graminoids and reduction in seed fall and seedling recruitment prevented A. koreana regeneration. The subalpine forest dominated by A. koreana is forecasted to gradual loss due to the fact of temperature increases, intensified tropical cyclones and, particularly, due to the altered competition between dwarf bamboo and fir seedlings. Full article

The Korean fir (Abies koreana), a native coniferous tree species mainly found on Mt. Halla in Jeju, South Korea, is suffering from continuous population decline and has been declared an endangered species. Research efforts have focused on the possible abiotic causes behind this worrying decline. However, the potential link between tree vitality and the rhizosphere microbiome remains unclear. In this study, a comparative metagenomic 16S rRNA sequence analysis was used to investigate the composition of the rhizosphere microbiota of samples collected from healthy and die-back-affected trees on Mt. Halla. The results indicated a significant reduction in the richness and diversity of microbiota in the rhizosphere of die-back-affected trees. Moreover, the relative abundance of Proteobacteria, Actinobacteria, and Bacteroidetes were significantly higher in healthy trees than in standing dead trees. Many bacterial genera were significantly more abundant in the rhizosphere of healthy trees, including those known for promoting plant growth and tolerance to biotic and abiotic stresses (e.g., Bradyrhizobium, Rhizomicrobium, Caulobacter, Nitrosospira, Rhizobacter, Paraburkholderia, Rhizobium, Devosia, Caballeronia, Niveispirillum, Dyella, Herbaspirillum, Frankia, Streptomyces, Actinoallomurus, Lysobacter, Luteibacter, Mucilaginibacter, and Variovorax). To our knowledge, this is the first report on rhizosphere bacterial microbiome dysbiosis in die-back-affected Korean fir trees, suggesting that the influence of rhizosphere microbiota should be considered to save this endangered species by investigating possible intervention strategies in future work. Full article

Projected changes in temperature and precipitation in mid-latitude wet regions are expected to significantly affect forest ecosystems. We studied the physiological and shoot growth responses of Abies holophylla and Abies koreana seedlings to warming (3 °C above ambient temperature) and increased precipitation (irrigation with 40% of rainfall) treatments under open-field conditions. The physiological parameters, quantified by the net photosynthetic rate, transpiration rate, stomatal conductance, and total chlorophyll content, were monitored from July to October 2018. Shoot growth (i.e., root collar diameter and height) was assessed in August and December 2018. Irrespective of the treatments, the physiological parameters of both species decreased from July to August under warming treatment due to heat stress before recovering in September and October. Warming alone (W) and warming along with increased precipitation (W*P) decreased the physiological activities of both species in July, August, and September, with more pronounced effects on A. koreana compared with A. holophylla. Increased precipitation resulted in the increased chlorophyll content of both species in October. Shoot growth was not generally affected by the treatments, except for a subtle reduction in height under W*P for A. koreana. A. holophylla had consistently higher values for the physiological parameters and shoot growth than A. koreana. Our results indicate that the physiological activities of the Abies species could be seriously reduced under climate change, with a more severe impact on A. koreana. Among the two species, A. holophylla appears to be a more robust candidate for future forest planting. Full article

The restoration of damaged or disrupted forests with genetically appropriate restoration planting material that can adapt to future environmental conditions will ensure the conservation of forest genetic resources. Abies koreana is endemic to the Republic of Korea, with declining populations under current environmental changes. In this study, we examined the genetic diversity of its largest population growing on Mt. Hallasan to determine the sampling size of planting material from the population that will ensure 95% coverage of alleles in the population. We evaluated the genetic diversity and spatial genetic structure of three subpopulations of A. koreana on Mt. Hallasan. A total of 456 samples were evaluated using 10 microsatellites. The observed heterozygosity and expected heterozygosity were 0.538 and 0.614 at the population level, respectively. The differences among the subpopulations accounted for 4% of the total variance. Intervals between individuals of the sample to be extracted were based on the two-target distance (5 and 10 m) inferred from the spatial genetic structure. Through random sampling methods considering the target distance, we showed that genetic diversity can be captured by obtaining at least 35 individuals in the population of A. koreana on Mt. Hallasan. Full article

Korean fir (Abies koreana E.H. Wilson) is a unique Pinaceae tree species endemic in Korea. In recent years, it is believed that climate change has caused many of them to die. Therefore, it has become extremely important to protect and preserve this tree species. In this study, the possibility of callus induction using different explants, media, and plant growth regulators (PGRs) was studied. After the dormancy period in May 2020, needles and stem segments that grew from the leaf buds as the explants were collected from one-year-old shoots. The explants were disinfected and subsequently transferred to culture media supplemented with different combinations of auxins and cytokinins. These explants were cultured in the dark in a culture room with a 16 h photoperiod, day/night temperature of 24/18 °C, and 80% relative humidity. After 8 weeks, significant differences were observed in the callus induction and proliferation, as affected by the explant type, basic medium, and PGR. The stem segments were more suitable as the explants for callus induction than needles were. Furthermore, fluffy calli suitable for differentiating the regeneration buds were observed on the calli induced from stem segments. The Murashige and Skoog (MS) medium was the most effective of the three media used in this study, namely MS, Douglas fir cotyledon revised (DCR), and Quoirin and Lepoivre (LP) media, with the highest callus induction ratio of stem segments being 100.0%. The highest fresh callus weight was also observed on the MS medium (819.3 mg). Moreover, the PGR combinations of α-naphthaleneacetic acid (NAA), 2,4-dichlorophenoxyacetic acid (2,4-D), and 6-benzylaminopurine (6-BA) consistently exerted a positive influence on callus induction throughout this study. In addition, the advantages of these two kinds of PGR were reflected in callus proliferation. The callus proliferation ratio reached 1147.6% as compared to the initial fresh weight, with a high concentration of 2,4-D (3.0 mg·L⁻¹). In conclusion, the MS medium was optimal for callus induction on the stem segment explants, and 2,4-D promoted callus induction as well as an increased proliferation ratio of callus in A. koreana. Full article

The purpose of this study was to investigate the role of strong winds and aging in the death and/or decline in the growth of Korean fir on Mt. Halla in Korea. Bangeoreum (BA-S), Jindalrebat (JD-E), and Youngsil (YS-W) on the southern, eastern, and western slopes of Mt. Halla (ca. 1600 and 1700 m a.s.l.) were selected for the study. The site chronologies were established using more than 10 living Korean firs at each site. Additionally, to date the years and seasons of death of standing/fallen dead Korean firs, 15/15, 14/15, and 10/10 trees were selected at BA-S, JD-E, and YS-W, respectively. After adjusting the age with the period of growth up to the sampling point, the oldest Korean fir found among the living trees was 114 years old at JD-E and the oldest fir among the dead trees was 131 years old at JD-E. Besides this, most of the trees at BA-S and JD-E were found to have died between 2008 and 2015, and at irregular intervals between 1976 and 2013 at YS-W. Also, the maximum number of trees, that is, 62.7% died between spring and summer, followed by 20.9% between summer and autumn, and 16.4% between autumn of the current year and spring of the following year. Abrupt growth reductions occurred at BA-S and JD-E, and have become more significant in recent years, whereas at YS-W, the abrupt growth reduction and recovery occur in a cyclic order. The intensity and frequency of the typhoons increased from 2012, and this trend was in-line with the increased number of abrupt growth reductions at BA-S and JD-E. Therefore, the typhoons of 2012 are considered as the most likely influencing factor in death and/or growth reduction in Korean firs. In contrast, the decline in the growth of the Korean firs located on the windward slope (YS-W) showed a relationship with winds stronger than 25–33 m/s. Full article

Climate change is recognized as a major threat to global biodiversity and has already caused extensive regional extinction. In particular danger are the plant habitats in subalpine zones, which are more vulnerable to climate change. Evergreen coniferous trees in South Korean subalpine zones are currently designated as a species that need special care given their conservation value, but the reason for their decline and its seriousness remains unclear. This research estimates the potential land suitability (LS) of the subalpine zones in South Korea for six coniferous species vulnerable to climate change in the current time (1970–2000) and two future periods, the 2050s (2041–2060) and the 2070s (2061–2080). We analyze the ensemble-averaged loss of currently suitable habitats in the future, using nine species distribution models (SDMs). Korean arborvitae (Thuja koraiensis) and Khingan fir (Abies nephrolepis) are two species expected to experience significant habitat losses in 2050 (−59.5% under Representative Concentration Pathway (RCP) 4.5 to −65.9% under RCP 8.5 and −56.3% under RCP 4.5 to −57.7% under RCP 8.5, respectively). High extinction risks are estimated for these species, due to the difficulty of finding other suitable habitats with high LS. The current habitat of Korean fir (Abies koreana), listed as a threatened species on the International Union for Conservation of Nature (IUCN) Red List, is expected to decrease by −23.9% (RCP 4.5) to −28.4% (RCP 8.5) and −36.5% (RCP 4.5) to −36.7% (RCP 8.5) in the 2050s and 2070s, respectively. Still, its suitable habitats are also estimated to expand geographically toward the northern part of the Baekdudaegan mountain range. In the context of forest management and adaptation planning, the multi-model ensemble approach to mapping future shifts in the range of subalpine tree species under climate change provides robust information about the potential distribution of threatened and endanger Full article

Research Highlights: Technology advances have allowed for a new approach to research the decline of the Korean fir (Abies koreana E.H.Wilson). This study provides insights into the exact causes leading to this decline. Background and Objectives: Various factors could lead to the decline of fir trees around Mt. Halla, Korea, but these have not yet been verified. Here, the Korean fir across Mt. Halla were classified as dead or living and mapped using high-resolution orthorectified aerial images and three-dimensional (3D) stereoplotting. Materials and Methods: Aerial photographs were used to map spatial distribution and analyze the distribution patterns and mortality of the Korean fir. The electronic stereoplotting program (Geo3Di-PRO) enabled the creation of 3D images from aerial photographs. General, altitudinal, and topographical distribution was assessed. Results: Their accumulated percent mortality rate (APMR) showed positive correlations with altitude and tree density, a negative correlation with terrain slope, and no consistent correlation with solar radiation. The results indicate that increases in the density of Korean firs are related to decreased growth in areas at high altitude, on gentle slopes, and with high solar radiation. Consistent positive correlations between density and APMR indicate that fir mortality can be attributed to environmental deterioration and the establishment of unfavorable growth conditions. Areas with high APMR and density had gentle slopes, thus high soil moisture, or relatively high annual precipitation owing to high altitude. Conclusion: Fir mortality on Mt. Halla can be attributed to long-term persistently high rainfall and subsequent excess soil moisture. Full article

A regional decline in the Korean fir (Abies koreana) has been observed since the 1980s in the subalpine region. To explain this decline, it is important to investigate the degree to which environmental factors have contributed to plant distributions on diverse spatial scales. We applied a hierarchical regression model to determine quantitatively the relationship between the abundance of Korean fir (seedlings) and diverse environmental factors across two different ecological scales. We measured Korean fir density and the occurrence of its seedlings in 102 (84) plots nested at five sites and collected a range of environmental factors at the same plots. Our model included hierarchical explanatory variables at both site-level (weather conditions) and plot-level (micro-topographic factors, soil properties, and competing species). The occurrence of Korean fir seedlings was positively associated with moss cover and rock cover but negatively related to dwarf bamboo cover. At the site level, winter precipitation was significantly and positively related to the occurrence of seedlings. A hierarchical Poisson regression model revealed that Korean fir density was negatively associated with slope aspect, topographic position index, Quercus mongolica cover, and mean summer temperature. Our results suggest that rising temperature, drought, and competition with other species are factors that impede the survival of the Korean fir. We can predict that the population of Korean fir will continue to decline in the subalpine, and only a few Korean fir will survive on northern slopes or valleys due to climate change. Full article