Pinus Koraiensis Sieb Research Articles

Modeling knot geometry from scanned images of Korean pine plantations

Based on 1038 knots from 42 sample trees from 14 standard plots in Korean pine (Pinus koraiensis Sieb. et Zucc.) plantations in Heilongjiang Province, China, we developed a knot profile model system. The concepts of growth inflection point and death inflection point were proposed. Depending on the growth conditions near the growth inflection point of the knot, we divided the knots into two types: curved knots and linear knots. A logistic regression model was constructed to predict the shape of the knots. The area under the curve of the logistic regression model was 0.699 (95% confidence interval 0.661∼0.736), and the prediction accuracy was 0.69. Our research shows that for middle-aged and young forests, the relative radial distances of the growth inflection points at the upper edge and bottom edge of curved knots were larger than those in linear knots. The curved knots did not bend at the death inflection point, but linear knots may bend at the death inflection point. Models were constructed separately for curved knots and linear knots. The results showed that the application of the mixed-effects model significantly improves the model fitting effect.

The characteristics of the trees and seed’s viability of Korean pine (Pinus koraiensis Sieb. et Zucc.) at Verkhneussuriysky Forest Station

The characteristics of the trees and seed’s viability of Korean pine (Pinus koraiensis Sieb. et Zucc.) at Verkhneussuriysky Forest Station

Fungal Community Composition and Enzyme Activity in Different Type Bark of Pinus koraiensis

Pinus koraiensis Sieb. et Zucc. is an endemic and dominant tree in temperate zone needle broad-leaf mixed forest and has great economic and ecological value. As the barrier, pine bark has many important functions. However, the ecological functions and forming mechanism of bark fungal community are poorly understood. The aim of this study was to reveal the fungal community of Korean pine bark from Changbai Nature Reserve of Northeast China. Based on Illumina Hiseq2000 platform with five different types from three sites, the results showed that the bark types and collecting sites have strong influence on the fungal community structure. CCA demonstrates the physico-chemical properties of barks and sample collecting height are important factors. Spearman’s correlation coefficients between dominant ASVs and these factors showed the impact in detail. Dominant ASVs in living and dead tree bark are animal or plant pathogens mainly, and they are negative with the total N and P. Meanwhile, wood saprotroph and other undefined saprotroph fungi occur in the bark near the ground and they prefer the substrate with higher total N and P content. Furthermore, enzymes activities including lignin-related oxidoreductases, cellulose and hydrolytic enzyme are affected significantly by the bark’s physico-chemical properties.

Effects of canopy composition on snow depth and below-the-snow temperature regimes in the temperate secondary forest ecosystem, Northeast China

Seasonal snow cover provides a thermally stable and humid refuge for overwintering plants in temperate forests. Canopy composition changes snow processes and shapes the thermal regime. To explore canopy effects on snow depth (SD) and below-the-snow temperature, ultrasonic sensors and time-lapse infrared cameras were used to monitor SD over two winters. Three forest types with different canopy compositions [the ratio of Korean pine (Pinus koraiensis Sieb. et Zucc.) basal area, RKp] on adret (sunny) and ubac (shady) slopes, including broadleaved secondary forests, Korean pine-broadleaved mixed forests, and Korean pine plantations, were selected as sample sites. Results showed time-lapse cameras were more accurate for monitoring SD in studied forests. Increasing RKp increased the snow interception rate and reduced the peak SD, snow melting rate, and snow cover duration. 21–69% of the snowfall was intercepted by the forests, with the RKp explaining 89% of the variance in interception rates. All forest stands had the lowest interception rate for severe snow events. For each forest type, plots on ubac slopes had a lower interception rate and thicker snow cover due to the positive effects of prevailing northerly wind on snow accumulation. Inter-annual variation of snowfall affected SD, snow melting rate, and below-the-snow temperature, with smaller differences among forest stands during the below-normal snow winter (2018/2019). The subnivium established in all plots during the normal snow winter (2019/2020) with the longest maintenance in secondary forest on ubac slopes and the shortest maintenance in Korean pine forests. The temperature increment under snowpack was positively correlated with SD while negatively correlated with air temperature. Overall, the forest with fewer evergreen canopy compositions was covered with thicker snowpack for a longer duration and had a more stable and warmer temperature regime, and fewer freeze-thaw events beneath the snow, which were essential for safe overwintering of regenerated individuals.

Identification of Sex Pheromone Components of Korean Dioryctria abietella (Lepidoptera: Pyralidae) Population and Synergism of Pheromone and Pine Cone Volatile Blends.

(9Z,11E)-tetradecadienyl acetate (9Z,11E-14:OAc) and (3Z,6Z,9Z,12Z,15Z)-pentacosapentaene (C25 pentaene), known as the sex pheromone of the European Dioryctria abietella population, were identified in the Korean D. abietella population. The ratio of 9Z,11E-14:OAc to C25 pentaene extracted from female pheromone glands was 1:23. The electroantennogram (EAG) response of male antennae to 9Z,11E-14:OAc was stronger than to C25 pentaene, whereas an opposite EAG response was observed in female antennae. Major volatile compounds in mature Korean pine cone (Pinus koraiensis), such as limonene, myrcene, and (-)-α-pinene, elicited dose-dependent EAG responses of male and female antennae. In field attraction testing, traps baited with 100:1,000, 100:2,000, and 100:3,000 ug of 9Z,11E-14:OAc to C25 pentaene were the most attractive to male D. abietella. More males were attracted to traps baited with 9Z,11E-14:OAc+C25 pentaene+limonene than traps baited with 9Z,11E-14:OAc+C25 pentaene. This showed that limonene acted as a synergist to sex pheromone. Delta traps, wing traps, and diamond traps were superior to bucket traps for capturing D. abietella males. This study showed that pheromone traps baited with 100:1,000 ~ 100:3,000 ug of 9Z,11E-14:OAc to C25 pentaene and limonene will be useful for the exact monitoring of D. abietella flight phenology in Pinus koraiensis Sieb. & Zucc. (Pinales: Pinaceae) forests.

Direct in vitro organogenesis from sprouted seeds of a highly economical and ecological valued tree, Korean pine

Korean pine (Pinus koraiensis Sieb. et Zucc.) is a critical coniferous species ecologically. In addition, its fruits have numerous nutraceutical properties and its wood is high quality timber. However, this plant has a low propagation rate and is under risk of extinction. To accelerate breeding of the excellent seedlings and selection from Korean pine, determining methods to increase the number of Korean pine trees successfully is imperative. In this present study, using sprouted seeds as the initial explants, the de novo organogenesis system for this coniferous species has been successfully developed. After 30 days of incubation on Gupta and Durzan (DCR) medium containing 2 mg L−1 kinetin (KT) and 0.5 mg L−1 thidiazuron (TDZ), 92.67% of explants produced direct buds with an average of about 15 buds per explant. We confirmed the organogenic regeneration pattern by a scanning electron microscopy (SEM). For bud elongation after 60 days of culture, we obtained the highest mean length of 34.99 mm on DCR basal media supplemented with 6-benzyladenine (6-BA, 0.2 mg L−1), 1-naphthaleneacetic acid (NAA, 0.1 mg L−1), and activated charcoal (AC, 1 g L−1). The highest rooting rates of 20.74 and 21.48% were obtained within two months of culturing on 1/2 DCR medium (halved major elements) supplemented with 0.05 mg·L−1 NAA and 0.5 or 1 mg ·L−1 indole-3-butyric acid (IBA), respectively. Rooted shoots showed a survival rate of 90.28% after acclimatization in the substrate consisting of perlite, peat, and vermiculite (1:1:1). This protocol is a successful and efficient biotechnological approach to the micropropagation of Korean pine, and the results will be helpful to the clonal propagation and conservation of Korean pine.

Use of direct seeding and seedling planting to restore Korean pine (Pinus koraiensis Sieb. Et Zucc.) in secondary forests of Northeast China

The poor natural regeneration of Korean pine represents a substantial hurdle limiting the restoration of secondary forests to mixed broad-leaved Korean pine forests (MBKPFs). Active restoration based on direct seeding or planting seedlings is accordingly considered to be a prerequisite for promoting Korean pine recruitment in secondary forests. To evaluate the most effective practices for restoring Korean pine in secondary forests, we studied the effects of microsites associated with gaps of different sizes and within-gap locations on direct seeding (rodent access/exclusion and soil/litter cover) and seedling planting (1-, 2-, and 3-year-old seedlings). We found that an average of 82.4% of sown seeds were eaten by rodents, with only 9.9% germinating and surviving after two growing seasons. Among the germinated seedlings, 37.6% were subsequently excised by rodents, whereas 6% died due to other natural causes. Furthermore, compared with the control sites (forest understorey), we detected no significant differences among the different microsites with respect to an effective reduction in rodent damage or promotion of seed germination, whereas rodent exclusion was more effective in protecting seeds from predation than the effect of microsite. With regards to planted seedlings, we found that the proportion of survival and relative root collar diameter growth were highest in the center (64.1%) and edge (60.0%) sites of large gaps, and that the survival of planted seedlings (43.7%) was considerably higher than that of seedlings derived from directly sown seeds (9.9%). Collectively, our findings indicate that, owing to seed predation and seedling excision by rodents, direct seeding with either mesh or soil cover would not represent an effective strategy for promoting Korean pine recruitment in secondary forests. Accordingly, for the purposes of restoring secondary forests to MBKPFs, we recommend planting 3-year-old Korean pine seedlings in large gaps within secondary forests.

Effects of ontogenetic stage and leaf age on leaf functional traits and the relationships between traits in Pinus koraiensis

Investigating the effects of ontogenetic stage and leaf age on leaf traits is important for understanding the utilization and distribution of resources in the process of plant growth. However, few studies have been conducted to show how traits and trait-trait relationships change across a range of ontogenetic stage and leaf age for evergreen coniferous species. We divided 67 Pinus koraiensis Sieb. et Zucc. of various sizes (0.3–100 cm diameter at breast height, DBH) into four ontogenetic stages, i.e., young trees, middle-aged trees, mature trees and over-mature trees, and measured the leaf mass per area (LMA), leaf dry matter content (LDMC), and mass-based leaf nitrogen content (N) and phosphorus content (P) of each leaf age group for each sampled tree. One-way analysis of variance (ANOVA) was used to describe the variation in leaf traits by ontogenetic stage and leaf age. The standardized major axis method was used to explore the effects of ontogenetic stage and leaf age on trait-trait relationships. We found that LMA and LDMC increased significantly and N and P decreased significantly with increases in the ontogenetic stage and leaf age. Most trait-trait relationships were consistent with the leaf economic spectrum (LES) at a global scale. Among them, leaf N content and LDMC showed a significant negative correlation, leaf N and P contents showed a significant positive correlation, and the absolute value of the slopes of the trait-trait relationships showed a gradually increasing trend with an increasing ontogenetic stage. LMA and LDMC showed a significant positive correlation, and the slopes of the trait-trait relationships showed a gradually decreasing trend with leaf age. Additionally, there were no significant relationships between leaf N content and LMA in most groups, which is contrary to the expectation of the LES. Overall, in the early ontogenetic stages and leaf ages, the leaf traits tend to be related to a "low investment-quick returns" resource strategy. In contrast, in the late ontogenetic stages and leaf ages, they tend to be related to a "high investment-slow returns" resource strategy. Our results reflect the optimal allocation of resources in Pinus koraiensis according to its functional needs during tree and leaf ontogeny.

An attack of Ips amitinus (Coleoptera: Curculionidae: Scolytinae) on arboretum in West Siberia: New host of invasive bark beetle among exotic conifers

Abstract Invasive populations of small spruce bark beetle Ips amitinus were first registered in 2019 in the southeast of Western Siberia. In natural stands of Siberian pine (Pinus sibirica Du Tour), several hundred hectares of outbreak foci of the alien bark beetle were identified. In 2020, a local focus of the bark beetle was found in the conifer collection in the arboretum “Kedr” of the Institute of Monitoring Climatic and Ecological Systems SB RAS, 30 km from Tomsk. The bark beetle caused the main damage to the collection of pines. I. amitinus colonized both host plants Scotch pine (Pinus sylvestris L.) and mountain pine (Pinus mugo Turra), which were previously known to it in the native range in Europe, and the local Siberian species Siberian pine (Pinus sibirica Du Tour), Siberian spruce (Picea obovata Ledeb.) and introduced Far Eastern Korean pine (Pinus koraiensis Sieb. et Zucc.). Demographic characteristics of I. amitinus studied on damaged trees indicate its high reproduction potential in Siberia. The bark beetle outbreak focus was suppressed; however, this plantation requires further annual monitoring of pest abundance and distribution, both to preserve the scientific dendroecological field station and to study the implementation of sential plant conception in relation to the invasion of I. amitinus.

Soil mesofauna participating in driving home-field advantage differ between litter mass loss and nutrient release

Soil organisms play an important role in litter mass loss and nutrient release. Although soil mesofauna participating in driving home-field advantage (HFA) differ between litter mass loss and nutrient release, this has rarely been investigated. A reciprocal transplant experiment was conducted using litterbags with two sizes of mesh (0.01 mm and 1 mm) in Pinus koraiensis Sieb. & Zucc. and Larix olgensis Henry plantations. We found that P. koraiensis and L. olgensis litter had a significantly higher soil mesofaunal abundance at home habitat after 7 and 9 months, respectively. The P. koraiensis and L. olgensis litter were associated with a significantly higher abundance of Oribatida and Tomoceridae at home habitat after 7 and 9 months, respectively. Soil mesofauna enhanced the positive effect on HFA for litter mass loss and carbon release in P. koraiensis and L. olgensis litter that could be observed at months 7 and 9 of the experiment. Nevertheless, the soil mesofauna significantly contributed to the negative effect on HFA for nitrogen and sulphur release for both litter types after 12 months. Our findings suggest that soil mesofaunal specialization could promote HFA effect for litter mass loss and carbon release, but that their effect was only apparent during specific stages of litter decomposition. Soil mesofaunal specialization dynamics are correlated with microclimate conditions and litter quality. Soil mesofauna significantly contributed to the negative effect on HFA for nitrogen and sulphur release, due to the change in the litter quality and imbalance of soil mesofauna between the home and away from home habitats.

Regeneration and succession: A 50-year gap dynamic in temperate secondary forests, Northeast China

Forest gaps are essential small-scale disturbances in forest succession. However, little attention has been paid to the long-term effects of gap dynamics on woody species regeneration and succession. We selected 20 medium and 25 large gaps representing a range of age classes (0–10, 10–20, 20–30, 30–40, and 40–50 years) from remote-sensing images obtained in 1964, 1976, 1986, 1993, 2003, and 2014 to examine long-term gap regeneration processes in a secondary forest in Northeast China. We conducted field surveys to determine the regeneration status, density index (DI), and richness index (RI) of selected gaps. The importance value (IV) of each woody species was calculated, and all species were classified by shade tolerance. The results showed that in gaps of 0–10 years, the DI and RI were mainly dominated by shade-intolerant species in large gaps and intermediate species in medium gaps. When gap age increased to 10–20 years, the greatest RI was observed in large gaps due to an increase in intermediate species, and the dominant species (IV > 0.1) changed from shrubs to trees (Acer mono). The DI and RI decreased over time in medium gaps, but A. mono remained the dominant species in these gaps. By 20–30 years after gap formation, large gaps showed decreased DI and RI, associated with the exclusion of shade-intolerant and intermediate species, and Tilia amurensis joined the dominant species class. In medium gaps, a decrease in DI was associated with self-thinning among intermediate shade-tolerant species. Once gap age exceeded 30 years, the DI, RI, and dominant species became stable in both large and medium gaps. Our findings indicated that natural gaps can improve the regeneration of late-successional species in secondary forests, especially at the first 30 years. However, there was a barrier in succession of the secondary forests to climax forests relying on natural gap regeneration due to the absence of key species such as Korean pine (Pinus koraiensis Sieb. et Zucc.). These results can provide a significant reference for close-to-nature management of temperate secondary forests in practice.

Effects of Korean Pine Basal Area in Mixed Broadleaved–Korean Pine Forest Stands on Its Natural Regeneration in Northeast China

Abstract Understanding the natural regeneration of Korean pine (Pinus koraiensis Sieb. et Zucc.) in mixed broadleaved–Korean pine (MBK) forests is crucial for MBK forest conservation and secondary deciduous broadleaved forest restoration. We hypothesized the ratio of Korean pine basal area (RKp) in MBK stands affected its natural regeneration. Regeneration censuses, including the height, root collar diameter, age, and growth stages (younger seedling, older seedling, smaller sapling, and taller sapling) of Korean pine, were conducted in northeast China. Results indicated the stem density and age composition of younger seedlings were positively correlated with RKp, whereas those of the saplings were negatively correlated with RKp. In the stands with lower RKp (<80% in Lesser Khingan Mountains [LKM]; <40% in Lushuihe Forestry Bureau [LFB]), individuals in all growth stages regenerated well with an age span of 65 yr. However, the regeneration of taller saplings was severely inhibited with increasing RKp (LKM: RKp ≥ 80%; LFB: RKp ≥ 40%). In summary, RKp significantly affected the natural regeneration of Korean pine in MBK forests. The basal-area thresholds limiting regeneration were found to be 80% in LKM stands and 40% in LFB stands. These basal-area thresholds provided evidence of why the zonal climax was MBK forests rather than pure Korean pine forests.

Root Exudation Rates Decrease with Increasing Latitude in Some Tree Species

Research Highlights: Understanding of the spatial variation of root exudation on a regional scale can help understand the response of plant physiological activities to environmental changes. Background and Objectives: Although root exudation has become an important topic in belowground ecology, its relationship with root traits and environmental factors is poorly understood. Our objective was to explore how root traits and environmental factors influence root exudation. Materials and Methods: We used a multi-factorial design consisting of three tree species spanning across sites located at three latitudes to assess root exudation dynamics, which was measured using a syringe-basis incubation system. Results: The strongest and clearest effect observed in our study was a decrease in root exudation rates of Korean pine (Pinus koraiensis Sieb. et Zucc.) and larch (Larix gmelinii (Rupr.) Kuze.) at sites located in higher latitudes. Root exudation rates were positively related to mean annual temperature, mean annual precipitation, and negatively related to soil total organic carbon. Conclusions: Root exudation in coniferous species decreased at sites located in higher latitudes. Despite differences in root exudation rate among sites located at different latitudes and species with suitable variation in root morphological traits and environmental factors, we could not identify consistent influencing factors on root exudation rates.

Individual-tree diameter growth model for Korean pine plantations based on optimized interpolation of meteorological variables

To explore the influence of meteorological variables on the growth of Korean pine (Pinus koraiensis Sieb. et Zucc.) plantations and provide a scientific reference for the production and management of Korean pine, three approaches to interpolate meteorological variables during the growing season (i.e., May–September) were compared in Heilongjiang Province, China. Optimized meteorological variable interpolation results were then combined with stand and individual tree variables, based on data from 56 sample plots and 2886 sample trees from Korean pine plantations in two regions of the province to develop an individual-tree diameter growth model (Model I) and an individual-tree diameter growth model with meteorological variables (Model II) using a stepwise regression method. Moreover, an individual-tree diameter growth model with regional effects (Model III) was developed using dummy variables in the regression, and the significance of introducing these dummy variables was verified with an F-test statistical analysis. The models were validated using an independent data set, and the predictive performance of the three models was assessed via the adjusted coefficient of determination ( $${R}_{a}^{2}$$ ) and root mean square error (RMSE). The results suggest that the growth increment in tree diameter of Korean pine plantations was significantly correlated with the natural logarithm of initial diameter (ln D), stand basal area (BAS), logarithmic deformation of the stand density index (ln SDI), ratio of basal area of trees larger than the subject tree to their initial diameter at breast height (DBH) (BAL/D), and the maximum growing-season precipitation (Pgmax). The individual-tree diameter growth models of Korean pine plantations developed in this study will provide a good basis for estimating and predicting growth increments of Korean pine forests over larger areas.

Use of a combination of the MD simulations and NMR spectroscopy to determine the regulatory mechanism of pulsed electric field (PEF) targeting at C-terminal histidine of VNAVLH

In this study, the targeted regulatory mechanism of pulsed electric field (PEF) was explored for antioxidant activity improvement in four peptides, RGAVIH, RGAVLH, VNAVIH, and VNAVLH, of the pine nut (Pinus koraiensis Sieb. et Zucc). The VNAVLH peptide exhibited the best antioxidant activity and the β-sheet content decreased to a minimum value at 40 kV/cm. Moreover, the chemical shifts of hydrogen atoms of 2-H Asn and 6-H His shifted to a higher magnetic field. The connectivity between NαH (3.62 ppm) and CαH (8.10 ppm) of 6-His residue disappeared in PEF-treated peptide. Molecule dynamics (MD) simulation verified that the distances of Nα(H78)-Cα(H80) and H82-O94 increased, whereas –OH and –Cβ(H83) got closer in histidine residue after applying the electric field force. Therefore, the antioxidant activity enhancement of VNAVLH might due to the targeted regulation of PEF treatment on NαH-CαH and imidazole group in histidine.

The effect of granularity on surface roughness and contact angle in wood sanding process

Abstract Sanding is a common machining method to obtain good surface quality. The 2D surface roughness Ra presents high error due to the biological structure of wood materials. In this study, a new calibration method of reference plane is proposed to measure 3D surface roughness Sa, especially for large format panels. Besides, the effects of G (granularity) on Ra, Sa and θ (equilibrium contact angle) are investigated on Korean pine (Pinus koraiensis Sieb. Et Zucc.), JATOBA (Hymenaea cunrbaril L.) and medium density fiberboard (MDF) respectively. The experimental results show the standard deviations of Sa are much lower than that of Ra. As G increased, the variation of Ra, Sa and θ of Korean pine and JATOBA are distinct from MDF. The results of Grey Relevancy Degree (GRD) indicate MDF shows an obscure correlation between Sa and θ. The correlation between Sa and θ for Korean pine is the highest.

Selection of culture conditions for callus induction and proliferation by somatic embryogenesis of Pinus koraiensis

The induction and proliferation of embryogenic callus are key steps for large-scale propagation of somatic embryogenesis pathway and long-term preservation of coniferous germplasm. Callus can be induced from immature embryos of Korean pine (Pinus koraiensis Sieb. et Zucc.; Pinaceae) as explants, but there are problems, such as low proliferation efficiency, loss of embryogenicity, poor vigor; thus, best conditions for proliferation and culture of immature embryos of Korean pine are not yet clear. To solve the problems with somatic embryogenesis of Korean pine and determine the best culture conditions for callus induction and proliferation, we varied hormone concentration, subculture cycle of proliferation and other plant growth regulators combinations in media to induce callus formation by megagametophytes of three Korean pine families at different developmental stages, then analyzed the effects on embryogenic callus retention and cell proliferation using a quadratic regression orthogonal rotation design. The results showed that the family origin and collection date of explants significantly affected callus induction (induction rate reached 1.67%). Embryogenic maintenance and callus proliferation were best on DCR medium supplemented with 0.25 mg L−1 6-benzyl adenine, 1 mg L−1 naphthaleneacetic acid, 30 g L−1 sucrose, 500 mg L−1, l-glutamine, 500 mg L−1 casein hydrolysis and 6.5 g L−1 agar. In addition, the combination of 2,4-dichlorophenoxyacetic acid + 6-benzyl adenine also had a better proliferative effect on callus. The effects of different combinations of growth regulators on callus proliferation efficiency were significantly different. Transfer to new medium every 13–15 days not only maintained robust callus vigor, but also yielded a larger proliferation coefficient. The techniques and conditions for embryogenic callus induction and proliferation of Korean determined here will serve as a foundation for establishing a large-scale system for somatic embryogenesis and propagation of Korean pine.

Variations in leaf economics spectrum traits for an evergreen coniferous species: Tree size dominates over environment factors

Abstract Many leaf traits strongly vary with tree size and environmental factors, but the importance of these factors to intraspecific variations of leaf traits in forest trees has rarely been simultaneously evaluated. We measured needle longevity and specific leaf area (SLA) and nitrogen (N) content of every needle age (0‐ to 4‐year old) for 65 individuals with 0.3–100 cm diameter at breast height (DBH) for an evergreen coniferous species, Pinus koraiensis Sieb. et Zucc., in Northeast China. We simultaneously evaluated the effects of tree size (DBH or tree height) and environment factors (light intensity, soil N content and water availability) on the needle longevity, SLA, foliage N content as well as the slopes of regressions of SLA and foliage N content against needle age. All of the studied leaf traits and slopes of regressions of SLA and foliage N content against needle age were significantly related to tree size. Tree height had a greater impact on SLA and area‐based leaf N content (Narea), whereas DBH was more important for needle longevity and mass‐based leaf N content (Nmass). The environment variables, light intensity, soil N content and water availability, were rather minor factors for trait variations compared with tree size. Significant influence of light intensity was found only on needle longevity, and soil N and water availability had no effects on the leaf traits. Our study clearly showed that tree size is an important driver of intraspecific variations in the key leaf traits of P. koraiensis in a natural forest. We also emphasize the importance of DBH or tree height varies depending on leaf traits, suggesting various mechanisms of size effects on the intraspecific variations in leaf traits. We suggest that ecological significance of leaf trait variations needs reconsideration incorporating tree size effect. A free Plain Language Summary can be found within the Supporting Information of this article.

How can the shade intolerant Korean pine survive under dense deciduous canopy?

The regeneration of Korean pine (Pinus koraiensis Sieb. et Zucc) is a core issue for restoration from secondary to primary forests. There is a lack of Korean pine regeneration in primary forests, compared to an abundance of regeneration in secondary forests. However, the mechanisms behind this mysterious phenomenon have not been studied. This study investigated seasonal understory light availability in addition to carbon (C) gain of understory Korean pine, nonstructural carbohydrate (NSC) storage of Korean pine in secondary forests, and the growth and survival of seedlings under manipulated light regimes. Understory light intensities in early spring and late autumn in secondary forests were significantly higher than in primary forests. The C gain of understory Korean pine occurred mostly in early spring and late autumn, whereas it was negative in the growing season (summer). Total NSC concentrations of Korean pine saplings increased between growing seasons, and decreased during the growing season. In particular, the NSC was dominated by a progressive increase in starch in early spring and by a peak in soluble sugar in late autumn. In this study, the biomass, NSC concentration and pool sizes, as well as survival rates, were positively correlated with light availability, revealing that the species is shade intolerant. The accumulated survival rate, examined in the autumn, was less correlated with biomass, but positively correlated with the carbohydrate storage in autumn. High light availability and positive C gain in early spring and late autumn are key factors affecting the growth and survival of understory seedlings. These two periods in secondary forests are crucial for the survival of seedlings by ensuring sufficient energy to live through the long-lasting dark summer. In primary forests, however, light availability was relatively stable across all seasons, especially in the leafless period, and insufficient through-canopy radiation, along with dense lateral closure, caused seedlings mortality.

Comparative study on hepatoprotection of pine nut (Pinus koraiensis Sieb. et Zucc.) polysaccharide against different types of chemical-induced liver injury models in vivo

A novel polysaccharide (PNP80b-2) was obtained from Pinus koraiensis pine nut, which has been proved to possess good hepatoprotective effects in vitro. This study comprehensively investigated its hepatoprotective activities against different types of chemical-induced liver injury in vivo. Carbon tetrachloride, alcohol and acetaminophen were used as hepatic toxicants to establish chemical pollutant-induced liver injury (CILI) model, alcohol induced-liver injury (AILI) model and drug-induced liver injury (DILI) model, respectively. The results showed that PNP80b-2 prevented elevation of biomarkers for liver injury in each model, including alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and total bilirubin (TBIL). The expression of cytochrome P450 in damaged hepatocytes was also downregulated. Additionally, PNP80b-2 enhanced hepatic antioxidant capacity through upregulating the expression of NRF2 and HO-1, thereby increasing superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activities and decreasing malondialdehyde (MDA) levels. The uncontrolled production of inflammatory factors including tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6) and cyclooxygenase-2 (COX-2) in CILI, AILI and DILI models was also suppressed by PNP80b-2. By contrast, PNP80b-2 exerted the strongest hepatoprotection against AILI model, through improving hepatic antioxidant capacity via NRF2/ARE pathway and regulating inflammation response. Thus, PNP80b-2 is a promising functional food to prevent AILI.