Stochastic process drives the dissimilarity in biodiversity patterns between Pinus kwangtungensis coniferous forest and evergreen deciduous broad-leaved mixed forest in karst area.

Pinus kwangtungensis is an endangered evergreen conifer tree species, and its in situ conservation has been considered one of the most critical issues. However, relative protection is limited by the lack of understanding of its community structure and underlying assembly processes. To study how the species diversity and assembly processes of Pinus kwangtungensis coniferous forest (CF) differed with regional climax community, this study established a series forest dynamic plots both in CF and evergreen deciduous broadleaved mixed forest (EDBM). By performing comparison analysis and PER-SIMPER approaches, we quantified the differences in species diversity and community assembly rules. The results showed that the species α-diversity of CF differed greatly from the EDBM both in species richness and evenness. In addition, the stochastic process acted a more important role in determining species composition, indicating the uncertainty in presence of species. The soil phosphorus and changeable calcium content were the main factors driving the differences in biodiversity, which the importance of soil nutrient factors in driving species composition. Our study highlighted that we should consider the community structure and ecological process when conducting conservation of Pinus kwangtungensis.

Response of soil-microbe-extracellular enzyme stoichiometric characteristics to nitrogen deposition in a Pinus yunnanensis forest in central Yunnan Province, Southwest China.

To understand the effects of nitrogen deposition on element cycling and nutrient limitation status in forest ecosystems, we examined the effects of nitrogen deposition on the stoichiometric characteristics of forest soil-microbial-extracellular enzymes in Pinus yunnanensis forest. We conducted a field experiment with control (CK, 0 g N·m-2·a-1), low nitrogen (LN, 10 g N·m-2·a-1), medium nitrogen (MN, 20 g N·m-2·a-1) and high nitrogen (HN, 25 g N·m-2·a-1) since 2019. We collected soil samples (0-5 cm, 5-10 cm and 10-20 cm) at September 2022, and measured the contents of soil organic, total nitrogen, total phosphorus, microbial biomass carbon, nitrogen and phosphorus (MBC, MBN, MBP) and the activities of C, N, and P acquisition enzymes. The results showed that nitrogen deposition significantly reduced soil organic content, C:N and C:P by 6.9%-29.8%, 7.6%-45.2% and 6.5%-28.6%, and increased soil total N content and N:P by 10.0%-45.0% and 19.0%-46.0%, respectively. Nitrogen addition did not affect soil total P content. Except for soil C:N and C:P, soil nutrient content and stoichiometric ratio were highest in 0-5 cm soil layer. MN and HN treatments significantly decreased MBN by 11.0%-12.7%. MBC, MBP, and their stoichiometry did not change significantly under nitrogen deposition. Soil microbial nutrient content in 0-5 cm soil layer was significantly higher than that in other soil layers. Nitrogen deposition significantly decreased the activities of cellobiose hydrolase and leucine aminopeptidase (decreased by 14.5%-16.2% and 48.7%-66.3%). HN treatment promoted ß-1,4-glucosidase activity (increased by 68.0%), but inhibited soil enzyme stoichiometric carbon to nitrogen ratio and nitrogen to phosphorus ratio (decreased by 95.4% and 88.4%). LN and MN treatment promoted ß-1,4-N-acetylglucosaminidase activity (increased by 68.3%-116.6%), but inhibited enzyme stoichiometric carbon to phosphorus ratio (decreased by 14.9%-29.4%). Alkaline phosphatase activity had no significant change. Soil enzyme activities were significantly decreased with increasing soil depth. Soil total N and total P and microbial nutrients were negatively correlated with vector angle (representing microbial nitrogen or phosphorus limitation), while vector length (representing microbial carbon limitation) was consistently significantly positively correlated with vector angle, suggesting the synergistic promotion between microbial carbon limitation and phosphorus limitation. Nitrogen deposition gradually shifted to phosphorus limitation while alleviating microbial nitrogen limitation in P. yunnanensis forest. In addition, microbial activities in this region was limited by C availability, and the relationship between microbial C and P limitation was proportional.

Growth difference of planted Pinus koraiensis from different provenances in Maoer Mountain, China.

In order to analyze the growth pattern of tree height of planted Pinus koraiensis and screen the provenances with fastest growth, we grouped the provenances using the differences in tree height, diameter at breast height (DBH) and volume of timber of 234 individuals of planted P. koraiensis from 26 provenances in Maoershan Experimental Forest Farm. We constructed the growth equation for tree height by combining the base models of Gompertz, Korf, Richards, Logistic, and Schumacher, and then selected the optimal one. We introduced the prove-nance grouping as a dummy variable into the base model, and evaluated the optimal tree height growth equation by a comprehensive evaluation of the model according to the coefficient of determination (R2), the root-mean-square error (RMSE), the Akaikei Information Criterion (AIC), and the model's predictive precision (FP). The results showed that the growth traits of the 26 provenances had significant difference among the groups, and that tree height and DBH showed significant differences among the provenances. According to the comprehensive consideration of different growth traits, the four groups of provenance growth were divided into group A (Wuying, Hebei, Linjiang, Dongfanghong, Huanan, Lushuihe, Fangzheng) >group B (Aihuisanzhan, Liangshui, Tieli, Qinghe) > group C (Wuyiling, Zhanhe, Liangzihe, Baihe, Chaihe, Caohekou, Bajiazi) >group D (Tongzigou, Dashitou, Wangqing, Helong, Yanshou, Dahailin, Xiaobeihu, Muling). The optimal base tree height growth model of the four groups was the Gompertz model, and the fitting accuracy of the model after the introduction of dummy variables (R2=0.9353) was higher than that of the base model (R2=0.9303), and the model prediction accuracy was also improved. The tree height growth curves of each provenance group conformed to the "S"-shaped rule of change. There were obvious differences among the groups, with the best performance of the provenances in group A. The growth of P. koraiensis from different provenances was different, and the tree height growth model with dummy variables of provenance groups could effectively improve the prediction accuracy of the model, reflect the differences in height growth of P. koraiensis of different provenances, which could provide the scientific basis for the selection and cultivation of P. koraiensis plantations.

Rhizosphere effects and microbial N limitations drive the root N limitations in the rhizosphere during secondary succession in a Pinus tabuliformis forest in North China.

Introduction: Rhizosphere effects (REs) have recently been identified as important regulators of root and microbial nutrient acquisition and are positively involved in nutrient cycling of belowground carbon (C), nitrogen (N), and phosphorus (P). Nutrient conditions of the fine roots and soil N are likely to influence REs. Still, it is unclear how REs of soil nutrients themselves variably impact the supply of nutrients to plants in terms of the responses to soil N due to succession. Methods: In this study, we applied both fine roots and extracellular enzymes for vector analysis and stoichiometry of N:P to explore the metabolic limitations of roots and rhizospheric soil microbes and their relationships with REs across five levels of soil N (0, 5, 10, 15, and 20 kg N m-2 year-1) along successional age classes of 42, 55, and 65 years in a Pinus tabuliformis forest. Results: Overall, the metabolism of root and rhizospheric soil microbes was mediated by soil N. N limitation of roots initially decreased before increasing, whereas that of microbes demonstrated opposite trends to the N levels owing to competition for inorganic N between them by REs of NO3 --N. However, N limitations of both roots and microbes were alleviated in young stands and increased with succession after the application of N. In addition, root N limitations were manipulated by REs of three different soil N-related indicators, i.e., total N, NH4 +-N, and NO3 --N. Rhizospheric soil microbial N limitation was almost unaffected by REs due to their strong homeostasis but was an important driver in the regulation of root N limitation. Discussion: Our results indicated that successional age was the most critical driver that directly and indirectly affected root N metabolism. However, the level of N application had a slight effect on root N limitation. Microbial N limitation and variations in the REs of N indicators regulated root N limitation in the rhizosphere. As a result, roots utilized REs to sequester N to alleviate N limitations. These findings contribute to novel mechanistic perspectives on the sustainability of N nutrition by regulating N cycling in a system of plant-soil-microbes in the rhizosphere to adapt to global N deposition or the heterogeneous distribution of bioavailable soil N with succession.

Local carbon reserves are insufficient for phloem terpene induction during drought in Pinus edulis in response to bark beetle-associated fungi.

Stomatal closure during drought inhibits carbon uptake and may reduce a tree's defensive capacity. Limited carbon availability during drought may increase a tree's mortality risk, particularly if drought constrains trees' capacity to rapidly produce defenses during biotic attack. We parameterized a new model of conifer defense using physiological data on carbon reserves and chemical defenses before and after a simulated bark beetle attack in mature Pinus edulis under experimental drought. Attack was simulated using inoculations with a consistent bluestain fungus (Ophiostoma sp.) of Ips confusus, the main bark beetle colonizing this tree, to induce a defensive response. Trees with more carbon reserves produced more defenses but measured phloem carbon reserves only accounted for c. 23% of the induced defensive response. Our model predicted universal mortality if local reserves alone supported defense production, suggesting substantial remobilization and transport of stored resin or carbon reserves to the inoculation site. Our results show that de novo terpene synthesis represents only a fraction of the total measured phloem terpenes in P. edulis following fungal inoculation. Without direct attribution of phloem terpene concentrations to available carbon, many studies may be overestimating the scale and importance of de novo terpene synthesis in a tree's induced defense response.

Unveiling the Chemical Constituents and Inhibitory Roles of Extracts from Pinus pinea L. Nut and Nutshell: A Novel Source for Pharmaceutical Antimicrobials.

Antibiotic resistance in infectious diseases has been a serious problem for the last century, and scientists have focused on discovering new natural antimicrobial agents. Pinus pinea has been used as a natural pharmacotherapeutic agent with antimutagenic, anticarcinogenic, and high antioxidant properties. In this study, GC-MS and LC-HR/MS were employed to analyze Pinus pinea L. nut and nutshell extracts. DPPH radical scavenging assay was performed to analyze the antioxidant properties of the extracts, but no activity was determined. GC-MS analysis showed that linoleic, oleic, and palmitic acids were the three most dominant fatty acids in nut and nutshell extracts, with ratios between 6.75% and 47.06% (v/v). LC-HR/MS revealed that the nutshell methanol extract had a higher phenolic content than other extracts, with vanillic acid (1.4071 mg/g). Antimicrobial activity assays showed that the minimum inhibitory concentrations (MIC) of the extracts varied between 5.94 and 190 mg/mL, and the most significant inhibition was seen in the nutshell methanol extract (MICs: between 5.94 and 47.5 mg/mL). Consequently, the antimicrobial activity of the extracts can be attributed to the dense fatty acids they contain, and the nutshell methanol extract showed the most potent inhibition related to the abundance of phenolic compounds in the extract.

Transcriptomic Identification of Potential C2H2 Zinc Finger Protein Transcription Factors in Pinus massoniana in Response to Biotic and Abiotic Stresses.

Biotic and abiotic stresses have already seriously restricted the growth and development of Pinus massoniana, thereby influencing the quality and yield of its wood and turpentine. Recent studies have shown that C2H2 zinc finger protein transcription factors play an important role in biotic and abiotic stress response. However, the members and expression patterns of C2H2 TFs in response to stresses in P. massoniana have not been performed. In this paper, 57 C2H2 zinc finger proteins of P. massoniana were identified and divided into five subgroups according to a phylogenetic analysis. In addition, six Q-type PmC2H2-ZFPs containing the plant-specific motif 'QALGGH' were selected for further study under different stresses. The findings demonstrated that PmC2H2-ZFPs exhibit responsiveness towards various abiotic stresses, including drought, NaCl, ABA, PEG, H2O2, etc., as well as biotic stress caused by the pine wood nematode. In addition, PmC2H2-4 and PmC2H2-20 were nuclear localization proteins, and PmC2H2-20 was a transcriptional activator. PmC2H2-20 was selected as a potential transcriptional regulator in response to various stresses in P. massoniana. These findings laid a foundation for further study on the role of PmC2H2-ZFPs in stress tolerance.

Dependence of Pinus sylvestris (Pinaceae) Radial Growth on Meteorological Conditions and Anthropogenic Air Pollution: Data from Northwestern Part of Murmansk Oblast.

The influence of meteorological factors and anthropogenic air pollution on the radial growth of the Scots pine Pinus sylvestris L. was studied as dependent on the distance from the Pechenganickel mining and metallurgical plant (Nikel, Murmansk region). Three (control, buffer, and impact) zones of the pollution gradient were identified based on the contents of main polluting elements (S, Ni, and Cu) in the forest litter. A significant weakening of pine stands was observed in the impact zone and attributed to the combined effect of long-term anthropogenic pollution of the 1970s and unfavorable weather events of the mid-1980s. As the emission decreased from 1988 to 2018, the radial increment of P. sylvestris was observed to increase significantly (by up to 44%) in the impact zone and to remain much the same in the control and buffer zones. More recently, the radial increment of trees in the impact zone reached and even exceeded the values observed in the control zone, although the trees examined were relatively old. The finding demonstrated again the high adaptive capacity of P. sylvestris.

Watering the trees for the forest: Drought alleviation in oaks and pines by ancestral ditches.

Traditional ditches ("acequias" in Spanish) derive meltwater and infiltrate groundwater providing ecological services downstream in the semi-arid Sierra Nevada range (SE Spain). Therefore, they may act as a nature-based solution by alleviating drought stress in trees growing near ditches by enhancing growth and reducing their intrinsic water-use efficiency (iWUE). Such a mitigation role of acequias is critical given that some oak (Quercus pyrenaica) and pine (Pinus sylvestris) stands reach their xeric distribution limits in Europe. We compared tree-ring width data and wood δ13C, a proxy of iWUE, in oak and pine stands located near or far (control) from ditches with different infiltration capacity in two watersheds. We assessed how trees responded to climate data, drought stress, and vegetation greenness through correlations and resilience indices. Oak trees located near ditches grew more and responded less to precipitation, soil moisture, a drought index, and greenness than control trees. In pines, we did not find this pattern, and ditch trees grew more than control trees only during an extremely dry year (1995). Climate-growth correlations suggested a longer growing season in ditch pines. Growth of ditch oaks from the "Acequia Nueva" (AN), with high infiltration capacity, responded more to autumn soil moisture and showed the lowest δ13C. Growth was enhanced by cool-wet spring conditions in pines and also by warm-wet conditions in the prior winter in the case of oaks. Control trees showed lower resistance to drought. Control trees presented higher wood δ13C values except for old oaks from the "Acequia Grande" (AG) site which may show long-term acclimation. Traditional ditches alleviate drought stress in oak and pine stands subjected to regional xeric climate conditions.

Hydrothermal environments lead to differences in the radial growth response of Pinus tabulaeformis to climate in the monsoon marginal zone, Northwestern China.

Regional climatic differences increase the complexity of tree radial growth responses to climate change in the monsoon marginal zones and may alter the carbon sequestration capacity of forests. In this study, we collected cores of Pinus tabulaeformis trees at nine sampling sites across different regions. We analysed the relationship between tree-ring width chronology and climatic factors at different sites using dendroecological methods. We used the tree-ring index to calculate resistance, recovery, and resilience as well as to explore the capacity of radial growth to cope with drought events. The results indicate that (1) Drought was the primary factor limiting tree growth, and tree-ring climate response patterns varied across three regions. Tree growth was sensitive to both temperature and precipitation in the eastern Qilian Mountains, while it was more sensitive to temperature in the Hassan Mountains and more sensitive to precipitation in the Helan Mountains. (2) The tree-ring climate response pattern remained unstable over time, and the relative influence of current climate on tree growth increased. (3) The ecological resilience of trees to extreme events varies across three regions, which could be attributed to regional moisture conditions and the duration of drought. In the context of the management and protection of trees in the study area in the future, more attention should be paid to the elasticity of tree growth after drought events.

Recovery of Scots Pine Seedlings from Long-Term Zinc Toxicity.

We studied the recovery of the growth and physiological parameters of Scots pine seedlings after long-term zinc toxicity. The removal of excess zinc from the nutrient solution resulted in the rapid recovery of primary root growth but did not promote the initiation and growth of lateral roots. The recovery of root growth was accompanied by the rapid uptake of manganese, magnesium, and copper. Despite the maximum rate of manganese uptake by the roots, the manganese content in the needles of the recovering plants did not reach control values during the 28 days of the experiment, unlike magnesium, iron, and copper. In general, the recovery of ion homeostasis eliminated all of the negative effects on the photosynthetic pigment content in the needles. However, these changes, along with recovery of the water content in the needles, were not accompanied by an increase in the weight gain of the recovering seedlings compared with that of the Zn-stressed seedlings. The increased accumulation of phenolic compounds in the needles persisted for a long period after excess zinc was removed from the nutrient solution. The decreased lignin content in the roots and needles is a characteristic feature of Zn-stressed plants. Moreover, the removal of excess zinc from the nutrient solution did not lead to an increase in the lignin content in the organs.

Effects of Low-Temperature Stress on Physiological Characteristics and Microstructure of Stems and Leaves of Pinus massoniana L.

Pinus massoniana L. is one of the most important conifer species in southern China and is the mainstay of the forest ecosystem and timber production, yet low temperatures limit its growth and geographical distribution. This study used 30-day-old seedlings from families of varying cold-tolerance to examine the morphological traits of needles and stems, chlorophyll fluorescence characteristics, protective enzymes, and changes in starch and lignin under different low-temperature stresses in an artificial climate chamber. The results showed that the seedlings of Pinus massoniana exhibited changes in phenotypic morphology and tissue structure under low-temperature stress. Physiological and biochemical indexes such as protective enzymes, osmoregulatory substances, starch, and lignin responded to low-temperature stress. The cold-tolerant family increased soluble sugars, starch grain, and lignin content as well as peroxidase activity, and decreased malondialdehyde content by increasing the levels of actual photochemical efficiency (ΦPSII), electron transport rate (ETR), and photochemical quenching (qP) to improve the cold tolerance ability. This study provides a reference for the selection and breeding of cold-tolerant genetic resources of Pinus massoniana and the mechanism of cold-tolerance, as well as the analysis of the mechanism of adaptation of Pinus massoniana in different climatic regions of China.

Experimental Induction of Extreme Indented Growth Rings (Hazel Wood) in Pinus halepensis Miller by Wide and Long Parallel Bark and Vascular Cambium Woundings.

Indented growth rings were found long ago to be experimentally induced in Pinus halepensis Miller by thin parallel axial scratching of the bark up to the vascular cambium with a sharp blade. Here, we show that when the bark and vascular cambium of P. halepensis are wounded by wide and long parallel axial wounds ("windows") rather than by thin scratches, the induced indented growth rings become dramatically more indented. All ten trees that were wounded by long parallel "windows" responded with very strong growth (especially in the first two years) that resulted in the formation of very conspicuous, extremely indented growth rings in the wood formed in between the long and wide woundings. This is true for both the trunks that were wounded all around their circumference and those that were wounded only in part of their circumference. We also suggest further lines of research.

Physiological trait coordination and variability across and within three Pinus species.

Studies have explored how traits separate plants ecologically and the trade-offs that underpin this separation. However, uncertainty remains as to the taxonomic scale at which traits can predictably separate species. We studied how physiological traits separated three Pinus (Pinus banksiana, Pinus resinosa, and Pinus strobus) species across three sites. We collected traits from four common leaf and branch measurements (light-response curves, CO2-response curves, pressure-volume curves, and hydraulic vulnerability curves) across each species and site. While common, these measurements are not typically measured together due to logistical constraints. Few traits varied across species and sites as expected given the ecological preferences of the species and environmental site characteristics. Some trait trade-offs present at broad taxonomic scales were observed across the three species, but most were absent within species. Certain trade-offs contrasted expectations observed at broader scales but followed expectations given the species' ecological preferences. We emphasize the need to both clarify why certain traits are being studied, as variation in unexpected but ecologically meaningful ways often occurs and certain traits might not vary substantially within a given lineage (e.g. hydraulic vulnerability in Pinus), highlighting the role a trait selection in trait ecology.

Resin acid δ13C and δ18O as indicators of intra-seasonal physiological and environmental variability.

Understanding the dynamics of δ13C and δ18O in modern resin is crucial for interpreting (sub)fossilized resin records and resin production dynamics. We measured the δ13C and δ18O offsets between resin acids and their precursor molecules in the top-canopy twigs and breast-height stems of mature Pinus sylvestris trees. We also investigated the physiological and environmental signals imprinted in resin δ13C and δ18O at an intra-seasonal scale. Resin δ13C was c. 2‰ lower than sucrose δ13C, in both twigs and stems, likely due to the loss of 13C-enriched C-1 atoms of pyruvate during isoprene formation and kinetic isotope effects during diterpene synthesis. Resin δ18O was c. 20‰ higher than xylem water δ18O and c. 20‰ lower than δ18O of water-soluble carbohydrates, possibly caused by discrimination against 18O during O2-based diterpene oxidation and 35%-50% oxygen atom exchange with water. Resin δ13C and δ18O recorded a strong signal of soil water potential; however, their overall capacity to infer intraseasonal environmental changes was limited by their temporal, within-tree and among-tree variations. Future studies should validate the potential isotope fractionation mechanisms associated with resin synthesis and explore the use of resin δ13C and δ18O as a long-term proxy for physiological and environmental changes.

[Temporal Variations in Community Structure and Function of Root-associated Fungi Associated with Pinus sylvestris var. mongholica Plantations in the Mu Us Sandy Land].

To illuminate the temporal variations in the structure and functional groups of the root-associated fungal community associated with Mongolian pine Pinus sylvestris var. mongholica plantations in the Mu Us Sandy Land, P. sylvestris var. mongholica plantations with different stand ages （23, 33, and 44 a） were targeted. The community compositions and main drivers of root-associated fungi at different months and stand ages were identified using the Illumina high-throughput sequencing method. The results indicated that： ① There was a distinct temporal distribution in the root-associated fungal community, the sampling month had a significant effect on the diversity of root-associated fungi （P<0.05）, and the values were higher in May and July. The stand age had no significant effect on the diversity of root-associated fungi （P>0.05） and decreased gradually with increasing stand age. ② The dominant phylum of the root-associated fungal community was Ascomycota. The relative abundance of fungal function groups was different within each month and stand age, and the dominant groups were saprotroph-symbiotroph, undefined saprotroph, and ectomycorrhizal fungi. The indicator genera of ectomycorrhizal fungi in May, July, and September were Melanoleuca, Amphinema, and Tricholoma, respectively. ③ The temporal distribution of the root-associated fungal community was significantly affected by annual relative humidity, annual precipitation, soil porosity, ammonia nitrogen, annual sunshine duration, annual temperature, and soil water content （P<0.05）. Soil organic carbon content, soil porosity, annual precipitation, and annual relative humidity were the main factors that significantly affected the indicator genus of the root-associated fungal community. Our results demonstrated that the temporal distribution of the root-associated fungal community was shaped by climate and soil properties, whereas stand age contributed less. This improved information will provide a theoretical basis for the sustainable management of P. sylvestris var mongholica plantations.

Chemical Composition and In Vitro Bioactivities of Extracts from Cones of P. halepensis, P. brutia, and P. pinea: Insights into Pharmaceutical and Cosmetic Potential.

Various parts of the Pinaceae species, a traditional plant, have potential health benefits and exhibit antibacterial, anti-cancer, and antioxidant activities. This study aims to investigate the biochemical properties of both petal (P) and core (C) fractions from pinecones of P. halepensis (PA), P. brutia (PB), and P. pinea (PP). Pinecones were manually separated into P and C, which were then milled to investigate maceration with solvents of increasing polarity: cyclohexane (1SV), ethyl acetate (2SV), and methanol (3SV) at 20 °C. Spectrophotometry was utilized to quantify the total phenolic content (TPC) and to assess bioactivities. Gas chromatography with mass spectrometry (GC-MS) and high-performance liquid chromatography (HPLC) were employed to identify the chemical composition. 3SV extracts demonstrated the highest TPC and a significant anti-oxidant potential. PA-P-3SV exhibited the highest TPC (460.66 mg GAE/g DW) and PP-P-3SV displayed the best IC50 (10.54 µg/mL) against DPPH. 1SV and 2SV extracts showed interesting anticancer activity against Hela and HepG2 cells. No significant toxic effect of P and C extracts from pinecones was observed on HEK-293 cells. GC-MS analysis unveiled 46 volatile compounds, of which 32 were detected for the first time in these species. HPLC analysis identified 38 compounds, of which 27 were not previously detected in these species. This study highlights the significant potential of pinecones as a rich source of bioactive compounds.

Viability and integrity of Pinus densiflora seeds stored for 20 years at three different temperatures.

Storage temperature is one of the most important factors determining seed longevity in the genebank. This study aimed to investigate the effect of storage temperature on the seed viability and physiological integrity after a 20-year storage period of Pinus densiflora, a tree species of ecological and economic significance in South Korea. To this end, seeds were collected and stored dry for 20 years at -18°C, 4°C and 25°C. Germination tests were conducted to assess seed viability and vigour, electrolyte leakage analysis was performed to assess cell membrane integrity, and carbohydrate analysis was conducted to assess metabolic integrity during germination. The results revealed that over 20 years, seeds stored at -18°C maintained a high germination percentage (GP; 89%), comparable to initial GP (91%), whilst those stored at 4°C exhibited a decline in GP (44%) along with a decrease in vigour. Seeds stored at 25°C lost their viability entirely. Electrical conductivity of the leachate and leakage of inorganic compounds and soluble sugars were higher with elevated storage temperature, indicating increased imbibition damage. Additionally, changes in carbohydrate content during germination revealed that the loss of viability according to storage temperature is associated with reduced storage reserve utilization and altered carbohydrate metabolism during germination. These results enhance our understanding of the effect of seed storage temperature on longevity and physiological changes of aging in the genebank, serving as a reference for establishing conservation strategies for Pinus densiflora.

Comparison of thermal, rheological properties of Finnish Pinus sp. and Brazilian Eucalyptus sp. black liquors and their impact on recovery units.

Black liquor (BL) is the major bioproduct and biomass fuel in pulp mill processes. However, the high viscosity of BL makes it a challenging material to work with, resulting in issues with evaporators and heat exchangers during its transport and processing. The thermal and rheological properties of BLs from Pinus sp. (PBL) and Eucalyptus sp. (EBL) were studied. FTIR spectra revealed the presence of the characteristic functional groups and the chemical composition in liquors. TGA/DTG curves showed three characteristic degradation stages related to evaporation of water, pyrolysis of organic groups, and condensation of char. Rheologically, liquors are classified as non-Newtonian and with comportment pseudoplastic. Their rheological dynamic shear properties included a linear viscoelastic region up to 1% shear strain, while frequency sweeps showed that storage modulus (G') > loss modulus (G''), thus confirming the solid-like behavior of both BLs. The rheological study demonstrated that increasing the temperature and oscillatory deformations of PBL and EBL decreased their degree of viscoelasticity, which could favor their pumping and handling within the pulp mill, as well as the droplet formation and swelling characteristics in the recovery furnace.

Inter-generational consistency of the ectomycorrhizal fungal community in a mixed pine-cedar post-fire stand.

The mutualistic interaction between trees and ectomycorrhizal fungi (EMF) can have a major effect on forest dynamics and specifically on seedling establishment. Here, we compared the EMF community composition associated with the roots of young saplings and mature trees of two co-habiting Pinaceae: Pinus halepensis and Cedrus deodara growing together in a post-fire forest plot, using fungal ITS metabarcoding. We found that the differences in the EMF community between the two sapling groups were mostly attributed to changes in the relative abundance of specific fungal species, with little species turnover. Specifically, Tomentella showed high abundance on pine roots, while Tuber, Russula and Sebacina were more common on the roots of cedars. The physical proximity to a specific host species was correlated with the EMF community composition of young saplings. Specifically, regardless of the sapling's own identity, the roots of saplings growing next to mature cedars had higher abundance of Tuber species, while Tomentella coerulea (Höhn. & Litsch), Russula densifolia (Secr. ex Gillet) and Tuber nitidum (Vittadini) dominated saplings next to mature pines. Cedar saplings' shoot structure was correlated with a specific EMF species. Overall, these results suggest that when germinating next to mature trees, the EMF community of saplings could be determined by extrinsic factors such as the small-scale distribution of mature trees in the forest.