The Bursaphelenchus xylophilus Effector BxNMP1 Targets PtTLP-L2 to Mediate PtGLU Promoting Parasitism and Virulence in Pinus thunbergii.

Pinus is an important economic tree species, but pine wilt disease (PWD) seriously threatens the survival of pine trees. PWD caused by Bursaphelenchus xylophilus is a major quarantine disease worldwide that causes significant economic losses. However, more information about its molecular pathogenesis is needed, resulting in a lack of effective prevention and treatment measures. In recent years, effectors have become a hot topic in exploring the molecular pathogenic mechanism of pathogens. Here, we identified a specific effector, BxNMP1, from B. xylophilus. In situ hybridization experiments revealed that BxNMP1 was specifically expressed in dorsal gland cells and intestinal cells, and RT-qPCR experiments revealed that BxNMP1 was upregulated in the early stage of infection. The sequence of BxNMP1 was different in the avirulent strain, and when BxNMP1-silenced B. xylophilus was inoculated into P. thunbergii seedlings, the disease severity significantly decreased. We demonstrated that BxNMP1 interacted with the thaumatin-like protein PtTLP-L2 in P. thunbergii. Additionally, we found that the ß-1,3-glucanase PtGLU interacted with PtTLP-L2. Therefore, we hypothesized that BxNMP1 might indirectly interact with PtGLU through PtTLP-L2 as an intermediate mediator. Both targets can respond to infection, and PtTLP-L2 can enhance the resistance of pine trees. Moreover, we detected increased salicylic acid contents in P. thunbergii seedlings inoculated with B. xylophilus when BxNMP1 was silenced or when the PtTLP-L2 recombinant protein was added. In summary, we identified a key virulence effector of PWNs, BxNMP1. It positively regulates the pathogenicity of B. xylophilus and interacts directly with PtTLP-L2 and indirectly with PtGLU. It also inhibits the expression of two targets and the host salicylic acid pathway. This study provides theoretical guidance and a practical basis for controlling PWD and breeding for disease resistance.

Estimation of changes in carbon sequestration and its economic value with various stand density and rotation age of Pinus massoniana plantations in China.

Plantations actively participate in the global carbon cycle and play a significant role in mitigating global climate change. However, the influence of forest management strategies, especially planting density management, on the biomass carbon storage and production value of plantations for ensuring carbon sink benefits is still unclear. In this study, we estimated the carbon sequestration and economic value of Pinus massoniana plantations with various stand densities and rotation ages using a growth model method. The results revealed that with increasing stand age, low-density plantations at 2000 trees·ha-1 (358.80 m3·ha-1), as well as high-density plantations at 4500 trees·ha-1 (359.10 m3·ha-1), exhibited nearly identical standing volumes, which indicated that reduced inter-tree competition intensity favors the growth of larger trees during later stages of development. Furthermore, an increase in planting density led to a decrease in the average carbon sequestration rate, carbon sink, and number of trees during the rapid growth period, indicating that broader spacing between trees is favorable for biomass carbon accumulation. Further, extending the rotation period from 15 to 20 years or 25 years and reducing the optimal planting density from 3000 to 2000 trees·ha-1 increased the overall benefits of combined timber and carbon sink income by 2.14 and 3.13 times, respectively. The results highlighted that optimizing the planting density positively impacts the timber productivity and carbon sink storage of Pinus massoniana plantations and boosts the expected profits of forest managers. Thus, future afforestation initiatives must consider stand age and planting density management to shift from a scale-speed pattern to a quality-benefit design.

Superhydrophobic coatings reduce human bacterial foodborne pathogen attachment to woods used in fresh produce harvest and postharvest packing.

Wood is reportedly more difficult to maintain in hygienic condition versus other food contact materials, yet its use in produce packing and retail warrants efforts to reduce the risk of microbial pathogen contamination and attachment. This study characterized antifouling capabilities of fluorinated silanes applied to wood used in fresh edible produce handling to render the wood superhydrophobic and less supportive of bacterial pathogen attachment. Pine and oak cubic coupon surfaces were treated with 1% (w/w) silane or left untreated. Treated and untreated coupons were inoculated with Salmonella enterica or Listeria monocytogenes and held to facilitate pathogen attachment for 1, 4, or 8 h. Silane treatment of wood produced significant reductions in the proportions of strongly attaching cells for both pathogens versus loosely attaching cells (P < 0.01). Salmonella attachment demonstrated a dependency on wood treatment; silane-treated wood supported a lower fraction of strongly adhering cells (1.87 ± 1.24 log CFU/cm2) versus untreated wood (3.72 ± 0.67 log CFU/cm2). L. monocytogenes demonstrated significant declines in strongly attaching cells during extended exposure to silane-treated wood, from 7.59 ± 0.14 to 5.27 ± 0.68 log CFU/cm2 over 8 h post-inoculation. Microscopic analysis demonstrated silane treatment increased the surface roughness of both woods, leading to superhydrophobic conditions on wood surfaces, consequently decreasing strong attachment of pathogenic bacteria.

The New Nematicide Cyclobutrifluram Targets the Mitochondrial Succinate Dehydrogenase Complex in Bursaphelenchus xylophilus.

Bursaphelenchus xylophilus is a dangerous quarantine pest that causes extensive damage to pine ecosystems worldwide. Cyclobutrifluram, a succinate dehydrogenase inhibitor (SDHI), is a novel nematicide introduced by Syngenta in 2013. However, the nematocidal effect of cyclobutrifluram against plant-parasitic nematodes remains underexplored. Therefore, here, we aim to address this knowledge gap by evaluating the toxicity, effects, and mode of action of cyclobutrifluram on B. xylophilus. The result shows that cyclobutrifluram is the most effective agent, with an LC50 value of 0.1078 mg·L-1. At an LC20 dose, it significantly reduced the population size to 10.40 × 103 ± 737.56-approximately 1/23 that of the control group. This notable impact may stem from the agent's ability to diminish egg-laying and hatching rates, as well as to impede the nematodes' development. In addition, it has also performed well in the prevention of pine wilt disease, significantly reducing the incidence in greenhouses and in the field. SDH consists of a transmembrane assembly composed of four protein subunits (SDHA to SDHD). Four sdh genes were characterized and proved by RNAi to regulate the spawning capacity, locomotion ability, and body size of B. xylophilus. The mortality of nematodes treated with sdhc-dsRNA significantly decreased upon cyclobutrifluram application. Molecular docking further confirmed that SDHC, a cytochrome-binding protein, is the target. In conclusion, cyclobutrifluram has a good potential for trunk injection against B. xylophilus. This study provides valuable information for the screening and application of effective agents in controlling and preventing PWD in forests.

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.

The Characterization of a Novel PrMADS11 Transcription Factor from Pinus radiata Induced Early in Bent Pine Stem.

A novel MADS-box transcription factor from Pinus radiata D. Don was characterized. PrMADS11 encodes a protein of 165 amino acids for a MADS-box transcription factor belonging to group II, related to the MIKC protein structure. PrMADS11 was differentially expressed in the stems of pine trees in response to 45° inclination at early times (1 h). Arabidopsis thaliana was stably transformed with a 35S::PrMADS11 construct in an effort to identify the putative targets of PrMADS11. A massive transcriptome analysis revealed 947 differentially expressed genes: 498 genes were up-regulated, and 449 genes were down-regulated due to the over-expression of PrMADS11. The gene ontology analysis highlighted a cell wall remodeling function among the differentially expressed genes, suggesting the active participation of cell wall modification required during the response to vertical stem loss. In addition, the phenylpropanoid pathway was also indicated as a PrMADS11 target, displaying a marked increment in the expression of the genes driven to the biosynthesis of monolignols. The EMSA assays confirmed that PrMADS11 interacts with CArG-box sequences. This TF modulates the gene expression of several molecular pathways, including other TFs, as well as the genes involved in cell wall remodeling. The increment in the lignin content and the genes involved in cell wall dynamics could be an indication of the key role of PrMADS11 in the response to trunk inclination.

Sustainable removal of tetracycline and paracetamol from water using magnetic activated carbon derived from pine fruit waste.

This work presents highly porous magnetic activated carbon nanoparticles (MPFRC-A) derived from pine fruit residue. The MPFRC-A were produced through a three-step process: physical activation (carbonization temperature: 110-550 °C), chemical activation (H2SO4 (0.1 N, 96%)), and co-precipitation. These nanoparticles were then used to remove tetracycline (TC) and paracetamol (PC) from water. Functionalization with Fe3O4 nanoparticles on the surface of the pine fruit residue-derived activated carbon (PFRC-A) resulted in high saturation magnetization, allowing for separation from aqueous solution using an external magnet. The MPFRC-A adsorbent was characterized by Brunauer-Emmett-Teller (BET) analysis, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDX) analyses, In the experimental section, the effects of various factors on the adsorption process were investigated, including pH, contact time, initial pollutant concentrations, adsorbent dosage, and temperature. Based on these investigations, adsorption isotherm models and kinetics were studied and determined. The results showed that MPFRC-A exhibited a large specific surface area (182.5 m2/g) and a high total pore volume (0.33 cm3/g). The maximum adsorption capacity was achieved at pH 6 and 5 for PC and TC drugs with an adsorbent dose of 400 mg and an initial concentration of 20 mg/L at 25 °C. The study revealed that the experimental data were well-fitted by the Langmuir isotherm model (R2 > 0.98), with maximum uptake capacities of 43.75 mg/g for TC and 41.7 mg/g for PC. Outcomes of the adsorption thermodynamics shows non-spontaneity of the reaction and the adsorption process by all adsorbents was endothermic.

Trunk distortion weakens the tree productivity revealed by half-sib progeny determination of Pinus yunnanensis.

Twisted trunks are not uncommon in trees, but their effects on tree growth are still unclear. Among coniferous tree species, the phenomenon of trunk distortion is more prominent in Pinus yunnanensis. To expand the germplasm of genetic resources, we selected families with excellent phenotypic traits to provide material for advanced generation breeding. The progeny test containing 93 superior families (3240 trees) was used as the research material. Phenotypic measurements and estimated genetic parameters (family heritability, realistic gain and genetic gain) were performed at 9, 15, and 18 years of age, respectively. The genetic evaluation yielded the following results (1) The intra-family variance component of plant height (PH) was greater than that of the inter-family, while the inter-family variance components of other traits (diameter at breast height (DBH), crown diameter (CD), height under branches (HUB), degree of stem-straightness (DS)) were greater than that of the intra-family, indicating that there was abundant variation among families and potential for selection. (2) At half rotation period (18 years old), there was a significant correlation among the traits. The proportion of trees with twisted trunks (level 1-3 straightness) reached 48%. The DS significantly affected growth traits, among which PH and DBH were the most affected. The volume loss rate caused by twisted trunk was 18.06-56.75%, implying that trunk distortion could not be completely eliminated after an artificial selection. (3) The influence of tree shape, crown width, and trunk on volume increased, and the early-late correlation between PH, DBH and volume was extremely significant. The range of phenotypic coefficient of variation, genetic variation coefficient and family heritability of growth traits (PH, DBH, and volume) were 44.29-127.13%, 22.88-60.87%, and 0.79-0.83, respectively. (4) A total of 21 superior families were selected by the method of membership function combined with independent selection. Compared with the mid-term selection (18 years old), the accuracy of early selection (9 years old) reached 77.5%. The selected families' genetic gain and realistic gain range were 5.79-19.82% and 7.12-24.27%, respectively. This study can provide some useful reference for the breeding of coniferous species.

[Response of radial growth of Pinus wallichiana to climate change in Mount Qomolangma, Tibet, China]. / è¥¿è—ç å³°åœ°åŒºä¹”æ¾å¾„å‘ç”Ÿé•¿å¯¹æ°”å€™å˜åŒ–çš„å“åº”.

Global warming would significantly impact tree growth in the Tibetan Plateau. However, the specific effects of climate change on the radial growth of Pinus wallichiana in Mount Qomolangma are still uncertain. To investigate the responses of radial growth of P. wallichiana to climate change, we analyzed tree-ring samples in Mount Qomolangma. We removed the age-related growth trends and established three chronologies by using the modified negative exponential curve, basal area index, and regional curve standardization, and conducted Pearson correlation and moving correlation analyses to examine the association between radial growth of P. wallichiana and climatic factors. The results showed that this region had experienced a significant upward trend in temperature and that the Palmer drought severity index (PDSI) indicated a decreasing trend since 1980s, while the relative humi-dity changed from a significant upward to a downward trend around 2004, implying the climate shifted toward warmer and drier. Results of Pearson correlation analysis indicated a significant and positive relationship between the radial growth of P. wallichiana and the minimum temperature of April-June and July-September, and precipitation of January-April in the current year. The radial growth of P. wallichiana was significantly and negatively associated with the relative humidity of June, July, and August in the current year. As temperature rose after 1983, the relationship between radial growth of P. wallichiana and the minimum temperature in July and September of the current year increased from a non-significant association to a significant and positive association, while the relationship between radial growth of P. wallichiana and relative humidity in August and precipitation in September of the current year changed from non-significant correlation to a significant and negative correlation. Results of the moving correlation analysis suggested that the radial growth of P. wallichiana showed a significant and stable correlation with the July-September minimum temperature of the current year. Under the background of climate warming, the rapid increases of temperature would accelerate the radial growth of P. wallichiana in Mount Qomolangma.

Properties and Functional Analysis of Two Chorismate Mutases from Maritime Pine.

Through the shikimate pathway, a massive metabolic flux connects the central carbon metabolism with the synthesis of chorismate, the common precursor of the aromatic amino acids phenylalanine, tyrosine, and tryptophan, as well as other compounds, including salicylate or folate. The alternative metabolic channeling of chorismate involves a key branch-point, finely regulated by aromatic amino acid levels. Chorismate mutase catalyzes the conversion of chorismate to prephenate, a precursor of phenylalanine and tyrosine and thus a vast repertoire of fundamental derived compounds, such as flavonoids or lignin. The regulation of this enzyme has been addressed in several plant species, but no study has included conifers or other gymnosperms, despite the importance of the phenolic metabolism for these plants in processes such as lignification and wood formation. Here, we show that maritime pine (Pinus pinaster Aiton) has two genes that encode for chorismate mutase, PpCM1 and PpCM2. Our investigations reveal that these genes encode plastidial isoenzymes displaying activities enhanced by tryptophan and repressed by phenylalanine and tyrosine. Using phylogenetic studies, we have provided new insights into the possible evolutionary origin of the cytosolic chorismate mutases in angiosperms involved in the synthesis of phenylalanine outside the plastid. Studies based on different platforms of gene expression and co-expression analysis have allowed us to propose that PpCM2 plays a central role in the phenylalanine synthesis pathway associated with lignification.

Influence of lignin and cellulose from termite-processed biomass on biochar production and evaluation of chromium VI adsorption.

The increasing water contamination by toxic heavy metals, particularly hexavalent chromium, has become a significant environmental concern. This study explores the pyrolysis of termite-processed biomass, specifically Pinus elliottii particleboard and its termite droppings (TDs), to produce biochar and its application for chromium (VI) adsorption. Termite droppings, rich in lignin, and particleboard, rich in cellulose, were pyrolyzed at various temperatures to assess the effect of biomass composition on biochar properties. The study found that lignin-rich termite droppings produced biochar with higher fixed carbon content and specific surface area than cellulose-rich particleboard biochar. FTIR and Raman spectroscopy revealed significant molecular structure changes during pyrolysis, which influenced the adsorption capabilities of the biochar. Adsorption experiments demonstrated that TD biochar exhibited significantly higher chromium (VI) adsorption capacity, attributed to its distinct chemical composition and enhanced surface properties due to higher lignin content. These findings underscore the crucial role of lignin in producing efficient biochar for heavy metal adsorption, highlighting the practical applicability of termite-processed biomass in water purification technologies.

The Key Role of Plant Hormone Signaling Transduction and Flavonoid Biosynthesis Pathways in the Response of Chinese Pine (Pinus tabuliformis) to Feeding Stimulation by Pine Caterpillar (Dendrolimus tabulaeformis).

In nature, plants have developed a series of resistance mechanisms to face various external stresses. As understanding of the molecular mechanisms underlying plant resistance continues to deepen, exploring endogenous resistance in plants has become a hot topic in this field. Despite the multitude of studies on plant-induced resistance, how plants respond to stress under natural conditions remains relatively unclear. To address this gap, we investigated Chinese pine (Pinus tabuliformis) using pine caterpillar (Dendrolimus tabulaeformis) under natural conditions. Healthy Chinese pine trees, approximately 10 years old, were selected for studying induced resistance in Huangtuliangzi Forestry, Pingquan City, Chengde City, Hebei Province, China. Pine needles were collected at 2 h and 8 h after feeding stimulation (FS) via 10 pine caterpillars and leaf clipping control (LCC), to simulate mechanical damage caused by insect chewing for the quantification of plant hormones and transcriptome and metabolome assays. The results show that the different modes of treatments significantly influence the contents of JA and SA in time following treatment. Three types of differentially accumulated metabolites (DAMs) were found to be involved in the initial response, namely phenolic acids, lipids, and flavonoids. Weighted gene co-expression network analysis indicated that 722 differentially expressed genes (DEGs) are positively related to feeding stimulation and the specific enriched pathways are plant hormone signal transduction and flavonoid biosynthesis, among others. Two TIFY transcription factors (PtTIFY54 and PtTIFY22) and a MYB transcription factor (PtMYB26) were found to be involved in the interaction between plant hormones, mainly in the context of JA signal transduction and flavonoid biosynthesis. The results of this study provide an insight into how JA activates, serving as a reference for understanding the molecular mechanisms of resistance formation in conifers responding to mandibulate insects.

Factors limiting the potential range expansion of lodgepole pine in Interior Alaska.

Understanding the factors influencing species range limits is increasingly crucial in anticipating migrations due to human-caused climate change. In the boreal biome, ongoing climate change and the associated increases in the rate, size, and severity of disturbances may alter the distributions of boreal tree species. Notably, Interior Alaska lacks native pine, a biogeographical anomaly that carries implications for ecosystem structure and function. The current range of lodgepole pine (Pinus contorta var. latifolia) in the adjacent Yukon Territory may expand into Interior Alaska, particularly with human assistance. Evaluating the potential for pine expansion in Alaska requires testing constraints on range limits such as dispersal limitations, environmental tolerance limits, and positive or negative biotic interactions. In this study, we used field experiments with pine seeds and transplanted seedlings, complemented by model simulations, to assess the abiotic and biotic factors influencing lodgepole pine seedling establishment and growth after fire in Interior Alaska. We found that pine could successfully recruit, survive, grow, and reproduce across our broadly distributed network of experimental sites. Our results show that both mammalian herbivory and competition from native tree species are unlikely to constrain pine growth and that environmental conditions commonly found in Interior Alaska fall well within the tolerance limits for pine. If dispersal constraints are released, lodgepole pine could have a geographically expansive range in Alaska, and once established, its growth is sufficient to support pine-dominated stands. Given the impacts of lodgepole pine on ecosystem processes such as increases in timber production, carbon sequestration, landscape flammability, and reduced forage quality, natural or human-assisted migration of this species is likely to substantially alter responses of Alaskan forest ecosystems to climate change.

Climate change reduces elevational and latitudinal differences in spring phenology of pine caterpillar (Dendrolimus spectabilis Bulter).

The pine caterpillar (Dendrolimus spectabilis Bulter, Lepidoptera: Lasiocampidae), as an ectotherm, temperature plays a crucial role in its development. With climate change, earlier development of insect pests is expected to pose a more frequent threat to forest communities. Yet the quantitative research about the extent to which global warming affects pine caterpillar populations is rarely understood, particularly across various elevations and latitudes. Spring phenology of pine caterpillars showed an advancing trend with 0.8 d/10a, 2.2 d/10a, 2.2 d/10a, and 3.3 d/10a under the SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5 scenario, respectively. There was a maximum advance of 20 d in spring phenology of pine caterpillars during the 2090s, from mid-March to early March, and even late February. This study highlighted the significant advance in spring phenology at elevations >1000 m and lower latitudes. Consequently, the differences in elevational and latitudinal gradients were relatively small as the increasing temperatures at the end of the 21st century. And the average temperature in February-March was effective in explaining theses variability. These findings are crucial for adapting and mitigating to climate change.

Community assembly of ectomycorrhizal fungal communities in pure and mixed Pinus massoniana forests.

Ectomycorrhizal (EcM) fungi play an important role in nutrient cycling and community ecological dynamics and are widely acknowledged as important components of forest ecosystems. However, little information is available regarding EcM fungal community structure or the possible relationship between EcM fungi, soil properties, and forestry activities in Pinus massoniana forests. In this study, we evaluated soil properties, extracellular enzyme activities, and fungal diversity and community composition in root and soil samples from pure Pinus massoniana natural forests, pure P. massoniana plantations, and P. massoniana and Liquidambar gracilipes mixed forests. The mixed forest showed the highest EcM fungal diversity in both root and bulk soil samples. Community composition and co-occurrence network structures differed significantly between forest types. Variation in the EcM fungal community was significantly correlated with the activities of ß-glucuronidase and ß-1,4-N-acetylglucosaminidase, whereas non-EcM fungal community characteristics were significantly correlated with ß-1,4-glucosidase and ß-glucuronidase activities. Furthermore, stochastic processes predominantly drove the assembly of both EcM and non-EcM fungal communities, while deterministic processes exerted greater influence on soil fungal communities in mixed forests compared to pure forests. Our findings may inform a deeper understanding of how the assembly processes and environmental roles of subterranean fungal communities differ between mixed and pure plantations and may provide insights for how to promote forest sustainability in subtropical areas.

Utilization of organic-residues as potting media: Physico-chemical characteristics and their influence on vegetable production.

Soilless agriculture is acknowledged worldwide because it uses organic leftovers as a means of supporting intensive and efficient plant production. However, the quality of potting media deteriorates because of lower nutrient content and excessive shrinkage of most organic materials. A current study was undertaken to identify the optimal blend of locally available organic materials with desirable qualities for use as potting media. Therefore, different ingredients, viz., Pinus roxburghii needles, sugarcane bagasse, and farmyard manure were used alone or in combination as potting media to test their suitability by growing spinach as a test crop. Results showed that an increase in Pinus roxburghii needles and sugarcane bagasse decreased medium pH and electrical conductivity. Higher pH and electrical conductivity were recorded for the treatments having a higher farmyard manure ratio (≥50%) in combination. Except for pine needles 100%, pH and electrical conductivity were in the recommended range. The growth attributes include, leaves plant-1, shoot length, fresh- and dry shoot weight along with plant macronutrients (nitrogen, phosphorous, and potassium) and micronutrients (iron, copper, manganese, and zinc) content were higher in treatment pine needles 50%+farmyard manure 50% followed by pine needles 25%+farmyard manure 50%+sugarcane bagasse 25%. Moreover, the particular treatment of pine needles 50%+farmyard manure 50% exhibited the highest concentrations of macro- (nitrogen, phosphorus, and potassium) as well as micronutrients (iron, copper, manganese, and zinc) in the potting media following the harvest. This study highlights the potential of utilizing agro-industrial litter/waste as a soilless growing medium for spinach production under greenhouse conditions. When employed in appropriate proportions, this approach not only addresses disposal concerns but also proves effective for sustainable cultivation. Further research is needed to investigate the use of these wastes as potting media by mixing various particle-size ingredients.

[Seasonal variation of water utilization sources and responses to precipitation in the dominant species of broad-leaved and needle-leaved mixed forests in Mount Lushan, China]. / 庐山针阔混交林优势种水分利用来源季节变化及对降水的响应.

Elucidating the seasonal patterns of water sources for dominant species in the sub-tropical humid mountainous forest, analyzing the eco-hydrological complementarity and competition mechanisms among coexisting species, investigating the responses of plant water utilization to precipitation, could provide a theoretical basis for vegetation restoration and management. Based on the stable hydrogen and oxygen isotope technique, we analyzed the δ2H and δ18O characteristics of precipitation, xylem water from Pinus massoniana and Quercus variabilis, and soil water from 0-100 cm depth in Mount Lushan, China. The MixSIAR model, Levins index, and PS index were used to calculate the relative contribution rate of each water source, the hydrological niche breadth, and niche overlap of P. massoniana and Q. variabilis. The results showed that, in the wet season (March to July), P. massoniana primarily utilized soil water from the 0-20 cm and 20-40 cm depths, while Q. variabilis primarily utilized that from the 20-40 cm and 40-60 cm depths. During the dry season (August to September), P. massoniana and Q. variabilis utilized 40-60 cm and 60-80 cm of soil water, respectively, resulting in an increase in the depth of water absorption. In the early growing season (March to April) and the late growing season (September), there was a high hydrological niche overlap between P. massoniana and Q. variabilis, resulting in intensitive water competition. In the middle of the growing season (May to August), the water source was adequately allocated, and the hydrolo-gical niche was segregated to meet the high transpiration demand. Q. variabilis primarily utilized soil water from a depth of 60-80 cm and 60-80 cm before a precipitation event, and from a depth of 0-20 cm and 20-40 cm after the event. In contrast, P. massoniana primarily utilized soil water from a depth of 0-20 cm and 20-40 cm both before and after a precipitation event. In conclusion, water utilization patterns of P. massoniana and Q. variabilis exhibited a seasonal trend, with shallow water uptake during the rainy season and deep water uptake during the dry season. These species are capable of efficiently allocating water resources during the peak growth season, and their root systems actively respond to change in soil moisture level. They have strong adaptability to extreme precipitation events and exhibit remarkable water conservation capabilities.

[Short-term nitrogen addition reduces soil microbial nitrogen fixation rate in subtropical Pinus taiwanensis and Castanopsis faberi forests]. / çŸ­æœŸæ°®æ·»åŠ é™ä½Žäºšçƒ­å¸¦é»„å±±æ¾æž—å’Œç½—æµ®æ ²æž—åœŸå£¤å¾®ç”Ÿç‰©å›ºæ°®é€ŸçŽ‡.

Biological nitrogen (N) fixation is an important source of N in terrestrial ecosystems, but the response of soil microbial N fixation rate to N deposition in different forest ecosystems still remains uncertain. We conducted a field N addition experiment to simulate atmosphere N deposition in subtropical Pinus taiwanensis and Castanopsis faberi forests. We set up three levels of nitrogen addition using urea as the N source: 0 (control), 40 (low N), and 80 g N·hm-2·a-1(high N) to examine the chemical properties, microbial biomass C, enzyme activities, and nifH gene copies of top soils (0-10 cm). We also measured the microbial N fixation rate using the 15N labeling method. Results showed that N addition significantly reduced the soil microbial N fixation rate in the P. taiwanensis and C. faberi forests by 29%-33% and 10%-18%, respectively. Nitrogen addition significantly reduced N-acquiring enzyme (i.e., ß-1, 4-N-acetylglucosaminidase) activity and nifH gene copies in both forest soils. There was a significant positive correlation between the microbial N fixation rate and soil dissolved organic C content in the P. taiwanensis forest, but a significant negative relationship between the rate of soil microbial nitrogen fixation and NH4+-N content in the C. faberi forest. Overall, soil microbial N fixation function in the P. taiwanensis forest was more sensitive to N addition than that in the C. faberi forest, and the factors affecting microbial N fixation varied between the two forest soils. The study could provide insights into the effects of N addition on biological N fixation in forest ecosystems, and a theoretical basis for forest management.

Study on the extraction, purification, stability, free radical scavenging kinetics, polymerization degree and characterization of proanthocyanidins from Pinus koraiensis seed scales.

To efficiently harness resources from Pinus koraiensis seed scales, a type of forestry waste, rigorous studies on the extraction, purification, stability, and free radical scavenging capacity of the proanthocyanidins derived from these seed scales were conducted. Kinetic models showed that under ultrasonic conditions, the proanthocyanidins content reached 2.66 mg/g within 0.5 h. The optimal storage parameters include darkness, 4 °C, and pH 4. The degrees of polymerization of the mixture and the high- and low-polymer components were 4.89, 7.42 and 3.07, respectively, with the low-polymer component exhibiting the highest radical scavenging activity. Through HPLC-QE-MS/MS, 1H NMR, and FT-IR analyses, we identified proanthocyanidin B1, proanthocyanidin B2, (-)-epicatechin, and polymeric trimer esters. The Pinus koraiensis proanthocyanidins exhibited a high molecular weight, a complex internal molecular structure, and commendable stability, with crystallization requiring elevated temperatures. Therefore, the proanthocyanidins from Pinus koraiensis seed scales have emerged as highly promising novel natural antioxidants.

Tree rings reveal the transient risk of extinction hidden inside climate envelope forecasts.

Given the importance of climate in shaping species' geographic distributions, climate change poses an existential threat to biodiversity. Climate envelope modeling, the predominant approach used to quantify this threat, presumes that individuals in populations respond to climate variability and change according to species-level responses inferred from spatial occurrence data-such that individuals at the cool edge of a species' distribution should benefit from warming (the "leading edge"), whereas individuals at the warm edge should suffer (the "trailing edge"). Using 1,558 tree-ring time series of an aridland pine (Pinus edulis) collected at 977 locations across the species' distribution, we found that trees everywhere grow less in warmer-than-average and drier-than-average years. Ubiquitous negative temperature sensitivity indicates that individuals across the entire distribution should suffer with warming-the entire distribution is a trailing edge. Species-level responses to spatial climate variation are opposite in sign to individual-scale responses to time-varying climate for approximately half the species' distribution with respect to temperature and the majority of the species' distribution with respect to precipitation. These findings, added to evidence from the literature for scale-dependent climate responses in hundreds of species, suggest that correlative, equilibrium-based range forecasts may fail to accurately represent how individuals in populations will be impacted by changing climate. A scale-dependent view of the impact of climate change on biodiversity highlights the transient risk of extinction hidden inside climate envelope forecasts and the importance of evolution in rescuing species from extinction whenever local climate variability and change exceeds individual-scale climate tolerances.