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.

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.

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.

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.

As a component of the biogeochemical cycle, litterfall contributes carbon and nutrients to forest ecosystems by transferring organic material to mineral soil. Litterfall therefore serves as an important indicator for soil fertility and ecosystem health. This study aimed to determine the impact of different levels of thinning (light, moderate, and heavy) on litterfall quantity (needles, branches, bark, cones, and miscellaneous parts) and on the amount of carbon and nutrients entering the ecosystem in black pine afforestation areas. Three levels of low thinning, namely light, moderate, and heavy thinning (15%, 25%, and 35% of breast height area, respectively), were applied as treatments. Additionally, a control plot was included in the experiment. Litterfall samples were collected four times per year (once per season) from 12 treatment plots for three years. In the laboratory, dry weight measurements and analyses of carbon and macro-micro nutrient elements (N, P, K, Ca, Mg, S, Na, Fe, Cu, Zn, and Mn) were performed on litterfall samples taken from the field. Differences between treatments in terms of litterfall and the amount of carbon and nutrient elements entering the ecosystem were evaluated through variance analysis and the Duncan test. According to the findings, the quantity of litterfall input into the forest floor was highest in the control treatment, at 6,543 kg ha-1 year-1 and lowest in the heavy treatment, at 4,378 kg ha-1 year-1, showing a significant variation in litterfall quantity. The input of C to the soil ranged between 2,233 kg ha-1 year-1 and 3,347 kg ha-1 year-1 depending on thinning treatment. Although thinning treatment reduced C input to the soil, there was no significant difference among treatments. This also applied to nutrient elements such as N, P, K, Mg, and S. Needles constituted the majority of litterfall components (60%) and had the highest C density among all components, at 51.2%. The weighted carbon ratio for litterfall was calculated at 50.8%. Considering carbon-focused planning, performing moderate thinning interventions in the study area or similar pine-afforested areas may be a suitable option for maintaining the sustainability and health of the forest.

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.

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.
全球气候变暖会对青藏高原地区树木生长产生显著影响,然而,目前有关气候变化对西藏乔松径向生长的影响尚不清楚。本研究以西藏珠峰地区乔松为对象,开展树木年轮采样与处理,采用修正的负指数函数法、区域曲线标准法和断面积增量法去除生长趋势,建立年表,运用相关分析、滑动相关分析方法探究乔松径向生长与气候因子的关系。结果表明:在1980s后,该区域温度出现显著上升趋势,帕默尔干旱指数(PDSI)出现降低趋势,而相对湿度在2004年前后由显著上升转变成下降趋势,区域气候呈现暖干化。相关分析表明,乔松径向生长与当年4—6月和7—9月的最低温度呈显著正相关,与当年6—8月相对湿度呈显著负相关,与当年1—4月降水量呈显著正相关。1983年升温突变后,乔松径向生长与当年7月和9月最低温度的关系由不相关变为显著正相关,而与当年8月相对湿度和9月降水量的关系由不相关变为显著负相关。滑动相关分析表明,乔松径向生长与当年7—9月最低温度表现出较为稳定的正相关关系。在未来气候变暖的背景下,温度升高将促进乔松径向生长。.

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., β-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.
生物固氮是陆地生态系统氮素的重要来源,但不同森林生态系统土壤微生物固氮速率对氮沉降的响应仍不明确。本研究在亚热带黄山松林和罗浮栲林开展野外氮添加模拟大气氮沉降试验。以尿素为氮源,设置了3个氮添加水平:0(对照)、40(低氮)和80 kg N·hm-2·a-1 (高氮)。测定了表层(0～10 cm)土壤化学性质、微生物生物量碳、酶活性和nifH基因拷贝数,并利用15N标记法测定土壤微生物固氮速率。结果表明: 与对照相比,氮添加显著降低了黄山松林和罗浮栲林土壤微生物固氮速率,降幅分别为29%～33%和10%～18%。氮添加显著降低了两种林分土壤微生物氮获取酶(β-1,4-N-乙酰氨基转移酶)活性和nifH基因拷贝数。黄山松林土壤微生物固氮速率与可溶性有机碳含量存在显著正相关关系,而罗浮栲林土壤微生物固氮速率与铵态氮含量存在显著负相关关系。总之,黄山松林土壤微生物固氮功能对氮添加的响应比罗浮栲林更敏感,且影响土壤微生物固氮速率的因素在两种林分中存在差异。本研究可为氮沉降对森林生态系统生物固氮的影响提供见解,并为森林经营管理提供理论依据。.

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.
阐明亚热带湿润山地林区针阔混交林优势种水分来源的季节规律,解析共生植物水文生态位分配与竞争机制,探究植物水分利用对降水的响应,可为指导植被经营管理提供理论参考。本研究以庐山山区马尾松与栓皮栎混交林为对象,基于氢氧稳定同位素技术,分析降水、马尾松和栓皮栎木质部水及0～100 cm土壤水的δ2H和δ18O特征,采用MixSIAR模型、Levins指数和PS指数分别计算各水源的相对贡献率、马尾松与栓皮栎的水文生态位宽度和生态位重叠度。结果表明: 丰水期(3—7月)马尾松主要利用0～20和20～40 cm土壤水,栓皮栎主要利用20～40和40～60 cm土壤水,但在枯水期(8—9月)马尾松和栓皮栎分别转而利用40～60和60～80 cm土壤水,根系吸水深度增加。生长季早期(3—4月)和末期(9月)马尾松与栓皮栎水文生态位重叠度高,水分竞争激烈,生长季中期(5—8月)合理分配水源,水文生态位分离以满足高蒸腾需求。栓皮栎在降水事件前主要利用60～80和80～100 cm土壤水,降水后利用0～20和20～40 cm土壤水,但马尾松在降水事件前后均主要利用0～20和20～40 cm土壤水。综上,马尾松与栓皮栎的水分利用来源呈现“雨季浅,旱季深”的季节规律,能在生长旺季合理分配水源,根系吸水积极响应土壤水分动态,对极端降水的适应性强,具有较强的水源涵养能力。.

This study investigates whether red pine (Pinus densiflora Sieb. et Zucc.) bark extract (PBE) can alleviate diabetes and abnormal apoptosis signaling pathways in the hippocampus of streptozotocin (STZ)-induced diabetic Sprague-Dawley (SD) rats. Two dosages of PBE (15 and 30 mg/kg of body weight/day) were administered orally to STZ-induced diabetic SD rats for 20 days. Blood glucose level and body weight were measured once per week. After 20 days of oral administration of PBE, the rat hippocampus was collected, and the production of Akt, p-Akt, GSK-3β, p-GSK-3β, tau, p-tau, Bax, and Bcl-2 proteins were determined by western blot analysis. A decrease in blood glucose level and recovery of body weight were observed in PBE-treated diabetic rats. In the Akt/GSK-3β/tau signaling pathway, PBE inhibited diabetes-induced Akt inactivation, GSK-3β inactivation, and tau hyperphosphorylation. The protein production ratio of Bax/Bcl-2 was restored to the control group level. These results suggest that PBE, rich in phenolic compounds, can be used as a functional food ingredient to ameliorate neuronal apoptosis in diabetes mellitus.