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Copyright of Journal of Wildland Fire Science is the property of Journal of Wildland Fire Science Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Chinese fir (Cunninghamia lanceolata [Lamb.] Hook.) is a widely planted species of plantation forest in China, and heat treatment can improve its dimensional stability defects and improve its performance. The wood samples were heat-treated at various temperatures (160, 180, 200, and 220 °C) for 2 h. To clarify the effect of heat treatment on wood hygroscopicity, the equilibrium moisture content (EMC) was measured, the moisture adsorption and desorption rates were determined, the hygroscopic hysteresis was examined, and the Guggenheim, Anderson, and de Boer (GAB) model was fitted to the experimental data. The moisture absorption isotherms of all samples belonged to the Type II adsorption isotherm, but the shape of the desorption isotherm was more linear for heat-treated wood samples, especially when the heat treatment temperature was higher. According to the results analyzed with ANOVA, there were significant differences in equilibrium moisture content between the control samples and the heat-treated samples under the conditions of 30%, 60%, and 95% relative humidity (RH, p < 0.05), and the results of multiple comparisons were similar. The decrease in hygroscopicity was more pronounced in wood treated at higher temperatures. The EMC of the 160–220 °C heat-treated samples of the control samples was 14.00%, 22.37%, 28.95%, and 39.63% lower than that of the control sample at 95% RH. Under low RH conditions (30%), water is taken up mainly via monolayer sorption, and multilayer sorption gradually predominates over monolayer sorption with the increase in RH. The dynamic vapor sorption (DVS) analysis indicated that the heat-treated wood revealed an increase in isotherm hysteresis, which was due to the change in cell wall chemical components and microstructure caused by heat treatment. In addition, the effective specific surface area of wood samples decreased significantly after heat treatment, and the change trend was similar to that of equilibrium moisture content. [ABSTRACT FROM AUTHOR]

Background. The continuous establishment of Chinese fir (Cunninghamia lanceolata) plantations across multiple generations has led to the limited impact of soil phosphorus (P) on tree growth. This challenge poses a significant obstacle in maintaining the sustainable management of Chinese fir. Methods. To investigate the effects of Arbuscular mycorrhizal fungi (AMF) on the growth and physiological characteristics of Chinese fir under different P supply treatments. We conducted an indoor pot simulation experiment in the greenhouse of the Forestry College of Fujian Agriculture and Forestry University with one-and-half-year-old seedlings of Chinese fir from March 2019 to June 2019, with the two P level treatment groups included a normal P supply treatment (1.0 mmol L-1 KH2PO4, P1) and a no P supply treatment (0 mmol L-1 KH2PO4, P0). P0 and P1 were inoculated with Funneliformis mosseae (F.m) or Rhizophagus intraradices (R.i) or not inoculated with AMF treatment. The AMF colonization rate in the root system, seedling height (SH), root collar diameter (RCD) growth, chlorophyll (Chl) photosynthetic characteristics, enzyme activities, and endogenous hormone contents of Chinese fir were estimated. Results. The results showed that the colonization rate of F.m in the roots of Chinese fir seedlings was the highest at P0, up to 85.14%, which was 1.66 times that of P1. Under P0 and P1 treatment, root inoculation with either F.m or R.i promoted SH growth, the SH of R.i treatment was 1.38 times and 1.05 times that of F.m treatment, respectively. In the P1 treatment, root inoculation with either F.m or R.i inhibited RCD growth. R.i inhibitedRCDgrowth more aggressively than F.m. In the P0 treatment, root inoculation with F.m and R.i reduced the inhibitory effect of phosphorus deficiency on RCD. At this time, there was no significant difference in RCD between F.m, R.i and CK treatments (p < 0.05). AMF inoculation increased Fm, Fv, Fv/Fm, and Fv/Fo during the chlorophyll fluorescence response in the tested Chinese fir seedlings. Under the two phosphorus supply levels, the trend of Fv and Fm of Chinese fir seedlings in different treatment groups was F.m > R.i > CK. Under P0 treatment, The values of Fv were 235.86, 221.86 and 147.71, respectively. The values of Fm were 287.57, 275.71 and 201.57, respectively. It increased the antioxidant enzyme activity and reduced the leaf's malondialdehyde (MDA) content to a certain extent. Conclusion. It is concluded that AMF can enhance the photosynthetic capacity of the host, regulate the distribution of endogenous hormones in plants, and promote plant growth by increasing the activity of antioxidant enzymes. When the P supply is insufficient, AMF is more helpful to plants, and R.i is more effective than F.m in alleviating P starvation stress in Chinese fir. [ABSTRACT FROM AUTHOR]

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Achieving the accurate and efficient monitoring of forests at the tree level can provide detailed information for precise and scientific forest management. However, the detection of individual trees under planted forests characterized by dense distribution, serious overlap, and complicated background information is still a challenge. A new deep learning network, YOLO-DCAM, has been developed to effectively promote individual tree detection amidst complex scenes. The YOLO-DCAM is constructed by leveraging the YOLOv5 network as the basis and further enhancing the network's capability of extracting features by reasonably incorporating deformable convolutional layers into the backbone. Additionally, an efficient multi-scale attention module is integrated into the neck to enable the network to prioritize the tree crown features and reduce the interference of background information. The combination of these two modules can greatly enhance detection performance. The YOLO-DCAM achieved an impressive performance for the detection of Chinese fir instances within a comprehensive dataset comprising 978 images across four typical planted forest scenes, with model evaluation metrics of precision (96.1%), recall (93.0%), F1-score (94.5%), and AP@0.5 (97.3%), respectively. The comparative test showed that YOLO-DCAM has a good balance between model accuracy and efficiency compared with YOLOv5 and advanced detection models. Specifically, the precision increased by 2.6%, recall increased by 1.6%, F1-score increased by 2.1%, and AP@0.5 increased by 1.4% compared to YOLOv5. Across three supplementary plots, YOLO-DCAM consistently demonstrates strong robustness. These results illustrate the effectiveness of YOLO-DCAM for detecting individual trees in complex plantation environments. This study can serve as a reference for utilizing UAV-based RGB imagery to precisely detect individual trees, offering valuable implications for forest practical applications. [ABSTRACT FROM AUTHOR]

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Chinese fir is one of the most widely distributed and extensively planted timber species in China. Therefore, monitoring pests and diseases in Chinese fir plantations is directly related to national timber forest security and forest ecological security. This study aimed to identify appropriate vegetation indices for the early monitoring of pests and diseases in Chinese fir plantations. For this purpose, the researchers used an imaging spectrometer to capture hyperspectral images of both experimental and control groups. The experimental group consisted of Chinese fir trees with two sections of bark stripped off, while the control group consisted of healthy Chinese fir trees. The study then assessed the sensitivity of 11 vegetation indices to the physiological differences between the two groups using the Mann–Whitney U test. The results showed that both the green-to-red region spectral angle index (GRRSGI) and the red edge position index (REP) were able to monitor the difference as early as 16 days after damage. However, GRRSGI performs best in monitoring early death changes in Chinese fir trees because it is less affected by noise and is more stable. The green–red spectral area index (GRSAI) also had high stability, but the monitoring effect was slightly worse than that of GRRSGI and REP. Compared with other indices, GRRSGI and GRSAI can better exploit the advantages of hyperspectral data. [ABSTRACT FROM AUTHOR]

The Chinese fir (Cunninghamia lanceolata) is the largest tree species used for afforestation in China. The purpose of this study was to explore the effects of site quality, stand density, and tree species composition on the growth and yield of mixed Chinese fir forests and to build prediction models for their stand average DBH (diameter at breast height), average height, and volume. Using 430 plots of mixed Chinese fir forests in the Fujian Province of China, the optimal base models for predicting stand average DBH, average height, and volume were selected from the Schumacher, Korf, Logistic, Mitscherlich, and Richards equations. On this basis, the site class index (SCI), stand density index (SDI), and tree species composition coefficient (TSCC) were introduced to improve the model's performance, and the applicability of the different models was evaluated. The optimal base models for the average DBH, average height, and stand volume of mixed Chinese fir forests all used the Richards equation. The best fitting effect was obtained when the SCI was introduced into parameter a in the average height model, while the inclusion of the TSCC did not improve the model significantly. The fitting effects of the average DBH and stand volume models were both best in the form of y = a 1 S C I a 2 [ 1 − exp ⁡ (− b 1 S D I b 2 ) t ] c when the SCI and SDI were introduced. When the TSCC was further included, the fitting effects of the stand average DBH and volume models were significantly improved, with their R2 increased by 47.47% and 58.45%, respectively, compared to the base models. The optimal models developed in this study showed good applicability; the residuals were small and distributed uniformly. We found that the SCI had an impact on the maximum values of the stand average DBH, average height, and volume; the SDI was closely related to the growth rate of the diameter and volume, while the TSCC influenced the maximum values of the stand average DBH and volume. The model system established in this study can provide a reference for the harvest prediction and mixing ratio optimization of mixed Chinese fir forests. [ABSTRACT FROM AUTHOR]

To assess the alterations in soil properties resulting from the interplanting of broad-leaved tree species within coniferous forests, we conducted an investigation into soil quality in a mixed Chinese fir and broad-leaved forest, as well as in a Chinese fir pure forest (used as a control) in subtropical China. A total of 15 soil physicochemical properties were assessed across three soil depths—0–15 cm, 15–30 cm, and 30–45 cm—for the two forest types in the experimental study. Principal component analysis in conjunction with the Norm value was employed to create a minimal data set (MDS) for assessing six indicators, including bulk density (BD), total nitrogen (TN), total phosphate (TP), available potassium (AK), soil pH, and catalase (CAT). The soil quality index (SQI) was calculated for both forest types. The results demonstrated that following the interplanting of broad-leaved tree species in the Chinese fir forest, all soil physicochemical indicators were significantly improved compared to the control, and significant differences were also observed in the 0–15 cm and 15–30 cm soil layers (p < 0.05). The overall average of the SQI of the mixed forest (0.8523, 0.6636) was significantly higher than that of the control (0.4477, 0.3823) (p < 0.05) in the 0–15 cm and 15–30 cm soil layers, respectively. However, there was no significant difference in the SQI in the 30–45 cm soil layer (p > 0.05) between the two forest types. The results indicated that the SQI based on the minimal dataset (MDS) can reflect the SQI of the total dataset (TDS) when assessing soil quality in forests. Our research provides valuable scientific insights into soil science and an understanding of the relationships between soil properties, forest structure, and species composition in sustainable forest management. [ABSTRACT FROM AUTHOR]

Wood dyeing plays a crucial role in improving the aesthetic appeal of wood. To enhance the value of Chinese fir, this study used environmentally friendly mulberry pigment and ultrasonic technology to dye Chinese fir. A single-factor test was conducted to investigate the impact of ultrasonic power, dyeing temperature, dyeing time, and dye concentration on dye uptake and color difference. The results revealed that ultrasonic treatment significantly increased the dye uptake and color difference compared with conventional water bath dyeing methods. Based on the single-factor test, two indexes for the color fastness of washing and sun were added, and an orthogonal test was carried out. The range analysis results demonstrated that ultrasonic power had the greatest influence on dye uptake, while dye concentration showed the strongest impact on the color difference and color fastness in washing and sunlight. The dyeing process was optimized using the fuzzy comprehensive evaluation method, with the optimum parameters determined as follows: ultrasonic power of 340 W, dyeing temperature of 90 °C, dyeing time of 5 h, and dye concentration of 10%. Scanning electron microscopy revealed that ultrasound increased wood permeability and created cracks, providing attachment sites for dye molecules. Infrared analysis indicated that ultrasonic action enhanced the degradation of wood components, transforming them into smaller molecular substances and increasing the accessibility of dyes to wood. X-ray diffraction analysis demonstrated that ultrasonic action reduced wood crystallinity, facilitating the entry of dye molecules into Chinese fir fibers. In this study, we proposed for the first time to dye fir wood with mulberry pigment and use ultrasonic-assisted dyeing to investigate the effect of dyeing factors on the dyeing rate, color difference, and color fastness, which provides a valuable reference for natural pigment dyeing of Chinese fir. [ABSTRACT FROM AUTHOR]

Taking Chinese fir wood from plantation as the research object, three technological parameters including hot-pressing temperature (160, 180, 200 °C), hot-pressing time (20, 30, 40 min) and compression ratio (30%, 40%, 50%) were selected, and the compression densification modification test of Chinese fir was carried out by using the full factor experimental design. Based on the mechanical properties, microscopic morphology and crystallinity of wood, the effects of different processing parameters on wood properties were analyzed, and the densification process parameters of Chinese fir wood were optimized. The results showed that the properties of the densified wood prepared by Chinese fir were better under the technological conditions of hot pressing temperature of 180 °C, compression ratio of 50%, and pressing time of 40 min. The flexural strength, flexural modulus of elasticity, tensile strength, and hardness of the densified Chinese fir were 130.4 MPa, 12 338 MPa, 113.1 MPa and 1 631 N respectively, which increased by 112%, 113%, 44%, and 55% compared to the untreated wood. The scanning electron microscope observation showed that almost all the early wood cells were crushed, and there were regular folds along the direction of the wood ray, while some of the late wood cells were crushed, and most of them kept the original cavity structure. The hardness and elastic modulus of the cell wall of the densified wood were 16.7% and 45.7% higher than that of the untreated wood. The crystallinity of wood after compression treatment increased. The crystallinity of cellulose in the untreated wood and compressed Chinese fir was 46% and 53%, respectively. [ABSTRACT FROM AUTHOR]

Forest biomass dynamics are important indicators of forest productivity and carbon sinks, which are useful for evaluating forest ecological benefits and management options. Rapid and accurate methods for monitoring forest biomass would serve this purpose well. This study aimed at measuring aboveground biomass (AGB) and stand growth from tree crown parameters derived using unmanned aerial vehicle–light detection and ranging (UAV–LiDAR). We focused on 17-year-old Chinese fir plantations in a subtropical area in China and monitored them using UAV–LiDAR from February 2019 to February 2020. Two effective crown height (ECH) detection methods based on drone discrete point clouds were evaluated using ground survey data. Based on the evaluation results, the voxel method based on point cloud segmentation (root-mean-squared error (RMSE) = 0.62 m, relative RMSE (rRMSE) = 4.26%) was better than the tree crown boundary pixel sum method based on canopy height segmentation (RMSE = 1.26 m, rRMSE = 8.63%). The effective crown area (ECA) of an individual tree extracted using ECH was strongly correlated with the annual biomass growth (coefficient of determination (R2) = 0.47). The estimation of annual growth of individual tree crowns based on annual tree height increase (ΔH) derived from LiDAR was statistically significant (R2 = 0.33, p < 0.01). After adding the crown projection area or ECA, the model accuracy R2 increased to 0.57 or 0.63, respectively. As the scale increased to the plot level, the direct model with ECA (RMSE = 1.59 Mg∙ha−1∙a−1, rRMSE = 15.02%) had a better performance than the indirect model using tree height and crown diameter (RMSE = 1.81 Mg∙ha−1∙a−1, rRMSE = 17.10%). The mean annual growth rate of AGB per middle-aged Chinese fir tree was determined to be 8.45 kg∙a−1 using ECA and ΔH, and the plot-level growth rate was 11.47 Mg∙ha−1∙a−1. We conclude that the rapid and accurate monitoring of the annual growth of Chinese fir can be achieved based on multitemporal UAV–LiDAR and effective crown information. [ABSTRACT FROM AUTHOR]

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) is an important timber species native to southern China. While the single, unstructured breeding strategy was employed in the past three cycles of breeding, it is no longer adequate for managing a more advanced breeding population. In this study, we utilized restriction-site-associated DNA-sequencing (RAD-seq) to estimate the genetic diversity of breeding populations and phenotypic values or breeding values to estimate the genetic gain of hundred-grain weight, diameter at breast height, and wood basic density. To achieve a balance between genetic gain and genetic diversity, we combined the multiple populations and core-main populations methods to construct the fourth cycle breeding population. Finally, the fourth cycle breeding population was made up of a core population of 50 individuals with an inbreeding coefficient of ~0, and an additional main population of 183 individuals, with an effective population size of 108. Crossings made within and/or between different trait-targeted subpopulations could facilitate bidirectional gene flow between the core and main populations, depending on the breeding objectives. This structured breeding population of Chinese fir could aim for both short- and long-term genetic gains and has the potential to support the preservation of germplasm resources for future climate change. [ABSTRACT FROM AUTHOR]

Chinese fir (Cunninghamia lanceolata) is the main fast-growing timber species in China, and studies of its stand volume are important for evaluating the effectiveness of forest management. However, it is difficult to accurately estimate stand volume from the perspective of a single tree due to the mutual concealment among Chinese fir trees. Therefore, in this study, we propose a method for identifying different forms of Chinese fir. The specific idea is to realize the accurate identification of a single Chinese fir tree, two Chinese fir trees, and three Chinese fir trees, and construct their respective stand volume estimation models to obtain an estimate of the forest stand volume. The key results are as follows: (1) the overall accuracy of recognition of different forms of Chinese fir is 79%, and the construction of different forms of Chinese fir units is beneficial for identifying forest trees; (2) a multiunit volume equation for different forms of Chinese fir is constructed; (3) based on predictions obtained with the constructed stand volume model, the difference between the estimated stand volume and the measured stand volume is small, and the average accuracy reaches 89.19%; and (4) compared to traditional volume estimation methods based on individual tree scale, the research method in this study shows a significant improvement (about 9.96%) in overall accuracy. In summary, this method can weaken the influence of erroneous individual tree segmentation on the accuracy of stand volume estimation, and can greatly reduce the working time of single tree segmentation to achieve the fast and accurate estimation of fir plantation stand volume. [ABSTRACT FROM AUTHOR]

The aim of this study was to clarify the mechanism by which thinning alters stand structure and affects forest productivity by characterizing changes in stand quantitative maturity age, stand diameter distribution, structural heterogeneity, and forest productivity of Chinese fir plantations at different thinning times and intensities. Our findings provide insights into how the density of stands could be modified to enhance the yield and timber quality of Chinese fir plantations. The significance of differences in individual tree volume, stand volume, and timber merchantable volume was determined using one-way analysis of variance and post hoc Duncan tests. The stand quantitative maturity age was obtained using the Richards equation. The quantitative relationship between stand structure and productivity was determined using a generalized linear mixed model. We found that (1) the quantitative maturity age of Chinese fir plantations increased with thinning intensity, and the quantitative maturity age was much greater under commercial thinning than under pre-commercial thinning. (2) Individual tree volume and the proportion of medium-sized and large-sized timber merchantable volume increased with stand thinning intensity. Thinning promoted increases in stand diameter. pre-commercially thinned stands were dominated by medium-diameter trees when the quantitative maturity age was reached, whereas commercially thinned stands were dominated by largediameter trees. The living trees volume will decrease immediately after thinning, and then it will gradually increase with the age of the stand. When the stand volume included both living trees volume and thinned volume, thinned stands increased stand volume compared with unthinned stands. In precommercial thinning stands, the greater the intensity of thinning, the greater the increase in stand volume, and the opposite was true for commercial thinning. (3) Thinning also reduced heterogeneity in stand structure, which was lower after commercial thinning than after pre-commercial thinning. The productivity of pre-commercially thinned stands increased with thinning intensity, whereas that of commercially thinned stands decreased with thinning intensity. (4) The structural heterogeneity of pre-commercially and commercially thinned stands was negatively and positively correlated with forest productivity, respectively. In the Chinese fir plantations in the hilly terrain of the northern Chinese fir production area, when pre-commercial thinning was performed in the ninth year to a residual density of 1750 trees per hectare, the stand quantitative maturity age was reached in year 30, medium-sized timber accounted for 75.2% of all trees, and the stand volume was 667.9 m3 per hectare. This thinning strategy is favorable for producing medium-sized Chinese fir timber. When commercial thinning was performed in year 23, the optimal residual density was 400 trees per hectare. When the stand quantitative maturity age was reached in year 31, large-sized timber accounted for 76.6% of all trees, and the stand volume was 574.5m3 per hectare. This thinning strategy is favorable for producing large-sized Chinese fir timber. [ABSTRACT FROM AUTHOR]

The study aims at investigating the effect of exogenous plant hormones on the development of astringent seed in Chinese fir. Varying concentrations of exogenous gibberellin (GA3), indole acetic acid (IAA), and zeatin (ZT) were used on a sample that included different types of cones (four varieties with tight seed-scales, five varieties with splay seed-scales, and three varieties with reverse-wrapped scales); the sample was then studied for the occurrence of astringent seed. We found that the rate of astringent seed development was significantly reduced (P<0.05) with a higher concentration of GA3, and effectively reduced at a lower concentration of IAA (30-90 mg L-1). However, no obvious changes on astringent seed rate were detected when the concentration of IAA was raised to higher levels. With ZT treatment, no significant effect on astringent seed rate was observed in any of the varieties. It was also noted that cones with different types of seed-scales showed varying response to exogenous plant hormones. Under GA3, treatment, the probability of reduced astringent seed rate was observed in cones with reverse-wrapped seed-scales, followed by cones with splay seed-scales, and was the least in cones with tight seed-scales. IAA treatment showed no significant difference in the astringent seed rate among the three types of cones. ZT treatment (with concentration of 10 mg L-1) showed significant difference (P<0.05) in cones with reverse-wrapped and tight seed-scales only. The effect of the three exogenous plant hormones on top part of cones was very less as compared with the effect on the middle and base part of cones. [ABSTRACT FROM AUTHOR]

Forty-year-old Chinese fir (Cunninghamia lanceolata) plantations from 16 different provenances in China were selected as the study object to identify the differences in the phenotypes of the anatomical traits of their fine roots, and the characteristics of the responses of the functional traits of fine roots to different geographical environments were analyzed. The fine root diameter (FRD), stele diameter (SD), cortical thickness (CT), ratio of stele to root diameter (SDR), and ratio of cortex to cross-section (CCS) of the fine roots were measured. The differences in the anatomical traits of the fine roots of Chinese fir were compared at the distribution area level, and the correlation between these anatomical traits and environmental factors were examined. The findings revealed significant differences in the anatomical traits of the fine roots among the different provenances (P＜0.05). The FRD and SD of the fine roots of Chinese fir in different locations were ranked in the following descending order: northern belt＞east of middle belt＞center of middle belt＞west of middle belt＞southern belt. The FRD and SD of the fine roots of the trees in Shanghang (Fujian) and Xinyang (Henan) were larger than those in the other provenances, whereas those of the fine roots of the trees in Shangrao (Jiangxi) were the smallest. The CT of the fine roots of Chinese fir in the different areas decreased in the following order: northern belt＞west of middle belt＞east of middle belt＞center of middle belt＞southern belt. The CT of the fine roots of trees in Xinyang (Henan) was thinner than that in other provenances, whereas the fine roots of the trees in Shangrao (Jiangxi) and Luotian (Hubei) showed thicker cortical tissue. The results of redundancy analysis showed that the CT and CCS of the fine roots positively correlated with the soil phosphorus content and significantly negatively correlated with the soil nitrogen content (P＜0.05). The SDR of the fine roots showed a significant positive correlation with latitude (P＜0.05) and a significant negative correlation with soil phosphorus content (P＜0.05). The response characteristics of the anatomical traits of the fine roots of Chinese fir in different habitat conditions differed, indicating that the fine roots of Chinese fir produce variations in functional traits and implement various ecological strategies to adapt to the environmental conditions in different provenances. [ABSTRACT FROM AUTHOR]

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) is an important plantation tree species in China, and seed germination is a key step in forest tree cultivation. To reveal the gene expression network and molecular mechanisms in the germination of Chinese fir seeds, physiological indexes were measured and transcriptome and metabolome analyses were performed on Chinese fir seeds in four stages of germination (imbibition stage, preliminary stage, emergence stage, and germination stage). All six physiological indicators had significant differences at different developmental stages. In transcriptome and metabolome analysis, we identified a large number of differentially expressed genes (DEGs) and differentially accumulated metabolites (DAMs). Gene Ontology (GO) analysis showed a large number of DEGs associated with cell growth, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that DEGs were significantly enriched in the flavonoid biosynthesis, phenylpropanoid biosynthesis, and plant hormone signal transduction pathways. The KEGG enrichment results of DAMs were similar to those of DEGs. The joint analysis of DEGs and DAMs indicated that flavonoid biosynthesis and phenylpropanoid biosynthesis were the key pathways of Chinese fir seed germination. Our study revealed a number of key genes and key metabolites, laying the foundation for further studies on the gene regulatory network of Chinese fir seed germination. [ABSTRACT FROM AUTHOR]

The decomposition of carbon-rich litter in forest ecosystems is thought to regulate critical nutrient cycles, including biological N fixation. However, the dynamics of N fixation and its driving mechanisms during litter decomposition remain elusive. In the present study, we tracked N fixation rate (NFR), diazotrophic community characteristics and associated soil factors during the decomposition of Chinese fir and/or Schima superba leaf litter in a 60-day microcosm experiment. Soil NFR significantly increased as the litter addition and the incubation time, but it was not affected by litter types. Diazotrophic community interactions and key diazotroph species, identified by co-occurrence network, were changed as litter decomposition progressed. NFR was significantly correlated with the richness of putative key diazotrophs, and was mainly mediated by changes in soil NH4+-N, and key C fractions of organic C. Structural equation modeling further revealed that the intensification of soil N fixation functions during litter decomposition was mediated by complex diazotrophic interactions rather than community diversity. [ABSTRACT FROM AUTHOR]

Although foliar phosphorus application (FPA) is a fertilization method that can rapidly supplement nutrient elements in plants, it remains unclear whether it significantly affects the response strategy of roots under environmental stress. In this study, changes in plant growth, biomass allocation, and P use efficiency (PUE) of Chinese fir in different P environments were analyzed by FPA and root P application (RPA) treatments. The effects of FPA on P-foraging behavior of Chinese fir root system in P-deficient environment were then discussed. The root biomass with RPA was more significant at 0.03–0.25 mmol·L−1 P concentrations than that with FPA; however, the PUE was significantly reduced by 28.89–29.41 %. With an increase in the P application concentration, under the effect of FPA, the Chinese fir roots mainly reduced root proliferation by decreasing the tip number, surface area and volume but increasing in diameter, as well as the PUE of root, aboveground. As a result, the entire plant was improved. However, the degree of morphological adjustment of the root system was lower than that under RPA. In summary, both FPA and RPA can alleviate P starvation in Chinese fir to a certain extent, thereby improving PUE. Compared with RPA, FPA had a more significant impact on the behavior of Chinese fir roots in sensing and responding to soil P content, and the roots could more quickly sense changes in P content in the body. This mechanism provides valuable insights into the root response strategies of plants in P-deficient environments. • Under low P stress, significant differences existed in the effects of FPA (foliar phosphorus application) and RPA (root phosphorus application) on root P-foraging behavior of Chinese fir. • Chinese fir roots can quickly adjust their morphological by reducing tip number, surface area and volume, increasing the diameter to alleviate root proliferation under FPA treatment. • Phosphorus transfer pathway in Chinese fir was obviously changed under FPA treatment, leading to enhanced P use efficiency. [ABSTRACT FROM AUTHOR]

Non-structural carbohydrates (NSCs) are labile components in forest litter that can be released quickly at the early stage of litter decomposition and accelerate the metabolic turnover of soil microorganisms, which is essential for the formation of forest soil organic matter. Therefore, understanding the NSCs response mechanisms to forest litter at different altitudes is critical for understanding nutrient cycling in the forest soil under climate change conditions. In this study, we used the net bag decomposition method to observe the dynamics of NSCs release in Chinese fir topsoil and canopy litter at four altitudes for 360 days based on the climatic zone characteristics distributed vertically along the elevation of Wuyi Mountain. The release of NSCs in Chinese fir litter rise gradually with height increases during the decomposition. The difference of the cumulative release percentage of soluble sugar between different altitudes is more significant than that of starch. The response of the NSC content in different treatment groups at four altitudes are different. The release of NSCs in the leaf canopy litter is higher than that in the leaf topsoil litter. On the contrary, the release of NSCs in the mixture of leaf and twig topsoil litter is higher than that in the mixture of leaf and twig canopy litter. Taken together, this study is of great significance for a comprehensive understanding of the effect of climate change on NSCs during the decomposition of Chinese fir litter. [ABSTRACT FROM AUTHOR]

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) is one of the most important tree species for afforestation in China. First-, second-, and third-generation seed orchards of Chinese fir have been established successively, and rich germplasms have been accumulated in the process of genetic improvement. It is necessary to build a core collection of germplasms from Chinese fir seed orchards. In this work, we constructed core collections representing the genetic diversity of Chinese fir seed orchard resources based on SSR data. A total of 607 seed orchard materials from three generations were used to determine the best sampling method and intensity by comparing and analyzing nine methods for constructing core collections. Core Hunter's multi-strategy optimizes allele coverage and the distance criterion under a 30% sampling intensity (weight: A–NE, 0.7; CV, 0.3 and E–NE, 0.5; CV, 0.5), which is superior to other strategies and was selected as the best method. The two core collections (A–NE&CV73, E–NE&CV55) constructed contained all the alleles of the whole collection and effectively limited the homology in the core collections; each core collection contained 182 accessions. Our findings could contribute greatly towards improving the management of genetic resources in Chinese fir seed orchards and provide elite materials for future studies. [ABSTRACT FROM AUTHOR]

Accurate estimation of genetic relationships among breeding materials and their genetic diversity contributes to the optimal design of breeding programs. For Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), an important indigenous tree species in China, breeders have attempted to employ different molecular markers to address the genetic architecture of their target population, but the power of an advanced parent tree population with a complex pedigree relationship is still rather limited. In this study, a partly known pedigree map combined with marker-derived (SSRs and SNPs) information was implemented for the first time in the assessment of the genetic relatedness of a complex advanced parent tree population (n = 50) in Chinese fir. The bivariate analysis showed that relatedness coefficients between individuals based on SSRs were significantly correlated with SNPs (r = 0.690, p < 0.01). Moreover, the heatmap generated by the SSR-based coefficient matrix was largely consistent with that derived from the SNP-based matrix. Additionally, STRUCTURE and ADMIXTURE analyses based on the two markers showed an analogical genetic clustering result. When compared to the recorded pedigree information, the genetic relationships estimated by the two molecular markers were broadly parallel with pedigree relatedness. These results indicated that SSRs and SNPs can be used as effective tools to clarify genetic relationships when complete pedigree records are not available in Chinese fir. Based on the two markers, the present study revealed a relatively wide genetic variation (SSRs: PIC = 0.573; SNPs: PIC = 0.231) in the selected parent trees. This investigation provides important input into the progress of Chinese fir advanced-generation breeding. [ABSTRACT FROM AUTHOR]

The karst geo-ecosystems are fragile environments. The largest karst region in the world is located in southwestern China, within which the Guangxi province is one of the main areas. Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.), an evergreen species, is an important fast-growing timber tree in southern China. In the present study, we examined the genetic diversity and spatial genetic differentiation of Chinese fir in sampling localities around the karst landform region of Guangxi by genotyping 330 individuals from 11 sampling localities with 22 novel polymorphic microsatellite loci. High levels of gene flow have homogenized Chinese fir in Rongshui, Nandan, and Tiane sites, which are speculated to be the primary center of gene exchange and diversity for Chinese fir around the karst landform in Guangxi. Significant isolation by distance pattern was found among nine sampling localities. A moderate level of genetic differentiation (FST = 0.089, Dest = 0.139) between sampling localities was detected. Structure analysis divided Chinese fir into three subgroups (K = 3). With higher differentiation and less genetic variation than in the central population, marginal populations of Cangwu and Pubei were identified in the south of the karst landform. An effective conservation strategy focusing on the maintenance of genetic variation for marginal populations of the species was proposed. [ABSTRACT FROM AUTHOR]

Introduction: Available phosphorus (P) scarcity in the highly weathered soils of the subtropical forests in southern China is a serious concern. To ensure whether inoculation of arbuscular mycorrhizal fungi (AMF) with Chinese fir (Cunninghamia lanceolata) under low P stress conditions could promote its growth and P utilization capacity, an indoor pot simulation experiment was carried out with the different P supply treatments and Chinese fir seedlings as the tested material. Methods: The experiment had two P supply treatments, no P supply (P0, 0 mmol·L-1 KH2PO4) and normal P supply (P1, 1.0 mmol·L-1 KH2PO4). The seedling in each P supply treatment was inoculated with Glomus intraradices (Gi), a widespread species of AMF in the natural environment, and with no AMF inoculation as a control treatment (CK). The Gi infection rate in the root system, root cortex tissue dissolution rate, root morphological indexes and biomass, whole plant P use efficiency, and root P use efficiency of Chinese fir were determined under different treatment conditions. Results and Discussion: The results showed that P0 treatment significantly increased the Gi infection rate (p< 0.05). After inoculating AMF with different P supply treatments, the root cortex tissue dissolution rate was considerably enhanced. In contrast, the Chinese fir's root length and surface area were reduced; however, the root volume did not change significantly. The average root diameter in the P0 treatment and inoculated with AMF was significantly more prominent than in the uninoculated treatment (p< 0.05). The root biomass and root-to-shoot ratio at different P supply treatments were significantly higher in the Gi infection treatment than in the CK group. Under different P supply treatments, root inoculation with Gi promoted root P use efficiency and whole plant P use efficiency. In conclusion, low P stress condition promoted the colonization of AMF in the root system, increased the dissolution of root cortex tissue, root volume, and the average diameter, and promoted root biomass accumulation and P use efficiency. [ABSTRACT FROM AUTHOR]

The objectives of this study were to determine the differences in growth and developmental characteristics of the lateral branches of different Chinese fir strains and their correlation with endogenous hormones and to select Chinese fir strains suitable for the cultivation of knotless timber. Three-year-old Chinese fir of six different strains (Cunninghamia unicanaliculata, Chuizhisha, Yang 063, Hongxinsha, Yang 020, and Yang 061) were collected from a forest to serve as the research subjects. The developmental characteristics of the lateral branches of the different Chinese fir strains were investigated, and the endogenous hormone content of the lateral branches was measured. The results showed that the Chinese fir strains differed in under branch height, internode length of trunk (distance between two adjacent lateral branches), and number of lateral branches (number of lateral branches per round on the trunk). Among them, Yang 063 and Chuizhisha had the greatest under branch height; Chuizhisha and Yang 020 had the largest internode length; and Yang 020 and Yang 061 had the fewest lateral branches per round. The strains of Chinese fir also differed in the length, base diameter, and angle of lateral branches. The values of the lateral branch length and base diameter of the Chinese fir strains were ranked as follows: Yang 063＞ Yang 061＞ C. unicanaliculata＞ Hongxinsha＞ Yang 020＞ Chuizhisha; the values of the lateral branch angle of the Chinese fir strains were ranked as follows: Chuizhisha＞ Yang 020＞ Yang 061＞ Yang 063＞ Hongxinsha＞ C. unicanaliculata. Cytokinin, indoleacetic acid, and CCTK/CIAA contents in the lateral branches of the Chinese fir strains also differed; however, strigolactone was not detected in the lateral branches of Chinese fir. There were different degrees of correlation between the lateral branch growth indexes and endogenous hormone indexes of the different Chinese fir strains, endogenous hormones can affect the growth of lateral branches of plants, CTK promoted the growth of lateral branches of Chinese fir, and IAA inhibited the growth of lateral branches of Chinese fir, both of which have obvious antagonistic effects on the growth of lateral branches of Chinese fir. [ABSTRACT FROM AUTHOR]

Background and aims: Competitive vegetation in forest stands influence seedling growth by changing soil nutrient availability. However, studies on the effects of different weed control methods on seedling growth of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) are rare. Methods: We applied three weed control methods, comprising artificial sickle weeding (ASW), woody disc weeding (WDW), and nonwoven cloth weeding (nWCW), to explore their effect on growth of Chinese fir seedlings in a plantation in Jiangxi Province, China. Results: The weed control methods affected the shoot height and root-collar diameter of the seedlings. The contents of sugar, glucose, triglycerides, total cholesterol, and free fatty acids in newly developed leaves were increased after ASW and nWCW treatment, and were consistent with the expression of genes associated with glucokinase, sucrose phosphate synthase, and sucrose synthase. Weeding method influenced soil properties, including pH, moisture, total nitrogen (TN), ammonium-N, nitrate-N, total phosphorus, available phosphorus, and dissolved organic carbon contents. Moisture content was the main factor that influenced the soil bacterial community and leaf nutrition. High-throughput sequencing of the bacterial 16 S rRNA gene revealed that the weeding methods affected bacterial community structure. Specifically, compared with ASW and nWCW, WDW contributed to lower soil bacterial diversity, simpler bacterial interaction, and increase in pathogenic bacteria potential. Conclusions: The weeding methods differ in influence on soil bacterial community structure, soil properties, and plant growth, which are potentially useful to improve the growth of Chinese fir seedlings. ASW and nWCW strategies were recommended to be applied in the practice of weed control on seedling growth of Chinese fir. [ABSTRACT FROM AUTHOR]

Phosphorus (P) is among the most intractable constraints on plant fertility, particularly in acidic soils with high P fixation capacities. The effects of nutrient limitation and the adaptive strategies of plants in infertile soils are central topics in plant ecology. The development of tree cultivars with greater P use efficiency (PUE), defined as the ability of a tree to grow and be productive in soils with reduced P availability, would substantially improve forest development. The ability of plants to redistribute and transfer P across fractions determines their adaptability to P limitations. However, the mechanisms of P utilization and transport remain unknown in Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) from the perspective of P fraction distribution. In this study, we investigated the distribution and translocation patterns of exogenous P and different P fractions in the M1 Chinese fir, which was identified as exhibiting high P-deficient resistance ability and maintaining higher yield under low P stress relative to the average clones, using 32P tracking, which can accurately trace the migration pathways of exogenous P after plant absorption. We found that exogenous P in the roots was higher than in the stems or leaves under low-P conditions in which the amount of the exogenous P absorbed by M1 was significantly reduced. Under low-P conditions, the plants optimized P allocation, which led to higher PUE than under high-P conditions, with the highest PUE in the leaves, followed by the stems and roots. The M1 clone maintained a high ratio of soluble P (i.e., inorganic P and ester P) in its leaves and stems, which improved P mobility and recycling under the conditions of limited P. In the roots, the P fractions shifted from soluble inorganic P and ester P to insoluble P (i.e., nucleic P), but the total P concentration was relatively stable, which may ensure root growth and exogenous P absorption under the conditions of limited P. Our results confirm that the M1 Chinese fir reduces P demand, optimizes the allocation of P among P fractions, and increases PUE to maintain aboveground productivity in response to limited P conditions. [ABSTRACT FROM AUTHOR]

The thermal degradation behavior of naturally aging Chinese fir was investigated using a STA 449 thermal analyzer. The Chinese fir with different natural aging times showed different pyrolysis behaviors. The longer the natural aging time, the lower the initial pyrolysis temperature of Chinese fir. The results of activation energy estimated by Kissinger–Akahira–Sunose (KAS) method and Flynn–Wall–Ozawa (FWO) method are almost the same. However, with the increase in natural aging time, the activation energy of fir is increasing. The suitable pyrolysis reaction model of nature aging—10 Chinese fir was attributed to the "diffusion-Jander" (D3) model. Furthermore, a nth order reaction model serves for nature aging—70 and nature aging—100 Chinese fir reaction mechanism. [ABSTRACT FROM AUTHOR]

Plantation cultivation plays an important role in improving terrestrial ecosystem functions and services. Understanding the water-use patterns of major afforestation species is vital for formulating ecological restoration strategies and predicting the response of plantation to climate change. However, the impacts and drivers of forest types on water-use patterns of key tree species are poorly understood. Here, the combined methods of dual stable isotope of δD and δ18O and Bayesian mixed framework (MixSIAR) were employed to investigate the water-use patterns of Cunninghamia lanceolata (Chinese fir) in a monoculture, mixed forest with Cinnamomum camphora, and mixed forest with Alnus cremastogyne under different rainfall events in subtropical China. Furthermore, the relative contribution of different soil and plant factors to the water-use patterns of Chinese fir was quantified using a random forest model. Our results showed that Chinese fir in the mixed forests (with C. camphora or with A. cremastogyne) utilized less water from shallow soil compared to that in a monoculture but significantly improved the proportion of water absorbed from deep soil with the increase of 55.57%-64.90% and 68.99%-108.83% following moderate and heavy rainfall events, respectively. The most important factors contributing to the differences in water-use patterns of Chinese fir among monoculture and mixed forests were tree attributes (i.e., leaf biomass, eco-physiological regulation, and fine root biomass). These findings reveal that Chinese fir in mixed forests could optimize water-use patterns by adjusting plant properties for interspecific niche complementarity, improving the utilization of deep soil water. Overall, this study suggests that mixed-species plantations could improve water-use efficiency and reduce the sensitivity of tree species to precipitation change, indicating they are better able to cope with expected climate variability. [ABSTRACT FROM AUTHOR]

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Root branching and mycorrhizal symbioses are two major mechanisms for soil resource acquisition by trees. Understanding the relationship between these two mechanisms and their responses to varied environmental conditions is crucial for predicting the responses of foraging strategies of roots to environmental changes. This study was conducted in 11 Chinese fir (Cunninghamia lanceolata) plantations distributed in different environmental conditions in Subtropical China to assess the relationship between root tip traits related to nutrient foraging (branching ratio of 1st-order roots to 2nd-order roots, arbuscular mycorrhizal (AM) colonization) and their environmental variables, including mean annual precipitation (MAP), mean annual temperature (MAT), soil C, soil N, soil P, and soil pH. Root branching was more sensitive to environmental conditions than mycorrhizal symbioses. The branching ratio and AM colonization of Chinese fir were significantly related to several environmental variables. The branching ratios were positively correlated with MAT, but negatively correlated with soil C, soil N, and soil pH (P < 0.05), suggesting that harsh environmental conditions can promote absorptive root branching. To our surprise, the AM colonization of absorptive roots was not as sensitive to environmental factors as branching ratio. However, the AM colonization of absorptive roots was positively correlated with soil pH (P < 0.1), indicating that soil acidity controls mycorrhizal symbioses. Moreover, the branching ratio was significantly negatively correlated with AM colonization (P < 0.05). Our results confirmed that environmental conditions significantly regulate fine root branching and its mycorrhizal symbioses, but with different controlling variables. The negatively correlated relationship of branching ratio and AM colonization shows that environmental factors regulate absorptive root traits in different ways. [ABSTRACT FROM AUTHOR]

Copyright of China Forest Products Industry is the property of China Forest Products Industry Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Cross-laminated timber (CLT) has become a popular engineered wood product, mainly prepared from imported wood in China. More extensive research is needed to improve the local production of cross-laminated timber with fast-growing coniferous wood species. Chinese fir (Cunninghamia lanceolata) and one component polyurethane (1C-PUR) adhesive were selected to prepare CLT under different process parameters. International standard methods, scanning electron microscopy (SEM), optical microscopy (LM), confocal laser scanning microscopy (CLSM), and nanoindentation (NI) were applied. The bonding performance and failure mechanism of Chinese fir CLT were investigated and clarified. The results showed that the optimal gluing parameters for preparing CLT from Chinese fir wood were 160 g/m2 of glue, 0.9 MPa of pressure, and 180 minutes of pressing time. Failure of CLT made from Chinese fir lumber was mainly due to the shear failure of the vertical layer board. Cracks often appeared in the earlywood cells near the boundary between earlywood and latewood. The impact of adhesive penetration on the mechanical properties of the wood cell wall showed that adhesive penetration increased the elastic modulus of the cell wall at earlywood and latewood cells. • The optimal gluing parameters for preparing Chinese fir CLT were revealed. • The typical failure modes and structures of Chinese fir CLT were ascertained. • Microstructure and micromechanics on the bonding interface were investigated. [ABSTRACT FROM AUTHOR]

Successive planting and monoculture, as common forest management methods, are widely used globally, especially in Chinese fir plantations in the subtropical areas of southern China. Although soil fertility depletion and productivity decline caused by successive planting have been widely reported, the underlying mechanism is still ambiguous. In this study, the composition and diversity of soil microorganisms (rhizosphere and bulk soils) in Chinese fir seedlings exposed to successive planting soils (firstgeneration Chinese fir seedings, FCP. second-generation Chinese fir seedings, SCP. third-generation Chinese fir seedings, TCP) and broadleaf tree species soil (Phoebe zhennan S. Lee et F. N. Wei, CK) were examined with highthroughput sequencing technology. Our findings revealed that the diversity and richness of bacterial and fungal communities were remarkably reduced in TCP than FCP and SCP, and were remarkably different between FCP and SCP. At the phylum level, the fungi with greatest relative abundance were Basidiomycota (5.74-32.88%) and Ascomycota (57.63-87.38%), while the bacteria with the greatest relative abundance were Acidobacteria (23.16-31.17%) and Proteobacteria (24.71-29.32%) for all treatments in both soil types. Additionally, the relative abundance of some pathogens (Penicillium and Burkholderia) was significantly higher in TCP than in FCP and SCP, suggesting that the presence of pathogens is an important factor in increasing the incidence of soil-borne sickness. Moreover, changes in fungal and bacterial communities were predominantly driven by soil dissolved organic carbon (DOC), DOC/DON ratio (DOCN), NO3--N, microbial biomass carbon (MBC), and MBC/MBN ratio (MBCN). Overall, the long-term monoculture of Chinese fir promotes the microecological imbalance of rhizosphere and bulk soil, and remarkably reduced soil microbial community diversity. These results can provide a scientific support for the implementation of future management measures for fir plantations (e.g., fertilization, addition of microbial fungicides, and construction of mixed forests). [ABSTRACT FROM AUTHOR]

Rhizodeposition-derived carbon plays an important role in plant nutrient acquisition and soil carbon sequestration. However, how nitrogen deposition affects the distribution of rhizodeposition-derived carbon into aggregate classes (macrogagregates, microaggregates, and silt and clay) is unclear. We conducted a nitrogen addition experiment on Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) seedlings with continuously labeled 13CO2 for 120 days. Plant growth and the distribution of rhizodeposition-derived carbon into aggregate classes were assessed. Results showed that nitrogen additionconsiderably increased the ratio of aboveground to belowground biomass, but not aboveground and belowground biomass. Compared with the control, nitrogen addition resulted in a significantdecreaseby 52% inrhizodeposition-derived carbon in bulk soil.We found that more rhizodeposition-derived carbon was incorporated into macroaggregate, followed by microaggregate, and silt and clay regardless of nitrogen addition. The rhizodeposition-derived carbon was significantly decreased by 40% in macroaggregate, 60% in microaggregate, and 61% in silt and clay after nitrogen addition. Nitrogen addition and aggregate classes had no interactive effect on the rhizodeposition-derived carbon. Our results suggest that nitrogen deposition decreases the rhizodeposition of Chinese fir and its distributionin aggregate classes. [ABSTRACT FROM AUTHOR]

Copyright of Forest Research is the property of Forest Research Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aims: Our aim was to investigate how N addition affects arbuscular mycorrhizal fungal (AMF) growth in Chinese fir plantations. Methods: A Chinese fir plantation was treated with four different N addition treatments for one and half years starting in April 2019. AMF colonization, hyphal length density, community composition, and soil properties were under measurement. Results: N addition caused inapparent effects on AMF colonization, hyphal length density, and functional guilds (rhizophilic, edaphophilic, and ancestral). The predominant AMF species in the soil was Septoglomus viscosum. N addition altered AMF community and some rare species (e.g., Entrophospora infrequens) disappeared with N addition. Conclusion: AMF community structure was more sensitive to short-time N deposition than the symbiotic relationship between AMF and host plants. [ABSTRACT FROM AUTHOR]

Chinese fir [ Cunninghamia lanceolata (Lamb.) Hook] is an important evergreen coniferous tree species that is widely distributed in many southern provinces of China and has important economic value. The Chinese fir accounts for 1/4 and 1/3 of the total artificial forest area and stock volume, respectively. Red-heart Chinese fir is popular in the market because of its high density and red heartwood. The long-growth cycle hindered the breeding process of Chinese fir, while molecular marker-assisted breeding could accelerate it. However, Chinese fir, a perennial conifer species, has a large genome, which has not yet been published. In this study, the growth-related traits and secondary metabolite contents of red- and white-heart Chinese fir were measured and found to be different between them. There are extremely significant differences among growth-related traits (p < 0.001), but secondary metabolite contents have different correlations due to differences in chemical structure. Moreover, genotype effect analysis of the substantially correlated single nucleotide polymorphisms (SNPs) revealed that most of the loci related to each growth-related traits were different from each other, indicating a type specificity of the genes regulated different growth-related traits. Furthermore, among the loci related to secondary metabolite contents, nine loci associated with multiple metabolite phenotypes such as Marker21022_4, Marker21022_172, Marker24559_31, Marker27425_37, Marker20748_85, Marker18841_115, Marker18841_198, Marker65846_146, and Marker21486_163, suggesting the presence of pleiotropic genes. This study identified the potential SNP markers associated with secondary metabolites in Chinese fir, thus setting the basis for molecular marker-assisted selection. [ABSTRACT FROM AUTHOR]

Chinese fir (Cunninghamia lanceolata), which is an important coniferous tree species in China, is mainly planted in acidic soils with toxic aluminum (Al) levels. However, the consequences of Al toxicity and its resistance mechanism in Chinese fir remain largely uncharacterized. In this study, the Al-induced modification and possible role of cell wall in regulating Al tolerance in Chinese fir were investigated by using seedlings with contrasting Al tolerance, namely, Al-sensitive (YX02) and Al-resistant (YX01) genotypes. The results in present work showed that Al treatment resulted in a dose- and time-dependent inhibition of root growth and oxidative damage in both genotypes, but more in YX02 than in YX01. The severe oxidative damage observed in YX02 under Al stress was found to correlate with lower antioxidant enzyme activities as compared with YX01. The greater root growth inhibition observed in YX02 compared with YX01 was associated with a higher accumulation of Al in pectin and hemicllulose 1 (HC1) fraction because of the higher pectin and HC1 contents and the lower degree of pectin demethylation due to enhanced pectin methylesterase activity in YX02, which ultimately enhanced cell wall binding capacity for Al in YX02. Taken together, our results suggested that enhancement of antioxidant enzyme activities and cell wall modification-induced Al exclusion are the two mechanisms responsible for the Al tolerance of Chinese fir. [ABSTRACT FROM AUTHOR]

Red-heart Chinese fir (Cunninghamia lanceolata) has the advantages of high density and attractive color, making it popular in the market. To date, most studies about stems of woody plants have only been reported at the cytological level because of few living cells. In this study, the xylem was successfully partitioned into three effective sampling areas: sapwood, transition zone, and heartwood. Secondary metabolites, cell survival, and differentially expressed genes in the three sampling areas were, respectively, investigated. First, we identified the phenylpropanoid and flavonoid pathways closely related to color. Based on the chemical structure of secondary metabolites in pathways, two notable directions had been found. Luteolin's glycosylation products might be the key substances that regulated the color of heartwood in red-heart Chinese fir because of the 1,000-fold difference between red-heart and white-heart. We also found pinocembrin and pinobanksin in Chinese fir, which were rarely reported before. At the cytological level, we believed that the transition zone of red-heart Chinese fir was a critical region for color production because of the fewer living ray parenchyma cells. In addition, transcriptome and quantitative reverse transcription PCR (qRT-PCR) proved that genes regulating the entire phenylpropanoid pathway, upstream of the flavonoid pathway, and some glycosyltransferases were significantly upregulated in the transition zone of red-heart and then colored the heartwood by increasing metabolites. This is the first report on the color-related secondary metabolites regulated by differential genes in red-heart Chinese fir. This study will broaden our knowledge on the effects of metabolites on coloring woody plant xylems. [ABSTRACT FROM AUTHOR]

Soil extracellular enzymes play an important role in microbial functions and soil nutrient cycling in the context of increasing N deposition globally. This is particularly important for Chinese fir (Cunninghamia lanceolata) forests because of the decline in soil fertility induced by successive rotation. In this study, we aimed to determine the effects of simulated N deposition (N30: 30 kg ha−2 year−1; N60: 60 kg ha−2 year−1) and phosphorus addition (P20: 20 mg kg−1; P40: 40 mg kg−1) on the activity and stoichiometry of soil extracellular enzymes related to soil C, N, and P cycling in Chinese fir. The results showed that N addition alone increased the activity of soil β-1,4 glucosidase (BG) but decreased the activity of N -acetyl-β-d-glucosidase (NAG) and leucine aminopeptidase (LAP). N addition increased the ratios of soil enzymes, C:N and C:P, alleviated microbial N-limitation, and aggravated microbial C-limitation. P addition alone increased enzyme activity, and P40 addition increased the ratio of BG to soil microbial biomass carbon (MBC), and (NAG + LAP):MBC activity ratio, thereby aggravating C restriction. N and P co-addition significantly affected soil extracellular enzyme activity and stoichiometry. For instance, BG activity and BG:MBC activity ratio increased significantly under the N30 + P40 treatment, which intensified C-limitation. Soil pH was the main factor influencing enzyme activity, and these variables were positively correlated. The stoichiometric relationships of enzyme reactions were coupled with soil pH, total nitrogen (TN), and available phosphorus (AP). Our results indicate that changes in soil characteristics induced by N and P inputs influence the activities of soil microorganisms and result in changes in microbial resource acquisition strategies. This study provides useful insights into the development of management strategies to improve the productivity of Chinese fir forests under scenarios of increasing N deposition. [ABSTRACT FROM AUTHOR]

Screening Chinese fir (Cunninghamia lanceolata) clones with efficient calcium utilization is an effective strategy to maintain soil fertility and improve their productivity and adaptability to nutrient stress habitats. The calcium content of 17-year-old Chinese fir progenies was measured, and calcium accumulation, distribution, and utilization efficiency were compared to select clones that had high calcium utilization efficiency (CaUE). Significant differences in calcium content and accumulation were observed in different vegetative organs and clones. The highest average calcium content and accumulation were in needles, and the lowest averages were in stems and dead branches. Clone M43 had the highest total calcium accumulation, whereas clone M37 had the lowest. Among the tested clones, the CaUE of the whole tree for M23, M37, and M25 was significantly high, whereas that for M43 was the lowest. The CaUE of stems was the highest in M23 and lowest in M17. Thus, calcium content and accumulation in the vegetative organs are important factors affecting the CaUE of whole trees and stems of different Chinese fir clones. Considering the comprehensive CaUE and bioaccumulation in whole trees and stems, M23, M25, and M10 were clones with high CaUE that should be used in future studies on high-yield plantations. [ABSTRACT FROM AUTHOR]

The aim of this research is to investigate the interception effect of heavy metals, such as zinc (Zn), copper (Cu), lead (Pb), arsenic (As), and cadmium (Cd) in different ages of Chinese fir plantations. The study was conducted in 21-year-old (CF21, near mature stand) and 29-year-old (CF29, old stand) pure Chinese fir forest stands (CF) as well as a mixed coniferous and broad-leaved forest stand (MF) in Huitong from November 2016 to October 2017. The study results revealed the variation ranges of interception of Cu, Zn, Cd, As, and Pb by the research forest stands were respectively, 3.436–36.778 mg·m−2·month−1, 7.458–98.763 mg·m−2·month−1, 0.003–0.608 mg·m−2·month−1, 0.094–4.471 mg·m−2·month−1, and 1.251–23.141 mg·m−2·month−1. Compared with the different ages of CF, the average monthly interception of Cu, Zn, Cd, As, and Pb in CF21 were respectively, higher 6.0%, − 3.3%, 59.0%, 1.4%, and 3.4% than those in CF29. However, seasonal changes of that in CF of different ages were those in CF21 > in CF29 in summer and autumn, and those in CF21 < in CF29 in winter and spring. Compared in different forest types, the average monthly interception of Cu, Zn, Cd, As, and Pb in MF was respectively, higher 20.2%, 5.8%, 185.2%, 2.6%, and 12.3% than those in CF. Furthermore, the seasonal flux of heavy metal retention in the forest ecosystems was higher during winter and spring than in summer and in autumn. This study provided an important information regarding the dynamics of heavy metal interception in forest ecosystems. [ABSTRACT FROM AUTHOR]

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) is a major timber conifer species in southern China. In this study, we aimed to capture the rarely advanced phenomenon for selfing in this species and illustrated the underlying molecular mechanism, especially the hub gene-regulated networks and pathways, by global transcriptome analysis assays (RNA-Seq). Self-pollination trials revealed a wide variation of selfing effects among parents. Parent cx569 produced a selfed family with the best growth performance at the seedling stage. The growth-based extremely advanced (AD) (n=3) and depressed (DE) variants (n=3; different types) were then subjected to comparative RNA-Seq. The transcriptome data revealed more than 5000 differentially expressed genes (DEGs) for each comparison group (AD versus DE). Weighted gene co-expression network analysis (WGCNA) further identified more than 80 important DEGs that were significantly associated with growth traits in each comparison group. A subsequent enrichment analysis showed that the identified DEGs belonged to six main types, including xylem metabolism-related, sugar and energy metabolism-related, plant hormone signal transduction-related, stress response-related, cytochrome-related, and transcription factor genes. Ten hub genes represented by the ERF071, MYB-relate 305, WRKY6, WRKY31, PER3, LAC4, CESA8, CESA9, GID1, and PR1 genes were co-identified between AD and DE variants. These genes exhibited rather different expression patterns between AD and DE variants, especially of the transcription factor ERF071 gene that presented a low transcript level in the AD seedlings with only 4.45% activity compared to DE's. While, the plant hormone signal transduction GID1 gene was significantly upregulated in AD by about 20-fold when compared to DE's, and fold change of the lignin biosynthesis-related PER3, CESA9 and LAC4 gene expression parallel reached to 10--15 times in an upregulation pattern in AD seedlings. The set of hub gene-linked interaction networks and pathways revealed in this study may be responsible for the rarely advanced phenomenon for selfing at the seedling stage in Chinese fir. [ABSTRACT FROM AUTHOR]

Mechanical testing, microscopic image analysis, and X-ray diffraction were used to study the mechanical properties and their correlation with microstructure in three 20-year-old Chinese fir clones (Kailin 24, Kaihua 13, and Kaihua 3). The Chinese fir clones featured a modulus of rupture (MOR) of 52–59 MPa, a modulus of elasticity (MOE) of 10–11 GPa, and a compressive strength parallel to the grain of 31–34 MPa. Kaihua 13 and Kailin 24 had similar mechanical properties and were superior to Kaihua 3 among the tree clones. Radial variation indicated that their outerwood (rings 9–18) had better mechanical properties than their corewood (rings 3–7). Kaihua 13 with better mechanical properties had a larger ratio of cell wall to lumen than Kaihua 3 and Kailin 24. Outerwood with better mechanical properties also had a larger ratio of cell wall to lumen and a smaller microfibril angle compared to corewood with poor mechanical properties. Linear regression analysis also shows that for various clones and different radial positions in the same clone, anatomical structure parameters such as average cell wall thickness and the ratio of cell wall to lumen were positively correlated to their mechanical properties, while the microfibril angle was negatively correlated to mechanical properties. The two factors synergistically influence the mechanical properties of wood. [ABSTRACT FROM AUTHOR]

Background and Aims: Litter decomposition is a fundamental process of global nutrient cycling that affects soil gas emissions, such as nitrous oxide (N2O), which is a major greenhouse gas. However, it is unclear how mixing litter of different ages experiencing different nitrogen (N) and phosphorus (P) addition treatments affects litter decomposition rates and N2O emissions. This limits our understanding of the mechanisms whereby litter input affects soil N2O emissions.Here, we studied the effects of mixing litter of Chinese fir (Cunninghamia lanceolata) of different ages (1 year and 2 year) on soil N2O emissions and the underlying microbial mechanisms with a 100-day incubation experiment.We found that mixing litter of different ages significantly lowered decomposition rates and soil N2O emissions under the combination of high N and P addition. N addition directly increased soil N2O emission rates (r = 0.32) and indirectly increased them via increasing soil NO3--N (r = 0.12). P and high N addition slowed litter mass loss and had a negative non-additive effect on soil N2O emissions.This study provides new insights into the effects of mixing litter of different ages on decomposition and soil N2O emissions. In addition, it indicates that managing amounts and ratios of N and P additions in the context of stand age structure has the potential to mitigate soil GHG emissions.Methods: Litter decomposition is a fundamental process of global nutrient cycling that affects soil gas emissions, such as nitrous oxide (N2O), which is a major greenhouse gas. However, it is unclear how mixing litter of different ages experiencing different nitrogen (N) and phosphorus (P) addition treatments affects litter decomposition rates and N2O emissions. This limits our understanding of the mechanisms whereby litter input affects soil N2O emissions.Here, we studied the effects of mixing litter of Chinese fir (Cunninghamia lanceolata) of different ages (1 year and 2 year) on soil N2O emissions and the underlying microbial mechanisms with a 100-day incubation experiment.We found that mixing litter of different ages significantly lowered decomposition rates and soil N2O emissions under the combination of high N and P addition. N addition directly increased soil N2O emission rates (r = 0.32) and indirectly increased them via increasing soil NO3--N (r = 0.12). P and high N addition slowed litter mass loss and had a negative non-additive effect on soil N2O emissions.This study provides new insights into the effects of mixing litter of different ages on decomposition and soil N2O emissions. In addition, it indicates that managing amounts and ratios of N and P additions in the context of stand age structure has the potential to mitigate soil GHG emissions.Results: Litter decomposition is a fundamental process of global nutrient cycling that affects soil gas emissions, such as nitrous oxide (N2O), which is a major greenhouse gas. However, it is unclear how mixing litter of different ages experiencing different nitrogen (N) and phosphorus (P) addition treatments affects litter decomposition rates and N2O emissions. This limits our understanding of the mechanisms whereby litter input affects soil N2O emissions.Here, we studied the effects of mixing litter of Chinese fir (Cunninghamia lanceolata) of different ages (1 year and 2 year) on soil N2O emissions and the underlying microbial mechanisms with a 100-day incubation experiment.We found that mixing litter of different ages significantly lowered decomposition rates and soil N2O emissions under the combination of high N and P addition. N addition directly increased soil N2O emission rates (r = 0.32) and indirectly increased them via increasing soil NO3--N (r = 0.12). P and high N addition slowed litter mass loss and had a negative non-additive effect on soil N2O emissions.This study provides new insights into the effects of mixing litter of different ages on decomposition and soil N2O emissions. In addition, it indicates that managing amounts and ratios of N and P additions in the context of stand age structure has the potential to mitigate soil GHG emissions.Conclusions: Litter decomposition is a fundamental process of global nutrient cycling that affects soil gas emissions, such as nitrous oxide (N2O), which is a major greenhouse gas. However, it is unclear how mixing litter of different ages experiencing different nitrogen (N) and phosphorus (P) addition treatments affects litter decomposition rates and N2O emissions. This limits our understanding of the mechanisms whereby litter input affects soil N2O emissions.Here, we studied the effects of mixing litter of Chinese fir (Cunninghamia lanceolata) of different ages (1 year and 2 year) on soil N2O emissions and the underlying microbial mechanisms with a 100-day incubation experiment.We found that mixing litter of different ages significantly lowered decomposition rates and soil N2O emissions under the combination of high N and P addition. N addition directly increased soil N2O emission rates (r = 0.32) and indirectly increased them via increasing soil NO3--N (r = 0.12). P and high N addition slowed litter mass loss and had a negative non-additive effect on soil N2O emissions.This study provides new insights into the effects of mixing litter of different ages on decomposition and soil N2O emissions. In addition, it indicates that managing amounts and ratios of N and P additions in the context of stand age structure has the potential to mitigate soil GHG emissions. [ABSTRACT FROM AUTHOR]

Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) is a significant plantation species in South China. However, this plantation species is primarily utilized to produce low-value wood products. This study evaluated the feasibility of manufacturing cross-laminated timber using fast-grown small-diameter Chinese fir by investigating its bending performance and exploring the contribution of the lamination effect to the load capacity. Through bending tests and theoretical analysis, three different lay-ups with the same cross-laminated timber thickness (105 mm) but varying lamination thicknesses (35 mm, 21 mm, 15 mm) were examined. The results revealed that the 5-layer and 7-layer CLT, with the average bending strength of 37.4 MPa and 33.9 MPa, showed the significantly higher mean values than the 3-layer CLT (23.2 MPa). Moreover, the predicted ultimate loads and failure modes aligned with the experimental observations. Additionally, all mechanical criteria met the mechanical performance requirements for the 105 mm thick cross-laminated timber according to the ANSI/APA PRG 320 standard, except for bending stiffness. These findings provide valuable insights for improving the performance of Chinese fir cross-laminated timber made from small-diameter timber by optimizing lamination thickness and underscore the viability of producing cross-laminated timber using Chinese fir. [Display omitted] • Feasibility of Chinese fir for cross-laminated timber manufacturing is confirmed. • Appropriately reducing lamination thickness enhances bending performance. • The 5-layer cross-laminated timber shows superior bending performance. • Theoretical method adopted can predict load capacities and failure modes. [ABSTRACT FROM AUTHOR]

Lignin in biomass plays significant role in substitution of synthetic polymer and reduction of energy expenditure, and the lignin content was usually determined by wet chemical methods. However, the methods' heavy workload, low efficiency, huge consumption of chemicals and use of toxic reagents render them unsuitable for sustainable development and environmental protection. Chinese fir, a prevalent angiosperm tree, holds immense importance for various industries. Since our previous work found that Raman spectroscopy could accurately predict the lignin content in poplar, we propose that the lignin content of Chinese fir can be estimated by similar strategy. The results suggested that the peak at 2895 cm−1 is the optimal choice of internal standard peak and algorithm of XGBoost demonstrates the highest accuracy among all algorithms. Furthermore, transfer learning was successfully introduced to enhance the accuracy and robustness of the model. Ultimately, we report that a machine learning algorithm, combining transfer learning with XGBoost or LightGBM, offers an accurate, high-efficiency and environmental friendly method for predicting the lignin content of Chinese fir using Raman spectra. • Lignin content of Chinese fir is first accurate predicted based on its Raman signals. • Transfer learning enhances model quality, especially with limited data. • Combined algorithms and transfer learning achieve test R2 above 0.93 for highest prediction accuracy. [ABSTRACT FROM AUTHOR]

To give guidance for producing bamboo charcoal, chemical composition and cellulose crystallinity of moso bamboo with different natural stacking time of 1 and 2 months were determined. The co-pyrolysis characteristics of control or stacked bamboo and Chinese fir were investigated by thermogravimetric analysis. Results showed that natural stacking pretreatment changed chemical composition of moso bamboo and decreased cellulose crystallinity. The lignin content of B0, B1 and B2 was 27.56%, 30.70% and 25.36%, respectively. The crystallinity of cellulose was 40.15% of B0, 40.09% of B1 and 37.79% of B2. Even though pyrolysis process of all samples was similar, natural stacking pretreatment, mixing ratios and heating rates had a significant impact on their pyrolysis characteristics. But the synergistic interactions were not found during co-pyrolysis process. B1 had the highest char yield of 22.95%, which gradually increased with increase in B1 content of blends. 60%B1/40%W had the lowest activation energy (Ea) at all conversion rates, which was suggested to use as raw materials of charcoal. [ABSTRACT FROM AUTHOR]