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The slope aspect is an important environmental factor, which can indirectly change the acceptable solar radiation of forests. However, the mechanism of how this aspect changes the underground ecosystem and thus affects the growth of aboveground trees is not clear. In this study, Pinus yunnanensis plantation was taken as the research object, and the effects of soil and microbial characteristics on tree growth under different slope aspects and soil depths were systematically analyzed. The tree height (H) and ground diameter (GD) on the sunny slope were 7.64% and 8.69% higher than those on the shady slope. The soil pH, alkaline hydrolyzable nitrogen (AHN), available phosphorous (AP), available potassium (AK), total nitrogen (TN), total phosphorous (TP), and total potassium (TK) were significantly different between the different slope aspects. With the increase in soil depth, the content of organic matter (OM), AHN, AP, and AK decreased. There were significant differences in soil microbial diversity and community structure between the different slope aspects, but there was no significant difference among different soil depths. The abundance of Proteobacteria on a sunny slope was lower than that on a shady slope, and the richness of Firmicutes and Planctomycetota was higher than that in a shady slope. With the increase of soil depth, the richness of Proteobacteria increased, and the richness of Firmicutes and Planctomycetota decreased. The structural equation model showed that the influence of soil bacteria and fungi on soil characteristics was much greater than that on tree growth, and the influence of soil characteristics on tree growth was much greater than that of soil microorganisms. The slope aspect caused the difference of soil microorganisms, further affected the soil characteristics and led to the heterogeneity of aboveground forest growth. The insights gleaned from this study hold the potential to inform the formulation of customized management strategies, thereby enhancing resource utilization efficiency and fostering the vitality of forest ecosystems. Furthermore, this research offers theoretical underpinning for the targeted cultivation of coniferous plantations. [ABSTRACT FROM AUTHOR]

Phytohormones play a very important role in the regulation of plant growth and development. In order to explore the effects of different exogenous hormones on the sprout growth of Pinus yunnanensis seedlings after stumping, different concentrations of exogenous hormones indole-3-acetic acid (IAA) and 6-benzylaminopurine (6-BA) were sprayed on one-year-old P. yunnanensis seedlings as the research object. The experiment used a 3 × 3 regression design with two factors and three levels. The results showed that both IAA and 6-BA could promote the sprout emergence of P. yunnanensis. The sprout number of single 6-BA was higher than that of single IAA, but the effect of mixed spraying was better than that of single spraying. The optimal combination of hormones was IAA (150 mg·L−1) and 6-BA (200 mg·L−1). After hormone spraying, the average length of the sprouts of P. yunnanensis seedlings showed a trend of first fast and then slow increase over time. Therefore, spraying exogenous hormones IAA and 6-BA will have a certain effect on P. yunnanensis sprouts, and finding the appropriate hormone spraying concentration (IAA 150 mg·L−1 and 6-BA 200 mg·L−1) can maximize the sprout ability of P. yunnanensis seedlings and be more conducive to seedling sprout growth. [ABSTRACT FROM AUTHOR]

Cross breeding is an important way to innovate germplasm. However, the growth performance of hybrid offspring is difficult to predict. Pinus yunnanensis is an important tree species for both timber and industrial raw materials in southwest China, and its genetic degradation is a serious concern. To accelerate the breeding process and diversify the genetic resources, 16 interspecific crosses of P. yunnanensis × P. kesiya and 22 intraspecific crosses of P. yunnanensis were evaluated and selected based on the systematic analysis of nutritional and reproductive growth traits. The results indicated that the differences in traits between the different combinations were significant, suggesting that the interspecific and intraspecific hybrid offspring showed high genetic variation with potential for selection. The interspecific crosses were considerably better than the intraspecific crosses for all phenotypic traits, indicating that the distant hybridization had an advantage of heterosis. Compared with the open-pollinated progeny, the progeny of superior hybrid family significantly improved in nutritional growth traits, and declined in reproductive growth traits. The coefficients of phenotypic variation, genetic variation, family heritability and individual heritability for the phenotypic traits were higher than other Pinus, indicating that the traits were highly variable and under strong genetic control. Nutritional and reproductive growth traits could be selected independently. Five interspecific crosses and one intraspecific cross were selected using a combination of the membership function and an independent selection method. Our findings provided an important material basis and theoretical support for hybrid breeding and genetic improvement of Pinus. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis Franch. is a native species in southwestern China, characterized by high polymorphism. However, the environmental drivers of intraspecific variation in its functional traits remain poorly understood. In this study, we examined the relationships between five functional traits (bark thickness, tree height, leaf dry matter content, leaf length, and specific leaf area) and habitat conditions across 20 populations, representing three varieties: var. yunnanensis (the original variety), var. pygmaea , and var. tenuifolia. Our experiments aimed to determine whether the functional traits varied among the three varieties under different environmental conditions. As specific leaf area and leaf dry matter content showed no significant correlations with any environmental factors, we focused our analysis on the remaining three traits. Using random forest models, we assessed the significance of each environmental factor and found the following: Temperature seasonality was a key determinant of tree height; soil particle size (clay and sand) had the strongest influence on bark thickness; and for leaf length, precipitation during the driest quarter was the most important factor. These findings offer insights into the variation in functional traits of P. yunnanensis and enhance our understanding of its adaptation to diverse environments. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis has high economic and ecological value. The survival of P. yunnanensis has been greatly affected by global warming. This study examines the response of P. yunnanensis seedlings to drought stress and their recovery following rewatering, focusing on growth metrics and C:N:P stoichiometry. This experiment included the four following treatments: CK (water content was 90% ± 5%); LS (water content was 75% ± 5%); MS (water content was 60% ± 5%); and SS (water content was 45% ± 5%). This experiment also included a continuous drought period of 30 days followed by 7 days of rewatering. This study found that drought limited the growth of seedlings, and seedlings could recover rapidly from the damage caused by LS and MS treatments after rewatering, and the recovery of seedlings was greater following LS and MS treatments than following SS. After the drought, the C content in the leaves and stems of P. yunnanensis seedlings could recover to CK levels after rewatering. The N content of each organ and the P content of fine roots of P. yunnanensis seedlings showed an upward trend after rewatering. In summary, the growth of P. yunnanensis seedlings was significantly affected by drought stress, and the recovery mechanism of rewatering varied depending on the degree of drought. Combining the phenotypic plasticity index and principal component analysis, the stem biomass, thin root biomass, root/shoot ratio, leaf C:P, leaf N:P, leaf P, stem C:P, thin root N, thin root P, coarse root N, coarse root P, and coarse root C were the most important indexes for adaptation to drought and rewatering. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis is an endemic tree species in southwest China that has high ecological and economic benefits. Nowadays, global climate change is remarkable, the frequency of drought is increasing day by day, the distribution of rainfall is unbalanced, and even the phenomenon of alternating drought and flood has appeared, which is unfavorable to the growth of P. yunnanensis. We set up four treatments, namely normal water (CK), light drought (LD), moderate drought (MD), and severe drought (SD), and water content was controlled by the weighing method. After continuous drought for 30 days, re-watering was performed for 7 days. The stoichiometric characteristics of non-structural carbohydrates (NSC), soluble sugars (SS), and starch (ST), as well as carbon (C), nitrogen (N), and phosphorus (P), in various organs of P. yunnanensis seedlings were measured. The results revealed significant effects of re-watering on NSC and its components in P. yunnanensis seedlings. The SS and NSC contents in the leaves of P. yunnanensis seedlings treated with SD were significantly higher than those of the control. The C content in the leaves and stems of P. yunnanensis seedlings recovered to the CK level after re-watering under different drought degrees. The contents of N in different organs and P in the fine roots of P. yunnanensis seedlings increased after re-watering with the LD, MD, and SD treatments, while the C/N ratio decreased. In summary, the recovery mechanism of P. yunnanensis seedlings to re-watering varied with the drought degree. The contents and ratios of NSC, C, N, and P in different organs of P. yunnanensis seedlings were significantly affected by re-watering. Combining the phenotypic plasticity index and PCA results, seedlings of P. yunnanensis adapted to drought re-watering by adjusting leaf NSC, leaf P, stem SS/ST, fine root ST, and fine root NSC. [ABSTRACT FROM AUTHOR]

Identifying the key climate variables affecting optical saturation values (OSVs) in forest aboveground biomass (AGB) estimation using optical remote sensing is crucial for analyzing OSV changes. This can improve AGB estimation accuracy by addressing the uncertainties associated with optical saturation. In this study, Pinus yunnanensis forests and Landsat 8 OLI imagery from Yunnan were used as case studies to explain this issue. The spherical model was applied to determine the OSVs using specific spectral bands (Blue, Green, Red, Near-Infrared (NIR), and Short-Wave Infrared Band 2 (SWIR2)) derived from Landsat 8 OLI imagery. Canonical correlation analysis (CCA) uncovered the intricate relationships between climatic variables and OSV variations. The results reveal the following: (1) All Landsat 8 OLI spectral bands showed a negative correlation with the Pinus yunnanensis forest AGB, with OSVs ranging from 104.42 t/ha to 209.11 t/ha, peaking in the southwestern region and declining to the lowest levels in the southeastern region. (2) CCA effectively explained 93.2% of the OSV variations, identifying annual mean temperature (AMT) as the most influential climatic factor. Additionally, the mean temperature of the wettest quarter (MTQ) and annual precipitation (ANP) were significant secondary determinants, with higher OSV values observed in warmer, more humid areas. These findings offer important insights into climate-driven OSV variations, reducing uncertainty in forest AGB estimation and enhancing the precision of AGB estimations in future research. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis (Franch), a species endemic to southwestern China, provides significant ecological and economic benefits. The quality of afforestation can be enhanced by promoting high-quality sprout growth. This study analyzed the effects of six fertilization treatments following top pruning: T1 (N: 0 g/plant−1; P: 0 g/plant−1), T2 (N: 0 g/plant−1; P: 2 g/plant−1), T3 (N: 0 g/plant−1; P: 4 g/plant−1), T4 (N: 0.6 g/plant−1; P: 0 g/plant−1), T5 (N: 0.6 g/plant−1; P: 2 g/plant−1), and T6 (N: 0.6 g/plant−1; P: 4 g/plant−1). The accumulation and allocation of aboveground biomass in roots, stems, and leaves of P. yunnanensis were measured, as well as changes in biomass per plant at 90 days (early stage), 180 days (middle stage), and 270 days (late stage) post-fertilization. At 90 days, root biomass accumulation in T3 was significantly higher, by 13.31%, compared to that in T1 (p < 0.05). The growth rates of stem and plant biomass followed the order T6 > T1 > T3 > T5 > T4 > T2. The biomass of sprouts and individual plants exhibited allometric growth under T1, T5, and T6 treatments. At 180 days, needle biomass allocation in T1 and T4 increased by 7.47% and 8.6%, respectively, compared to 90 days. Combined nitrogen–phosphorus fertilization significantly influenced aboveground biomass allocation, promoting growth more effectively than other treatments. By 270 days, the stem and individual biomass in T2 and T3 treatments showed significant differences (p < 0.01) compared to other treatments. Overall, root, stem, and sprouts were primarily influenced by phosphorus fertilization, while nitrogen fertilization notably promoted needle and leaf growth in later stages. The aboveground components were more affected by phosphorus fertilization. The combination of nitrogen and phosphorus fertilizers enhanced early-stage stem and sprouts, as well as late-stage root development. [ABSTRACT FROM AUTHOR]

Appropriate nitrogen (N) and phosphorus (P) fertilization is critical for plant growth and production. Pinus yunnanensis, a silvicultural tree in southwestern China, faces economic and ecological limitations due to nutrient deficiency in the soils in its distribution areas. The slow growth of this species during the seedling stage exacerbates these problems. Therefore, it is important to realize the regulating effects of N and P proportioning fertilization on seedling growth to enhance nutrient-use efficiency. In this study, variations in morphological, physiological, and biochemical characteristics of seedlings were analyzed under nine treatments of NP proportioning in an open nursery using a regression design. Growth in height and basal diameter increased and showed an approximate tendency in all treatments. The maximum biomass accumulation was observed at 480 d after treatment in roots of T5 (14.714 g) (application N 0.4 g·per−1 and P 3 g·per−1), stems of T5 (12.654 g), leaves of T9 (24.261 g) (application N 0.8 g·per−1 and P 6 g·per−1), aboveground parts of T9 (35.402 g) and individuals of T5 (49 g). The total chlorophyll content peaked in the leaves at 120 d and was correlated with the peak levels of N, P, and K in leaves. The content and reserves of nutrient elements in the organs of seedlings subjected to NP proportioning were significantly higher than those in unfertilized seedlings. Analysis of nutrient utilization efficiency revealed that T5 demonstrated superior seedling growth performance. Appropriate fertilization dosage of N and P for P. yunnanensis seedlings in this study was 0.32 g·per−1–0.58 g·per−1 and 3.02 g·per−1–4.95 g·per−1 respectively, using path analysis and regression equation. Transcriptomic sequencing revealed that there were 2,301 DEGs between T5 and T1 (control), which were involved in the uptake and assimilation of nutrients, biosynthesis of phytohormones and secondary metabolites, and photosynthesis. Additionally, the abundance of genes involved in cell division and proliferation, cellulose biosynthesis, and cell wall extension were dramatically upregulated, which potentially correlated with enhanced seedling growth. In conclusion, this study provides comprehensive information on the response of seedlings to varying proportions of N and P and may promote the growth of P. yunnanensis seedlings by optimizing the proportion of N and P in fertilizers.

Pinus yunnanensis Franch. is a native species in southwestern China, characterized by high polymorphism. However, the environmental drivers of intraspecific variation in its functional traits remain poorly understood. In this study, we examined the relationships between five functional traits (bark thickness, tree height, leaf dry matter content, leaf length, and specific leaf area) and habitat conditions across 20 populations, representing three varieties: var. yunnanensis (the original variety), var. pygmaea, and var. tenuifolia. Our experiments aimed to determine whether the functional traits varied among the three varieties under different environmental conditions. As specific leaf area and leaf dry matter content showed no significant correlations with any environmental factors, we focused our analysis on the remaining three traits. Using random forest models, we assessed the significance of each environmental factor and found the following: Temperature seasonality was a key determinant of tree height; soil particle size (clay and sand) had the strongest influence on bark thickness; and for leaf length, precipitation during the driest quarter was the most important factor. These findings offer insights into the variation in functional traits of P. yunnanensis and enhance our understanding of its adaptation to diverse environments.

Abstract [Objective] This study aims to investigate the effects of drought stress on the distribution of carbon (C), nitrogen (N), and phosphorus (P) elements and stoichiometry in organs of Pinus yunnanensis seedlings, and to provide a theoretical basis for water management in the cultivation of P . yunnanensis. [Methods] The contents of C, N, and P in organs of 1-year-old P . yunnanensis seedlings under drought stress were determined by potted water control method and four drought treatments. [Results] (1) Compared with the appropriate water treatment, the C content in leaves, stems, and fine roots of P . yunnanensis seedlings was decreased under drought stress, but was increased in coarse roots. N content was decreased in coarse roots and increased in fine roots. P content was increased in leaves and decreased in stems. (2) The variation coefficient of element content was P>N>C. The contents of C and N showed the greatest variability in fine roots. The variability of P content was the highest in leaves and the lowest in coarse roots. (3) There was a significant negative correlation between N content and coarse roots, a significant positive correlation between stems and fine roots, and a significant positive correlation between N and P contents in stems and coarse roots. [Conclusion] Under drought stress, growth of P . yunnanensis seedlings is restricted by N elements, and the utilization efficiency of N and P is increased. The overall variability of C, N, and P content in coarse and fine roots is higher than leaves and stems. The root system is more sensitive to changes in soil water status.

Abstract 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.

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. [ABSTRACT FROM AUTHOR]

[Objective] The paper aimed to comprehend the expression characteristics of cinnamyl alcohol dehydrogenase from Pinus yunnanensis and its involvement in lignin biosynthesis. (Method) The relative concentrations of 18 specific small molecules within the lignin pathway were assessed in the stems, buds, and needles of one-year-old P. yunnanensis. Additionally, the CAD genes of P. yunnanensis were identified, cloned and bioinformatics analyzed by comprehensive analysis of transcriptome data. RT-qPCR was employed to examine their expression patterns across various tissues. (Result] The findings revealed that among the 18 lignin pathway molecules, the relative con- tent of 5-0-caffeoylshikimic acid, 5-0-p-coumaroyl shikimic acid, and caffeic acid were higher in the buds, while the relative content of 3- O-p-coumaroyl quinic acid, p-coumaric acid, ferulic acid, coniferylaldehyde, L-phenylalanine, coniferyl alcohol, p-coumaryl alcohol, L- (-)-tyrosine, sinapinaldehyde were higher in the stems. In addition, the relative content of coniferin, p-coumaraldehyde, caffeic aldehyde, and syringin were higher in the needles. Four members of the CAD family were screened from the transcriptome of P. yunnanensis, and phylogenetic analysis showed that PyCAD-3 of P. yunnanensis was homologous to AtCADI, and PyCAD-1, PyCAD-2 and PyCAD-4 were closely related to CAD of Pinus, AtCAD4 and ALCAD5. The results of correlation analysis showed that the PyCAD-1 and PyCAD-2 were closely related to small molecules in the lignin pathway upstream and downstream. The open reading frame of PyCAD-1 and PyCAD-2 was 570 and 1083 bp, respectively, and the molecular weights of PyCAD-1 and PyCAD-2 were 20.38 and 39.30 kDa, respectively. The results of RT-qPCR showed that the relative expression of PyCAD-1 was the highest in bud and tender stem, and PyCAD-2 was the highest in tender stem. [Conclusion] It is speculated that PyCAD-2 may be directly involved in lignin biosynthesis, while PyCAD-1 may have some functional redundancy. The study provides a theoretical basis for studying CAD genes family and genes related to the lignin metabolism pathway of P. yunnanensis. [ABSTRACT FROM AUTHOR]

Non-structural carbohydrates (NSC) are an important "buffer" for maintaining plant physiological functions under drought conditions; however, our understanding of the dynamics of NSC at the organ level during sustained drought of varying intensities and re-watering remains poor. In this study, two-year-old Pinus yunnanensis seedlings were subjected to drought and re-watering trials. Plants were subjected to three drought intensities (light drought, moderate drought, and severe drought) as well as control conditions (suitable moisture) for 51 days, including 30 days of drought followed by 21 days of re-watering for drought-treated seedlings, to study the dynamics of NSC in the leaves, stems, coarse roots, and fine roots. Changes in the distribution of NSC concentrations in the organ of P. yunnanensis seedlings under drought stress varied; in the early drought stages, the drought resistance of P. yunnanensis seedlings was enhanced by increasing soluble sugar concentrations; in later stages of drought, the stored starch in organs, stems, and coarse roots was consumed. Drought inhibited the growth of P. yunnanensis seedlings, but the maximum limit of drought tolerance was not reached under the different drought treatments after 30 days. P. yunnanensis seedlings in all treatment groups resumed growth after re-watering, and the growth of seedlings was actually promoted during re-watering in the moderate drought treatment group, indicating that drought induced the compensatory growth of seedlings. The growth of P. yunnanensis seedlings during re-watering was inhibited in the severe drought treatment group, and NSC continued to be regulated in seedlings in this group. Given that P. yunnanensis seedlings maintain growth through the consumption of coarse root starch in the late stages of drought, seedlings with a larger root-to-shoot ratio should be selected for cultivation in actual production. Based on our findings, exposure to moderate drought stress can enhance the drought tolerance of P. yunnanensis seedlings and promote the compensatory growth of seedlings. [ABSTRACT FROM AUTHOR]

The relationship between plants and the environment is the foundation of plant community composition. It is urgent to clarify the distribution pattern and influencing factors of community biodiversity, especially the driving patterns of environmental factors under the conditions of invasive alien species. In this study, we investigated the effects of various environmental factors, especially altitude and Ageratina adenophora invasion, on forest community differentiation in Pinus yunnanensis forest in Panxi region, providing a strong theoretical basis for forest management and natural resource protection in this area. Based on the field survey data of 40 sample sites, a total of 18 environmental factors, including climate, terrain, soil and biology are selected, which may affect Pinus yunnanensis community. The methods of Two-way indicator species analysis (TWINSPAN), Redundancy analysis and Locally weighted linear regression are adopted by quantitative ecology. The effects of environmental factors on forest community type, species distribution pattern and species diversity were discussed. The results show that: (1) The Pinus yunnanensis community was divided into 4 types by TWINSPAN. (2) Altitude, annual mean temperature, soil pH, soil total phosphorus, Ageratina adenophora invasion were significantly correlated with forest community types and species distribution. (3) With the increase in altitude, the species diversity of Pinus yunnanensis community decreased firstly and then increased, and reached its lowest point at about 1800–2000 m a.s.l. With the increase in Ageratina adenophora invasion, the species diversity index of the community showed a downward trend. (4) The species diversity index of the tree layer was negatively correlated with the altitude. The species diversity index of herbaceous layer was negatively correlated with the Ageratina adenophora invasion intensity. Environmental factors had little influence on the species diversity index of shrub layer. It is suggested that the next research focus should be on setting up experimental areas for the invasion area of Ageratina adenophora, exploring scientific and effective removal methods, strengthening the restoration research and demonstration construction of the invaded ecosystem. By simulating and reconstructing the historical distribution dynamics of Ageratina adenophora, analyzing its diffusion trend and environmental interpretation, predicting the suitable areas in China under the background of climate change. We will conduct long-term monitoring and risk assessment of invaded and potential spread areas, and formulate and implement prevention and control policies. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) 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.)

Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) 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.)

Phenylalanine ammonia lyase (PAL) is the rate-limiting and pivotal enzyme of the general phenylpropanoid pathway, but few reports have been found on PAL genes in Pinus yunnanensis. In the present study, three PAL genes were cloned and identified from P. yunnanensis seedlings for the first time, namely, PyPAL-1, PyPAL-2, and PyPAL-3. Our results indicated that the open-reading frames of PyPAL genes were 2184, 2157, and 2385 bp. Phylogenetic tree analysis revealed that PyPALs have high homology with other known PAL genes in other plants. In vitro enzymatic analysis showed that all three PyPAL recombinant proteins could catalyze the deamination of L-phenylalanine to form trans-cinnamic acid, but only PAL1 and PAL2 can catalyze the conversion of L-tyrosine to ρ-coumaric acid. Three PyPAL genes were expressed in different tissues in 1-year-old P. yunnanensis, and such genes had different expression patterns. This study lays a foundation for further understanding of the biosynthesis of secondary metabolites in P. yunnanensis. [ABSTRACT FROM AUTHOR]

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.)

Abstract [Objective] This study aims to construct a reliable core germplasm of Pinus yunnanensis for timber wood, to enhance its breeding, development, and utilization, and to solve the problems of its distribution, high preservation cost, preservation difficulties, and hence promoting its utilization. [Methods] The original germplasm was derived from 780 sample plants of 26 natural P . yunnanensis populations, with 18 phenotypic traits serving as the original data. The study employed two distinct construction strategies, geographical perspective and an enhanced minimum distance stepwise sampling method, to assess the representativeness of the core germplasm constructed with different strategies. [Results] (1) The genetic diversity index of the germplasm subset, including 219 samples constructed from a geographical perspective, was significantly lower than that of the four subsets constructed by the enhanced minimum distance stepwise sampling method; however, it was slightly higher than the original germplasm. The germplasm subset and the original germplasm had MD value of 3.921%, VD value of 83.333%, CR value of 82.207%, and VR value of 99.482%. A principal component analysis of the original germplasm quality and the germplasm subset 18 traits revealed cumulative contribution rates of 79.376% and 82.163%, respectively; the germplasm subset distribution was relatively concentrated. (2) The enhanced minimum distance stepwise sampling method was utilized to construct four seed subsets with sampling ratios of 10%, 20%, 30%, and 40%. Among these, the germplasm subset with a 20% sampling ratio proved to be the most effective, with a diversity index significantly higher than the original germplasm. The germplasm subset with 20% sampling proportion and the original germplasm had MD value of 6.363%, VD value of 83.333%, CR value of 91.099%, and VR value of 124.448%. A principal component analysis was conducted on a germplasm subset with a 20% sampling proportion, revealing a cumulative contribution rate of 83.539%, exceeding that of the original germplasm. The germplasm subset distribution range encompassed the entire sampling range. [Conclusion] Construction using different methods yield varying degrees of genetic diversity from the original germplasm, while both construction methods could represent the core collection of P . yunnanensis germplasm resources. The germplasm subset derived from the geographical perspective offers more advantages in collection, preservation, and renewal of these resources, which provided a method for the preservation of P . yunnanensis germplasm resources and the breeding of superior germplasm, offering a novel reference method for the construction of other germplasm resources.

Pinus yunnanensis (Franch), a species endemic to southwestern China, provides significant ecological and economic benefits. The quality of afforestation can be enhanced by promoting high-quality sprout growth. This study analyzed the effects of six fertilization treatments following top pruning: T1 (N: 0 g/plant−1; P: 0 g/plant−1), T2 (N: 0 g/plant−1; P: 2 g/plant−1), T3 (N: 0 g/plant−1; P: 4 g/plant−1), T4 (N: 0.6 g/plant−1; P: 0 g/plant−1), T5 (N: 0.6 g/plant−1; P: 2 g/plant−1), and T6 (N: 0.6 g/plant−1; P: 4 g/plant−1). The accumulation and allocation of aboveground biomass in roots, stems, and leaves of P. yunnanensis were measured, as well as changes in biomass per plant at 90 days (early stage), 180 days (middle stage), and 270 days (late stage) post-fertilization. At 90 days, root biomass accumulation in T3 was significantly higher, by 13.31%, compared to that in T1 (p < 0.05). The growth rates of stem and plant biomass followed the order T6 > T1 > T3 > T5 > T4 > T2. The biomass of sprouts and individual plants exhibited allometric growth under T1, T5, and T6 treatments. At 180 days, needle biomass allocation in T1 and T4 increased by 7.47% and 8.6%, respectively, compared to 90 days. Combined nitrogen–phosphorus fertilization significantly influenced aboveground biomass allocation, promoting growth more effectively than other treatments. By 270 days, the stem and individual biomass in T2 and T3 treatments showed significant differences (p < 0.01) compared to other treatments. Overall, root, stem, and sprouts were primarily influenced by phosphorus fertilization, while nitrogen fertilization notably promoted needle and leaf growth in later stages. The aboveground components were more affected by phosphorus fertilization. The combination of nitrogen and phosphorus fertilizers enhanced early-stage stem and sprouts, as well as late-stage root development.

Identifying the key climate variables affecting optical saturation values (OSVs) in forest aboveground biomass (AGB) estimation using optical remote sensing is crucial for analyzing OSV changes. This can improve AGB estimation accuracy by addressing the uncertainties associated with optical saturation. In this study, Pinus yunnanensis forests and Landsat 8 OLI imagery from Yunnan were used as case studies to explain this issue. The spherical model was applied to determine the OSVs using specific spectral bands (Blue, Green, Red, Near-Infrared (NIR), and Short-Wave Infrared Band 2 (SWIR2)) derived from Landsat 8 OLI imagery. Canonical correlation analysis (CCA) uncovered the intricate relationships between climatic variables and OSV variations. The results reveal the following: (1) All Landsat 8 OLI spectral bands showed a negative correlation with the Pinus yunnanensis forest AGB, with OSVs ranging from 104.42 t/ha to 209.11 t/ha, peaking in the southwestern region and declining to the lowest levels in the southeastern region. (2) CCA effectively explained 93.2% of the OSV variations, identifying annual mean temperature (AMT) as the most influential climatic factor. Additionally, the mean temperature of the wettest quarter (MTQ) and annual precipitation (ANP) were significant secondary determinants, with higher OSV values observed in warmer, more humid areas. These findings offer important insights into climate-driven OSV variations, reducing uncertainty in forest AGB estimation and enhancing the precision of AGB estimations in future research.

Southeast Asia (SEA) has seen strong climatic oscillations and fluctuations in sea levels during the Quaternary. The impact of past climate changes on the evolution and distribution of local flora in SEA is still poorly understood. Here we aim to infer how the Quaternary climate change affects the evolutionary process and range shifts in two pine species. We investigated the population genetic structure and diversity using cytoplasmic DNA markers, and performed ecological niche modeling to reconstruct the species past distribution and to project range shift under future climates. We found substantial gene flow across the continuous distribution of the subtropical Pinus yunnanensis. In contrast, the tropical Pinus kesiya showed a strong population structure in accordance with its disjunct distribution across montane islands in Indochina and the Philippines. A broad hybrid zone of the two species occurs in southern Yunnan. Asymmetric introgression from the two species was detected in this zone with dominant mitochondrial gene flow from P. yunnanensis and chloroplast gene flow from P. kesiya. The observed population structure suggests a typical postglaciation expansion in P. yunnanensis, and a glacial expansion and interglacial contraction in P. kesiya. Ecological niche modeling supports the inferred demographic history and predicts a decrease in range size for P. kesiya under future climates. Our results suggest that tropical pine species in SEA have undergone evolutionary trajectories different from high latitude species related to their Quaternary climate histories. We also illustrate the need for urgent conservation actions in this fragmented landscape. [ABSTRACT FROM AUTHOR]

[Objective] This study explored the regulation mechanism of non-structural carbohydrates and endogenous hormones in Pinus yunnanensis seedling under drought stress. [Method] Two-year-old P. yunnanensis seedlings were selected for treatments with relative soil water content controlled at 75% - 85% (CK), 60%-70% (light drought), 45% - 55% (moderate drought) and 30% -40% (severe drought) of the maximum water holding capacity in field by weighing. Contents of non-structural carbohydrates of soluble sugar and starch and endogenous hormones of abscisic acid (ABA), auxin (IAA), gibberllin (GA) and zeatin nucleoside (ZR) in seedling needles under different drought treatments were investigated, and their correlations were analyzed. [Result] ➀ With increasing drought, soluble sugar content in needles of P. yunnanensis seedlings gradually increased, starch content and starch allocation ratio first increased and then decreased, while soluble sugar/starch ratio and soluble sugar allocation ratio first decreased and then increased. ➁ ABA content of needles of P. yunnanensis seedlings increased significantly in all treatments compared with CK, ZR, GA and IAA contents showed a decreasing trend with the increasing drought stress, while IAA/ABA, GA/ABA and ZR/ABA ratios decreased significantly. ➂ Soluble sugar content was positively correlated with ABA content and negatively correlated with IAA, GA and ZR contents, of which the negative correlation with IAA was significant (R²=0.423 0, P<0.05). Starch content was positively correlated with ABA, IAA, GA and ZR contents, of which the correlation with GA was significant (R²=0.392 4, P<0.05). Leaf soluble sugar and starch contents were negatively correlated with IA A/ABA, GA/ABA and ZR/ABA ratios, and the correlation of soluble sugar with IAA/ABA ratio was significant (R²=0.394 3, P<0.05). [Conclusion] P. yunnanensis seedlings adapted to drought environment by adjusting conversion and distribution of soluble sugar and starch and IA A/ABA, GA/ABA and ZR/ABA ratios by accumulating growth-inhibiting ABA and reducing growth-promoting GA, IAA and ZR. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis Franch. is an economically and ecologically important pine endemic to southwest China. A large number of low-quality and low-efficiency individuals have appeared in P. yunnanensis forests due to climate change, environmental stress, and human overexploitation. There is a lack of comprehensive information about the genetic diversity, population structure and a core germplasm collection establishment with individuals taken across its natural range. Understanding the important information will be invaluable for germplasm efficient conservation and utilization. A total of 287 individuals from 10 populations across its range were analyzed using 17 polymorphic microsatellite markers. The research revealed P. yunnanensis was a typical outcrossing plant (Fis = − 0.1), maintaining moderately high genetic diversity (He = 0.540). The continuous distribution and wind-dispersal traits of two-sacs pollen and winged seeds may have promoted gene flow (Nm = 12.71) and lessened genetic differentiation between populations (Fst = 0.023). There was a lack of significant isolation by distance (P = 0.07). Geographical and ecological isolation following the uplift of the southeastern margin of the Tibetan Plateau may have contributed to the formation of three discrete groups (K = 3). A core collection of 72 individuals (25% of the whole collection) was established, of which genetic diversity parameters showed no-significance from the whole collection. In situ conservation of the three populations (XC, CY, and XP) showing distinct genetic diversity was recommended, and ex situ conservation for individuals with private alleles. The core collection was recommended as a possible germplasm resource for tree breeding and improvement. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis Franch. (Pinaceae) is an important endemic tree species that serves as a critical constituent of the forest ecosystems and plays a significant role in forestry economic production in southwest China. P. yunnanensis comprises three varieties: var. yunnanensis, var. pygmaea and var. tenuifolia, with significant variation in traits, such as height and leaf size. This study aims to characterize the habitat conditions of the three varieties and predict their potential future distributions by employing MaxEnt model. Temperature seasonality (BIO4) emerged as the most influential factor affecting the distribution of var. yunnanensis; isothermally (BIO3) stands out as the most critical factor for the distribution of var. pygmaea; whereas mean annual fire occurrence (MAF) had the greatest impact on the distribution of var. tenuifolia. Under future climate conditions, the highly and moderately suitable habitats for all the three varieties are projected to decrease, while the lowly suitable habitats are projected to increase. The distribution centroids of all the three varieties are anticipated to shift to higher latitudes. Our study characterized the habitat conditions and predicted the potential future distribution of the three Pinus yunnanensis varieties, which could help the conservation and utilization of Pinus yunnanensis varieties.

Having a spiral grain is considered to be one of the most important wood properties influencing wood quality. Here, transcriptome profiles and metabolome data were analyzed in the straight grain and twist grain of Pinus yunnanensis. A total of 6644 differential expression genes were found between the straight type and the twist type. A total of 126 differentially accumulated metabolites were detected. There were 24 common differential pathways identified from the transcriptome and metabolome, and these pathways were mainly annotated in ABC transporters, arginine and proline metabolism, flavonoid biosynthesis, isoquinoline alkaloid biosynthesis, linoleic acid metabolism, phenylpropanoid, tryptophan metabolism, etc. A weighted gene coexpression network analysis showed that the lightblue4 module was significantly correlated with 2′-deoxyuridine and that transcription factors (basic leucine zipper (bZIP), homeodomain leucine zipper (HD-ZIP), basic helix–loop–helix (bHLH), p-coumarate 3-hydroxylase (C3H), and N-acetylcysteine (NAC)) play important roles in regulating 2′-deoxyuridine, which may be involved in the formation of spiral grains. Meanwhile, the signal transduction of hormones may be related to spiral grain, as previously reported. ARF7 and MKK4_5, as indoleacetic acid (IAA)- and ethylene (ET)-related receptors, may explain the contribution of plant hormones in spiral grain. This study provided useful information on spiral grain in P. yunnanensis by transcriptome and metabolome analyses and could lay the foundation for future molecular breeding. [ABSTRACT FROM AUTHOR]

Prescribed burning is a widely used fuel management employed technique to mitigate the risk of forest fires. The Pinus yunnanensis Franch. forest, which is frequently prone to forest fires in southwestern China, serves as a prime example for investigating the effects of prescribed burning on the flammability of surface dead fuel. This research aims to establish a scientific foundation for managing dead fuel in forests, as well as fire prevention and control strategies. Field data was collected from P. yunnanensis forests located in central Yunnan Province in 2021 and 2022. The study implemented a randomized complete block design with two blocks and three treatments: an unburned control (UB), one year after the prescribed burning (PB1a), and three years after the prescribed burning (PB3a). These treatments were evaluated based on three indices: surface dead-bed structure, physicochemical properties, and potential fire behavior parameters. To analyze the stand characteristics of the sample plots, a paired t-test was conducted. The results indicated no significant differences in the stand characteristics of P. yunnanensis following prescribed burning (p > 0.05). Prescribed burning led to a significant decrease in the average surface dead fuel load from 10.24 t/ha to 3.70 t/ha, representing a reduction of 63.87%. Additionally, the average fire−line intensity decreased from 454 kw/m to 190 kw/m, indicating a decrease of 58.15%. Despite prescribed burning, there were no significant changes observed in the physical and chemical properties of dead fuels (p > 0.05). However, the bed structure of dead fuels and fire behavior parameters exhibited a significant reduction compared with the control sample site. The findings of this study provide essential theoretical support for the scientific implementation of prescribed burning programs and the accurate evaluation of ecological and environmental effects post burning. [ABSTRACT FROM AUTHOR]

【Objective】 The nutrient allocation of plants can reflect their material and energy strategies, but it is cumbersome to determine the nutrient allocation mode of each organ of the plant. An estimation model can be constructed based on the content correlation between various organs, which can be used to estimate the nutrient content of a single plant using easily sampled organs and provide a way to quickly evaluate the nitrogen, phosphorus and potassium content of seedlings. 【Method】 Taking Pinus yunnanensis seedlings as the research object, the biomass, nitrogen content, phosphorus content, and potassium content were measured according to three organs: Root, stem, and needle. Estimation models of seedling biomass per plant (Mp), nitrogen storage per plant (NRp), phosphorus storage per plant (pRp) and potassium storage per plant (KRp) were constructed.The scaling relationships between needle leaf biomass and single plant biomass of P.yunnanensis seedlings, the biomass of a single plant and the nitrogen storage of a single plant, the phosphorus storage of a single plant, and the potassium storage of a single plant were analyzed.The correlations between the biomass of a single plant of P.yunnanensis seedlings and the storage of nitrogen, phosphorus storage of a single plant, and potassium storage of a single plant were clarified.【Result】 The needle leaf biomass (ML) of P.yunnanensis seedlings could well fit the biomass of individual plants after logarithmic transformation (R²= 0.9988, P＜0.01), and Mp=ML+10-0.235 ML0.300+10-0.334 ML0.598. Using the nitrogen content (NL), phosphorus content (PL) and potassium content (KL) of needles could also be used to fit the nitrogen storage per plant, the phosphorus storage per plant, potassium storage per plant, respectively, and the fitting models were: NRp=MLNL+10-0.235ML0.300 (-0.1942NL+4.3979) +10-0.334 ML0.598 (-0.3337NL+7.2187), pRp=MLPL+10-0.235 ML0.300 (0.0120PL+0.9744) +10-0.334 ML0.598 (0.0841PL+1.1340), and KRP=MLKL+10-0.235 ML0.300 (0.1318KL+7.4434) +10-0.334 ML0.598 (0.1051KL+6.4952). Using the measured data to further verify that model could better estimate the corresponding indicators. 【Conclusion】 The model constructed by taking the biomass and nutrient content of coniferous organs as variables can well estimate the biomass, nitrogen storage, phosphorus storage and potassium storage for P.yunnanensis plant, which is an important method for rapid estimation. [ABSTRACT FROM AUTHOR]

The seasonal variations in carbon (C), nitrogen (N), and phosphorus (P) at the organ level of Pinus yunnanenis during different season are poorly understood. In this study, the C, N, P, and their stoichiometric ratios in various organs of P. yunnanensis during the four seasons are discussed. The middle and young aged P. yunnanensis forests in central Yunnan province, China were chosen, and the contents of C, N, and P in fine roots (<2 mm), stems, needles, and branches were analyzed. The results showed that the C, N, P contents and their ratios in P. yunnanensis were significantly influenced by season and organ, less affected by age. The C content of the middle-aged and young forests decreased continuously from spring to winter, whereas N and P first decreased and then increased. No significant allometric growth relationships were observed between P-C of the branches or stems in the young and middle-aged forests, whereas a significant allometric growth relationship existed for N-P of needles in the young stands, indicating that the P-C and N-P nutrient distribution patterns shows different trends in the organ level in different age stands. The pattern of P allocation between organs shows differences in stand age, with more allocation to needles in middle-aged stands and more allocation to fine roots in young stands. The N:P ratio in needles was less than 14, indicating that P. yunnanensis was mainly limited by N and increasing the application of N fertilizer would be beneficial for the productivity of this stand. The results will be helpful to nutrient management in P. yunnanensis plantation. [ABSTRACT FROM AUTHOR]

Pinus densata Mast. is considered a homoploid hybrid species that originated from the putative parent species Pinus tabuliformis Carr. and Pinus yunnanensis Franch., but the mechanism of the adaptive differentiation of P. densata and its parents in native habitats has not been reported. Therefore, the overlapping distribution areas between P. densata and P. yunnanensis in the heart of the Hengduan Mountains were chosen. The adaptive differentiation mechanism of the homoploid hybrids and their parents with respect to the elevational gradient was studied based on the morphological features and the different strategies of recruiting endophytic microbial communities from the rhizosphere soil. The results showed that (1) the height and diameter at breast height were the greatest at 2600 m and 2900 m, and from 2700 m to 2900 m, three-needle pines (P. yunnanensis-like type) transitioned into two-needle pines (P. densata-like type). (2) The recruitment of rhizosphere microbial communities was driven by the C, N, P and pH values which showed significant elevation features. (3) There was a significant difference in the recruitment strategies of endophytes between the P. yunnanensis-like type and P. densata-like type. Pinus densata mainly reduced the recruitment of Mucoromycota (fungi) and increased the recruitment of Proteobacteria (bacteria), which may be related to environmental adaptability, quorum sensing and the metabolism of auxiliary factors and vitamins at high elevations. (4) The root endophytic microbiome was enriched in the rare groups from the rhizosphere soil microbial pool. The results of this study provide new insights and new ideas for environmental adaptability and differentiation in homoploid hybrid speciation. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of Botanical Research is the property of Bulletin of Botanical Research Editorial Department 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.)

Background: Pinus yunnanensis is a major silvicultural species in Southwest China. Currently, large areas of twisted-trunk Pinus yunnanensis stands severely restrict its productivity. Different categories of rhizosphere microbes evolve alongside plants and environments and play an important role in the growth and ecological fitness of their host plant. However, the diversity and structure of the rhizosphere microbial communities between P. yunnanensis with two different trunk types—straight and twisted—remain unclear. Methods: We collected the rhizosphere soil of 5 trees with the straight and 5 trees with the twisted trunk type in each of three sites in Yunnan province. We assessed and compared the diversity and structure of the rhizosphere microbial communities between P. yunnanensis with two different trunk types by Illumina sequencing of 16S rRNA genes and internal transcribed spacer (ITS) regions. Results: The available phosphorus in soil differed significantly between P. yunnanensis with straight and twisted trunks. Available potassium had a significant effect on fungi. Chloroflexi dominated the rhizosphere soils of the straight trunk type, while Proteobacteria was predominant in the rhizosphere soils of the twisted trunk type. Trunk types significantly explained 6.79% of the variance in bacterial communities. Conclusion: This study revealed the composition and diversity of bacterial and fungal groups in the rhizosphere soil of P. yunnanensis with straight and twisted trunk types, providing proper microbial information for different plant phenotypes. [ABSTRACT FROM AUTHOR]

Accurate information concerning crown profile is critical in analyzing biological processes and providing a more accurate estimate of carbon balance, which is conducive to sustainable forest management and planning. The similarities between the types of data addressed with LSTM algorithms and crown profile data make a compelling argument for the integration of deep learning into the crown profile modeling. Thus, the aim was to study the application of deep learning method LSTM and its variant algorithms in the crown profile modeling, using the crown profile database from Pinus yunnanensis secondary forests in Yunnan province, in southwest China. Furthermore, the SHAP (SHapley Additive exPlanations) was used to interpret the predictions of ensemble or deep learning models. The results showed that LSTM's variant algorithms was competitive with traditional Vanila LSTM, but substantially outperformed ensemble learning model LightGBM. Specifically, the proposed Hybrid LSTM-LightGBM and Integrated LSTM-LightGBM have achieved a best forecasting performance on training set and testing set respectively. Furthermore, the feature importance analysis of LightGBM and Vanila LSTM presented that there were more factors that contribute significantly to Vanila LSTM model compared to LightGBM model. This phenomenon can explain why deep learning outperforms ensemble learning when there are more interrelated features. [ABSTRACT FROM AUTHOR]

Fire frequently causes strong disturbance in forests. Belowground fungi are sensitive to forest fire disturbance and can affect vegetation restoration. Our objective was to investigate the responses of belowground fungi under two tree species to forest fire in a mixed forest in Yunnan Plateau. Samples from three 'sample sites' (roots, rhizosphere soil and bulk soil) were collected from two plant species, Pinus yunnanensis and Eucalyptus citriodora , and were analyzed for fungal diversity and community composition. Fungi were identified using high-throughput sequencing. Shannon index and principal coordinate analysis were used for diversity and network analysis. LEfSe and FUNGuild were used to analyze the community composition, trophic mode and guild. Alpha diversity in bulk soil was higher than that in rhizosphere soil and roots, while the community composition was significantly different among the three sample sites. Fungal network complexity of E. citriodora was higher than that of P. yunnanensis. The relative abundance of Mucoromycota in the three sample sites was higher for P. yunnanensis than E. citriodora. Most of the top 10 dominant genera of the two plant species were saprotrophic fungi. In the comparison of biomarker, ectomycorrhizal fungi dominated in the roots and rhizosphere soil of P. yunnanensis , while both saprotrophic fungi and symbiotic fungi were in the roots and rhizosphere soil of E. citriodora. Our findings suggest that, following a forest fire, responses of fungal community are species-specific in Yunnan Plateau. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) 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.)

【Objective】The purpose of this study was to reveal the effects of flat stubble in different seasons on biomass allocation and allometric growth of Pinus yunnanensis Franch. 【Method】The biomass accumulation and biomass allocation patterns of P. yunnanensis in spring, summer and autumn were studied by digging method and weighing method, and the allometric growth relationships between organs and total biomass, organs and organs biomass were analyzed by allometric growth analysis method. 【Result】Except lateral roots, the biomass accumulation of other components in spring was significantly higher than that in summer and autumn; In spring and autumn, the biomass distribution of needles and stems was significantly greater than that of other components, while in summer, the biomass distribution of stems was significantly greater than that of other components; In spring and summer, the biomass distribution of lateral roots was significantly lower than that of other components, while in autumn, the sprouting was significantly lower than that of other components. The trade-off law of underground and aboveground biomass was as follows: the underground and aboveground biomass grew at the same speed in spring and summer, and tend to grow above the ground in autumn. In different seasons of flat stubble, the growth rate of needles in seedling components maintained the maximum, followed by lateral roots; However, there were significant differences in the growth rate between taproot and stem, taproot and needle, sprout and needle, sprout and taproot component biomass, indicating that the allometric growth relationship was significantly affected by the flat stubble season. The effects of flat stubble on the growth rate of seedling components in different seasons were discrepant, the highest growth rate was needle leaf, followed by lateral root; From the growth rate between sprouts and biomass of each component, the growth rate of sprouts with flat stubble was the fastest in autumn, the second in spring and the slowest in summer. 【Conclusion】The flat stubble season changed the biomass accumulation and biomass distribution mode of P. yunnanensis. The flat stubble season had different effects on the allometric growth of each component, but the needle and lateral roots in the seedling component always maintained a large growth rate, which was not affected by the flat stubble season. Considering comprehensively that P. yunnanensis seedlings with flat stubble should be stubble in spring or autumn, the biomass of flat stubble initiation zone in spring was large, and the growth rate of flat stubble initiation zone in autumn was fast. [ABSTRACT FROM AUTHOR]

Tomicus yunnanensis Kirkendall (Coleoptera: Scolytinae) is a stem-boring pest that endangers Pinus yunnanensis Franch (Pinales:Pinoideae), which seriously affects the ecological environment safety in southwest China. In order to understand the potential distribution pattern and change in the potential distribution of P. yunnanensis and T. yunnanensis, this study used the maximum entropy model to predict the distribution of potentially suitable areas for P. yunnanensis and T. yunnanensis and explored the relationships between their different spatiotemporal distributions based on change analysis. The experimental results show that altitude is the main factor restricting the current distribution of P. yunnanensis. The current suitable areas of P. yunnanensis are mainly distributed in Yunnan, Sichuan and Guizhou. The minimum temperature of the coldest month is the main factor affecting the current distribution of T. yunnanensis. The current suitable areas of T. yunnanensis are mainly distributed in Yunnan, Sichuan and Tibet. Under future climate scenarios, the total suitable areas of P. yunnanensis and T. yunnanensis are expected to increase. The suitable areas tend to move to higher altitudes in the west and higher latitudes in the north. At the same time, this study finds that there is an obvious bottleneck of expansion to northeastern Sichuan near the Daba Mountains. The results of intersection analysis showed that, with future climate change, P. yunnanensis and T. yunnanensis mainly showed lowly suitable (or unsuitable)—lowly suitable (or unsuitable) to moderately (or highly) suitable—and moderate (or high) variation patterns of suitable areas under the SSP1-2.6 climate scenario. These results will provide an important basis for the breeding of P. yunnanensis and controlling T. yunnanensis. [ABSTRACT FROM AUTHOR]

Due to climate change, it is significant to explore the impact of rising temperatures on the distribution of Dendrolimus houi Lajonquiere (Lepidoptera) and its host plants, Pinus yunnanensis and Cryptomeria fortunei, and to simulate their suitable future distribution areas in order to provide a theoretical basis for the monitoring of, and early warning about, D. houi and the formulation of effective prevention and control policies. Based on the known distribution areas of, and relevant climate data for, D. houi, P. yunnanensis, and C. fortunei, their suitable habitat in China was predicted using the ENMeval data package in order to adjust the maximum entropy (MaxEnt) model parameters. The results showed that the regularization multiplier was 0.5 when the feature combination was LQHPT, with a MaxEnt model of lowest complexity and excellent prediction accuracy. The main climate variable affecting the geographical distribution of D. houi, P. yunnanensis, and C. fortunei is temperature, specifically including isothermality, temperature seasonality, maximum temperature of warmest month, minimum temperature of warmest month, average temperature of coldest quarter. The potential suitable distribution areas for P. yunnanensis and D. houi were similar under climate change, mainly distributed in southwest China, while C. fortunei was mainly distributed in southeast China. Under different future-climate scenarios, the areas suitable for the three species will increase, except for P. yunnanensis in the 2070s under Shared Socioeconomic Pathway 5–8.5. With climate change, all three species were found to have a tendency to migrate to higher latitudes and higher altitudes. The centroids of the areas suitable for P. yunnanensis and D. houi will migrate to the northwest and the centroids of the areas suitable for C. fortunei will migrate to the northeast.

It has been widely reported that biodiversity, ecosystems, and functional traits are positively interrelated in natural forest ecosystems. However, it remains unclear whether these relationships should be expected in secondary forests. In this study, we hypothesized that the multifunctionality (EMF) is affected by the climate dependency of tree-species diversity and stand attribute diversity in a secondary forest dominated by Pinus yunnanensis. By using forest inventory data from a wide range of areas, we quantified the aboveground biomass, soil organic carbon, ratio of soil carbon and nitrogen, total soil nitrogen, total soil phosphorus, total soil potassium, tree-species diversity, and stand attribute diversity (i.e., individual tree-size variations). We also quantified the climate data, including the mean annual temperature (MAT), and mean annual precipitation (MAP). We found that a higher MAT directly constrains all the ecosystem multifunctionalities (EMFs) and three of the five single functions. A higher MAP was negatively correlated with all the EMFs and four of the five single functions, but indirectly through diversity indices. Stand attribute diversity better explained the EMFs rather than tree species diversity. Meanwhile, most of the single functions were highly correlated with stand attribute diversity rather than tree species diversity. These results highlight the importance of diversity in promoting forest multifunctionality and underscore the importance of the climate context in defining EMF and shaping the relationship between diversity and ecosystem functions. We argue that the climate context should be taken into account when maximizing forest complexity, so as to enhance the multifunctionality of Pinus yunnanensis secondary forests. [ABSTRACT FROM AUTHOR]

Outbreaks of pine shoot beetles (Tomicus spp.) have caused widespread tree mortality in Southwest China. However, the understanding of the role of climatic drivers in pine shoot beetle outbreaks is limited. This study aimed to characterize the relationships between climate variables and pine shoot beetle outbreaks in the forests of Yunnan pine (Pinus yunnanensis Franch) in Southwest China. The pine shoot beetle-infested total area from 2000 to 2017 was extracted from multi-data Landsat images and obtained from field survey plots. A temporal prediction model was developed by partial least squares regression. The results indicated that multi consecutive year droughts was the strongest predictor, as such a condition greatly reduced the tree resistance to the beetles. The beetle-infested total area increased with spring temperature, associated with a higher success rate of trunk colonization and accelerated larval development. Warmer temperatures and longer solar radiation duration promoted flight activity during the trunk transfer to the shoot period and allowed the completion of sister broods. Multi consecutive year droughts combined with the warmer temperatures and higher solar radiation duration could provide favorable conditions for shoot beetle outbreaks. Generally, identifying the climate variables that drive pine shoot beetle outbreaks could help improve current strategies for outbreak control. [ABSTRACT FROM AUTHOR]

Pinus yunnanensis forest is a unique forest type in southwest China and one of the main forest types in Yunnan Province, which also has great ecological, economic and social significance. Understanding the changes in the stoichiometric characteristics is a key to study the nutrient cycling, limiting factors and stability mechanisms of the forest ecosystem. However, the stoichiometric characteristics, stability of the ecosystem of P. yunnanensis natural forests and whether they are limited by nutrients are still poorly understood. Based on a K-S test, ANOVA analysis and OLS regression analysis, we analyzed the concentrations of leaf C, N and P in 48 woody species of natural P. yunnanensis forests from 122 plots to explore the pattern of leaf C:N:P stoichiometry. Our results showed that the mean values of leaf C, N and P plus C:N, C:P and N:P for the 48 woody species were 451.12, 11.05 and 1.11 mg/g and 45.03, 496.98 and 11.27, respectively. The coefficients of variation of leaf C, N and P plus C:N, C:P and N:P were 5.29%, 36.75%, 51.53%, 29.63%, 43.46% and 41.68%, respectively. The geometric mean values of leaf N, P and N:P were 10.49 and 1.00 mg/g and 10.51, respectively. Leaf C and N, and C and P relationships showed significant negative correlations, but a significant positive correlation was observed between leaf N and P. There were significant differences in leaf N and C:N across functional groups. There were significant differences in leaf C and P between evergreen and deciduous, conifer and broadleaf trees. Significant differences in leaf C:P were only observed between evergreen and deciduous trees, and significant differences in leaf N:P were observed between conifer and broadleaf trees. The relatively low N:P in all sampled trees indicated that N was a limiting factor in the distribution of natural P. yunnanensis forests. However, the higher leaf C:N and C:P ratios indicated that the P. yunnanensis natural forest ecosystem was in a relatively stable state. [ABSTRACT FROM AUTHOR]

The effects of low-intensity and high-frequency prescribed burning on the soil CO2 emissions from Pinus yunnanensis forestland should be explored to achieve sustainable operation and management under fire disturbance. A Li-6400XT portable photosynthesis meter (equipped with a Li-6400-09 soil respiration chamber) and a TRIME®-PICO 64/32 soil temperature and moisture meter were used to measure the soil CO2 flux, soil temperature, and soil moisture at fixed observation sites in two treatments (i.e., unburned (UB) and after prescribed burning (AB)) in a Pinus yunnanensis forest of Zhaobi Mountain, Xinping County, Yunnan, China from March 2019 to February 2021. We also determined the relationships between the soil CO2 flux and soil hydrothermal factors. The results showed that (1) the soil CO2 flux in both UB and AB plots exhibited a significant unimodal trend of seasonal variations. In 2020, the highest soil CO2 fluxes occurred in September; they were 7.08 μmol CO2·m−2·s−1 in the morning and 7.63 μmol CO2·m−2·s−1 in the afternoon in the AB treatment, which was significantly lower than those in the UB treatment (p < 0.05). The AB and the UB treatment showed no significant differences in annual soil carbon flux (p > 0.05). (2) The relationship between the soil CO2 flux and moisture in the AB and UB plots was best fitted by a quadratic function, with a degree of fitting between 0.435 and 0.753. The soil CO2 flux and soil moisture showed an inverted U-shaped correlation in the UB plot (p < 0.05) but a positive correlation in the AB plot (p < 0.05). Soil moisture was the key factor affecting the soil CO2 flux (p < 0.05), while soil temperature showed no significant effect on soil CO2 flux in this area (p > 0.05). Therefore, the application of low-intensity prescribed burning for fire hazard reduction in this region achieved the objective without causing a persistent and drastic increase in the soil CO2 emissions. The results could provide important theoretical support for scientific implementation of prescribed burning, as well as scientific evaluation of ecological and environmental effects after prescribed burning. [ABSTRACT FROM AUTHOR]

The Yunnan pine (Pinus yunnanensis Franch.) is one of the primary forest vegetation types in Yunnan Province and has prominent economic value and ecological significance. Monitoring changes in Yunnan pine forests contributes to their health management. The normalized differential vegetation index (NDVI) is an essential indicator for studying regional vegetation change. Landsat images were used to analyze the NDVI changes of Yunnan pine forests in rainy and dry seasons as well as the NDVI changes of Yunnan pine forests from 2009 to 2020. The results showed that the NDVI in Yunnan pine forests showed opposite trends in the rainy and dry seasons, with an increase in the rainy season and a decrease in the dry season. The areas of NDVI decline during the rainy season are mainly located at the edges of the forest area, with very few within the forest area. The main reason for the decline in NDVI within the forest area was pests. From 2009 to 2020, the areas where NDVI increased and decreased were 92.23% and 7.77% of the pine forests, respectively. The decreasing areas were mainly located at the edges of the pine forests, with sporadic distribution within the forest areas. The drought led to a significant decline in NDVI in the forest area in 2010 and 2013. Due to the lack of protective measures, the forest area in Xijiekou Town was severely infested with pests, with complex NDVI changes and strong fluctuations, and areas of severe pest infestation could be detected by NDVI imagery. This study is meaningful for forest protection and explores the potential capability of Landsat imagery for pest detection. [ABSTRACT FROM AUTHOR]

There is still limited information on how genetic introgression impacts morphological variation and population fitness in long-lived conifer species. Two closely related pine species, Pinus kesiya Royle ex Gordon and Pinus yunnanensis Franch. are widely distributed over Southeast Asia and Yunnan province of China, with a large spatial scale of asymmetric genetic introgression and hybridization, and form a hybrid lineage, P. kesiya var. langbianensis, where their ranges overlap in southeast Yunnan. We compared seed trait variation and germination performance between hybrids and parental species and characterized environmental gradients to investigate the genetic and ecological evolutionary consequences of genetic introgression. We found that seed width (SW) differed significantly among the three pines, and all the seed traits were significantly negatively correlated with latitude and associated with the mean temperatures of the driest and wettest quarters. A higher germination fitness of hybrids was detected at a low temperature, indicating that they had better adaptability to temperature stress than their parental species during the germination process. Our results suggest that environmental factors shape seed phenotypic variation in the pine species and that genetic introgression significantly affects seed germination fitness. Therefore, assisting gene flow in natural forest populations might facilitate their adaptation to climate change. [ABSTRACT FROM AUTHOR]

Abstract Background The impacts of selective logging on ecosystem multifunctionality (EMF) remain largely unexplored. In this study, we analyzed the response of nine variables related to four ecosystem functions (i.e. nutrient cycling, soil carbon stocks, decomposition, and wood production) to five selective logging intensities in a Pinus yunnanensis-dominated forest. We included a control group with no harvest to evaluate the potential shifts in EMF of the P. yunnanensis forests. We also assessed the relationship between above- and belowground biodiversity and EMF under these different selective logging intensities. Additionally, we evaluated the effects of biotic and abiotic factors on EMF using a structural equation modeling (SEM) approach. Results Individual ecosystem functions (EFs) all had a significant positive correlation with selective logging intensity. Different EFs showed different patterns with the increase of selective logging intensity. We found that EMF tended to increase with logging intensity, and that EMF significantly improved when the stand was harvested at least twice. Both functional diversity and soil moisture had a significant positive correlation with EMF, but soil fungal operational taxonomic units (OTUs) had a significant negative correlation with EMF. Based on SEM, we found that selective logging improved EMF mainly by increasing functional diversity. Conclusion Our study demonstrates that selective logging is a good management technique from an EMF perspective, and thus provide us with potential guidelines to improve forest management in P. yunnanensis forests in this region. The functional diversity is maximized through reasonable selective logging measures, so as to enhance EMF.

Analysis of height growth of dominant trees is crucial for accurate evaluation of site quality and how this influences stand characteristics. This study explores, whether stand origin, tree species composition and stand density influence the growth process of stand dominant height. We used forest resource inventory data from 1283 permanent plots in Sichuan Province, China. Three dominant trees were selected from each permanent plot to calculate the average dominant height and diameter at breast height (DBH). The Chapman-Richards equation was used to construct a dominant height prediction model of each tree species based on DBH. The effects of the stand origin, species composition, and stand density on the upper asymptote parameter a, shape parameter b, and growth rate parameter c were analyzed using a dummy variable method. The results show that there was no statistically significant difference in parameters a, b, and c among different stand origins, species composition, and stand density. The upper asymptote parameters of the stand with a natural origin were greater than stands with an artificial origin. Species composition influenced the parameters among different coniferous species but was associated with large coefficients of variation, especially for broadleaf species. Stand density moderatly influenced the model parameters for all species. With an increase in stand density, the influence of stand density on the model parameters decreased gradually. Our results confirm that the relationship between DBH and height of dominant trees is useful to evaluate site productivity. However, this method has to consider stand origin and differences in stand density and species composition, especially for species with DBHheight relations sensitive to stand conditions. [ABSTRACT FROM AUTHOR]

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