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Abstract:
Objective  The population of Populus euphratica recovered to a certain extent following the ecological water conveyance project, but its restoration result was far less significant than for Tamarix ramosissima, which overlaps its ecological niche. To provide scientific reference for protecting and managing P. euphratica forests and developing ecological water conveyance projects in oases, this study explores whether the adaptability advantages of P. euphratica population are affected by symbiosis with T. ramosissima in different soil water and salinity environments.   Method  P. euphratica and T. ramosissima forests in the arid area in north-western China were selected as the key constructive species of riparian forest communities, and two common soil water and salinity habitats with high and moderate soil moisture and salinity were established as a means of analysing the spatial distribution of both species and their relationships with saline water.   Result  (1) In an environment with relatively high water and salt content, the P. euphratica population demonstrated a declining trend, with relatively few young woods and a limited amount of regeneration, whereas the T. ramosissima population was stable. The population structure of P. euphratica was found to be stable with little difference between each age class, whereas T. ramosissima was found to have a growing population. (2) Ins different salt and water environment, both species were mainly distributed in aggregation as a means of resisting the stress of an adverse environment, and P. euphratica seedling growth was inhibited by T. ramosissima. (3) Different soil water and salinity environments resulted in differences in the abundance of both species. The ratio of T. ramosissima to P. euphratica was found to have a positive correlation with salinity, but as the water content increased, the number of T. ramosissima decreased and P. euphratica increased with lower salt content.   Conclusion  The results further verify that competition is an important factor for the decline of P. euphratica during the succession process, with the exception of environmental filtering. T. ramosissima will gradually replace P. euphratica in high-salt habitats, but improved water conditions could arrest this trend.
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Objective  This paper aims to explore the relationship between DBH and the area and volume of mound-pit complexes formed by uprooted trees in the natural forest in south of the Xiaoxing’an Mountains of northeastern China. The DBH of uprooted trees was used to predict the morphological characteristics of the mound and pit complex, which could provide reference for the future prediction of morphological characteristics of the mound and pit complex.  Method  In this paper, the natural forest in south of the Xiaoxing’an Mountains area was taken as the object, and the combined methods of field investigation and statistical analysis were adopted. By investigating 320 mound-pit complexes formed by uprooted trees with different decay levels at the similar altitude, the characteristics of uprooted trees, mound-pit complexes and topographic features were recorded. The formation time of uprooted trees and its mound-pit complex was deduced according to different decay levels of uprooted trees, and the influence of DBH and decay level of uprooted trees on the morphological characteristics of mound-pit complex was analyzed, and the relationship between the morphological characteristics and DBH of uprooted trees was fitted.  Result  (1) Three tree species with the highest frequency of uprooted trees were Abies nephrolepis, Picea Koraiensis and Pinus koraiensis, which were mainly coniferous trees. (2) The quantities of uprooted trees of decay level Ⅰ with the lightest level> those of level Ⅱ with the medium level > those of Ⅲ level with the highest level, and the quantities of dominant decay level Ⅰ accounted for 58% of the total quantities of uprooted trees in the study area.(3) With the increase of uprooted trees’ decay level, their area and volume of pits decreased, but the area and volume of mounds increased. (4) DBH of uprooted trees was positively correlated with the area and volume of mound-pit complexes (P < 0.01).  Conclusion  The decay level of uprooted trees is significantly negative correlated with the area and volume of pit, significantly positive correlated with the area and volume of mound. The area and volume of mound-pit complexes increase with the increase of uprooted trees’ DBH. The area and volume of pits formed by uprooted trees change exponentially with the variation in their DBH.
Abstract:
Objective  Bayesian statistics can use prior information and sample information to make statistical inference, which can effectively improve the reliability and stability of model parameters.   Method  The data were obtained from three 100 m × 100 m sample plots of Picea schrenkiana, and the classical statistical method (maximum likelihood method) and Bayesian method were used to construct the tree diameter-height model of Picea schrenkiana. 80% of the sample plots data were randomly selected for modelling, and 20% of the sample plots data were validated to compare and analyse the performance and parameters distribution of the non-linear model and non-linear mixed effects model based on the classical method and the Bayesian model and Hierarchical Bayesian model based on the Bayesian method.   Result  By comparing the non-linear model and Bayesian model, the confidence intervals for the three parameters a, b and c of the Bayesian model were 53.86%, 46.87% and 65.17% narrower than those of the non-linear model, respectively. In contrast, the confidence intervals for the fixed effect parameters of the Hierarchical Bayesian model were 37.21%, 62.62% and 49.31% narrower than those of the non-linear mixed effects model, but the confidence intervals for the standard deviation of the random effect parameters were more spread out compared to those of the Hierarchical Bayesian model and the non-linear mixed effects model. The models based on the Bayesian approach all had lower parameters standard deviations than those based on the classical approach. The fitting results of the four diameter-height models showed that the Hierarchical Bayesian model fitted better than the other three models, with a coefficient of determination (R2) of 0.961. The fitting accuracy showed that the prediction accuracy of the Hierarchical Bayesian model was slightly higher than that of the non-linear mixed effects model.   Conclusion  Although there is no significant difference between the two mixed models in terms of fitting results, the Hierarchical Bayesian model is better in terms of stability of parameters estimation and its prediction is more reliable compared with the non-linear mixed effects model.
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Objective  This study aimed to analyze the aboveground biomass allocation patterns varying with tree size, and to establish additive allometric biomass equations for accurate estimation of biomass and carbon sequestration of loblolly pine plantations in Ji’an Region, Jiangxi Province of eastern China.  Method  A total of 35 trees covering different diameter classes were harvested and measured for wood (inside bark), bark, branch, and foliage biomass in the Wugongshan Forest Farm of Anfu County of Jiangxi Province. The share of biomass allocated to different components and its variation trend with tree size were assessed by calculating the biomass fractions. The best biomass model for each component was determined by testing the diameter (D) and height (H) as predictors. A seemingly unrelated regression method with a unique weighting function for each equation was applied to establish additive systems of biomass models and to overcome the model heteroscedasticity. The predictive ability was validated by the leave-one-out cross-validation method.   Result  With the increase of tree size, stem and branch biomass ratios increased and the ratios for bark and foliage decreased. Diameter proved to be the most important predictor for each biomass component, the model coefficients were extremely significant with good fitting results (\begin{document}$R_{{\text{adj}}}^2$\end{document} ranged from 0.91 to 0.97). Adding tree height can help to improve the model fit and performance for wood and bark, but it is not conducive to the improvement of branch and leaf models, and the coefficient for tree height is non-significant. Compared with the previously published biomass models of loblolly pine, the models developed in this study performed well and had a small bias with total relative error (TRE) basically within ±1%.   Conclusion  Tree size is the main factor affecting biomass allocation, and trunk accounted for most of the aboveground biomass, followed by branch and foliage. Wood and bark biomass models are best fitted with D2H, while models with D alone perform best for branch and foliage biomass. The developed additive biomass models based on the most suitable predictors show high prediction accuracy, indicating that the models can be applied in biomass estimation of loblolly pine plantations in Ji’an Region, Jiangxi Province of eastern China.
Abstract:
Objective  Telomere genes play an important role in the process of plant tissue senescence and differentiation. In this study, the telomere genes CcTBP1 and CcPOT1 of ancient Cinnamomum camphora were cloned and analyzed by bioinformatics, subcellular localization and detection of their expression level in ancient C. camphora and its rejuvenating cuttings, to preliminarily reveal the function of telomere genes in the process of adventitious root formation of ancient C. camphora rejuvenating cuttings, and lay a foundation for exploring the telomere regulation mechanism of ancient C. camphora rejuvenating cuttings.  Method  In this study, leaf RNA was extracted from 1200 years old ancient C. camphora. The telomere genes CcTBP1 and CcPOT1 were cloned by PCR and homologous cloning, as well the bioinformatics analysis was conducted to their sequences. The over-expression vector was constructed for subcellular localization analysis. The CcTBP1 and CcPOT1 expression level of different tissues and adventitious root formation process was analyzed by qRT-PCR in ancient C. camphora and its rejuvenation cutting seedlings.  Result  (1) Two telomere genes were cloned, named CcTBP1 and CcPOT1, respectively. The CDS sequence of CcTBP1 gene was 2 163 bp and encoded 720 amino acids. The CDS sequence of CcPOT1 gene was 1 407 bp and encoded 468 amino acids. (2) The results of sequence similarity and phylogenetic tree analysis showed that the sequence similarity of CcTBP1 protein and Camphor tree RWR76720.1 was 98%, and their genetic relationship was the closest; the sequence similarity of CcPOT1 protein and camphor tree RWR96964.1 was as high as 99%, and their genetic relationship was the closest. (3) The results of subcellular localization analysis showed that CcTBP1 gene was located in the nucleus, and CcPOT1 gene was located in the cytoplasm and nucleus. (4)   Conclusion  The telomere genes CcTBP1 and CcPOT1 played an important regulation function in the adventitous root formation process of ancient C. camphora rejuvenation.
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Objective  The analysis of stand spatial structure at different growth stages is conductive to understanding stand regeneration and stability, which can provide reference for optimizing stand spatial structure and natural vegetation restoration.  Method  In the study, the evergreen broadleaved forest in Lushan Mountain, Jiangxi Province of eastern China was taken as the research object. The tree growth was divided into four stages: sapling (1 cm ≤ DBH < 5 cm), small tree (5 cm ≤ DBH < 10 cm), middle tree (10 cm ≤ DBH < 20 cm) and large tree (DBH ≥ 20 cm). The comprehensive index of spatial structure was constructed by four kinds of spatial structure parameters: mingling, neighborhood comparison, crowding degree and uniform angle index. The weight was assigned by entropy weight method.   Result  (1) The proportions of sapling, small tree, medium tree and large tree were 72.7%, 16.8%, 6.5% and 4.0%, respectively. The diameter class structure of the stand was generally inverse ‘J’ type. (2) The average mingling of sapling, small tree, middle tree and large tree were 0.609, 0.746, 0.815 and 0.822, respectively. The average neighborhood comparison of them was 0.545, 0.268, 0.132 and 0.089, respectively. The average crowding degree of them was 0.852, 0.895, 0.871 and 0.842, respectively. The average uniform angle index of them was 0.576, 0.563, 0.553 and 0.507, respectively. With the increase of diameter class, the degree of mingling and growth dominance of trees increased, and the density of trees first increased and then decreased. The distribution pattern gradually changed from aggregation distribution to random distribution. (3) The weight of neighborhood comparison of small tree, medium tree and large tree was more than 75.0%. The way of optimizing spatial structure should mainly regulate the degree of forest differentiation. The weight of mingling and neighborhood comparison of sapling were 0.364 and 0.388, respectively. To optimize its spatial structure, the degree of forest mingling and differentiation should be mainly controlled simultaneously. The comprehensive index of spatial structure was large tree (0.054) < middle tree (0.082) < small tree (0.117) < sapling (0.265).   Conclusion  The spatial structure of evergreen broadleaved forest in Lushan Mountain was gradually improved with the increase of diameter class. The best spatial structure was the large tree and the worst was the sapling. According to the spatial structure characteristics of trees at different growth stages, different forest management measures can be taken to optimize the spatial structure.
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Objective  As there is a gap on the methods of refined small-scale research on the carbon stock of urban trees, this paper proposes a technological method based on Landscape Information Modeling (LIM). It reconstructs the urban trees at a given time into 3D models and simulates the growth of the trees in a certain period of time to calculate the biomass and carbon stock. With this method, the baseline scenario of carbon stock is described.   Method  The steps of the experiment to verify this method include: the harvesting and proceeding of the point clouds; the construction of the LIM model; and the calculation and evaluation of the carbon stock of the trees. The objects of the experiment are the 19 selected Chinese scholar trees (Sophora japonica) standing in rows on both sides of the lawn on the university campus in Beijing. The point clouds harvesting is achieved by terrestrial laser scanning (TLS). The proceeding aims to segment the individual tree and reduce the density of the points. LIM model construction includes 3D digital model construction and growth simulation of individual scholar tree and a group of 19 scholar trees with GIS location. The growth simulation under baseline scenario is also included. The calculation and evaluation of the carbon stock of the trees are realized by applying an allometric growth equation under baseline scenario.   Results  The LIM model of individual scholar tree is constructed. It is with a 3D digital model that integrates the crown and roots and the optimal growth curve, that is from the reconstruction of point clouds. The LIM model is applied to simulate the dynamic growth of the individual scholar tree at the age of 8, 10, 20, 30, 40, 50 years old. The results state that under the baseline scenario, from seedling emergence to the 50th year of growth there is a net increase of 1396.87 kg and an annual increase of 33.261kg of carbon stock. Such method of LIM model construction is applied to the 19 scholar trees with different ages on campus. It is realized to simulate their individual and colonial biomass and carbon stock in 10, 20, 30, 40, 50 years. The baseline scenario of their carbon stock is described. The current average carbon stock of the 19 scholar trees is 115.33 kg. The current total carbon stock is 2191.27 kg.   Conclusion  The results state that it is feasible to apply LIM-based methods to research on the refined small-scale carbon stock of the existing urban trees. The numerical simulation of carbon stock in the LIM model is coupled with the spatial geometry model of plant growth. It is promising to have such a model coupling the carbon calculation and evaluation to much richer application scenarios, such as urban habitat protection, planning and design, project construction, operation and maintenance, asset management, and spatial governance.
Abstract:
Objective  With the acceleration of industrialization, many natural forests have been destroyed, leading to a significant decline in the quantity and quality of forests. Therefore, many measures have been taken to restore vegetation, mainly including artificial and natural restoration models. Studying the difference of soil water storage and nutrient storage of the forest under the two different restoration models will help to compare the advantages and disadvantages of these restoration models, and provide a theoretical basis for the subtropical vegetation restoration and reconstruction.  Method  In this study, three typical forests were selected, namely, the secondary forest that had been naturally restored 35 years after precise cutting, the Chinese fir forest that had been naturally restored 39 years after artificial planting of Chinese fir, and the well preserved original forest, Compare the differences of water conservation and nutrient storage capacity of different restoration models.  Result  The results showed that in terms of water storage capacity, the water holding capacity and saturated water storage capacity of Chinese fir forest and secondary forest were significantly lower than those of old-growth forest, but in terms of retained water storage capacity, Chinese fir forest and secondary forest were considerably higher than the old-growth forest, while there was a similar water storage capacity between Chinese fir forest and secondary forest; In terms of soil nutrient storage, the available nitrogen storage of old-growth forest and secondary forests were significantly higher than those of Chinese fir forests, but the available phosphorus storage of Chinese fir forests were considerably higher than those of secondary and old-growth forests; The carbon, total nitrogen and total phosphorus storages of the old-growth forest are significantly higher than those of Chinese fir forest and secondary forest, and the carbon storages and total nitrogen storages of Chinese fir forest are substantially higher than those of secondary forest, but the total phosphorus storages of Chinese fir forest are significantly lower than those of secondary forest.   Conclusion  The two restoration models are similar in soil water conservation but differ considerably in nutrient storage capacity. Different restoration models should be adopted according to the ecological restoration objectives. The natural restoration model should be used to improve available soil nitrogen and total phosphorus storages. The artificial restoration model can be applied to improve nutrient storages of available soil phosphorus, carbon, and total nitrogen.
Abstract:
Objective  The ecological significance of 4-variate distribution of stand spatial structure parameters was deeply analyzed and a comprehensive evaluation index of stand spatial structure diversity based on the relationship between adjacent trees was constructed to provide a theoretical basis for formulating targeted forest structure adjustment strategies.   Method  Based on the concept of biodiversity, taking the structural unit which composed by reference tree and its nearest four adjacent trees as the object, organically integrate the 4-variate distribution of structural parameters of uniform angle index, mingling, neighborhood comparison and crowding, as well as the number of structural unit trees and forest layers, the genetic absolute distance formula and natural logarithm are used to express the evenness and richness of structural unit types, respectively, and the stand spatial structure diversity index was constructed. The validity of the index was verified by using the long-term positioning monitoring sample plot data  Result  Used the stand spatial structure diversity index (FSD) proposed in this study to measure the spatial structure diversity of forest types in different climatic zones or different origins show that the FSD values of Quercus aliena var. acutiserrata natural forest (0.854) and broad-leaved Pinus koraiensis forest (0.852) were almost the same, indicating that the two forest stands have similar spatial structural diversity. The 4-variate distribution types of Platycladus orientalis plantation was higher than other natural forest, however, its spatial structural diversity (FSD = 0.382) was the lowest in the three stand types, mainly due to its lower diversity in both vertical (FSDv = 0.369) and horizontal (FSDh = 0.562) structure than the two natural forest stands. The average number of tree species in the structural units was higher in natural forest than in plantation, with 4.23 in Quercus aliena var. acutiserrata forest, 4.09 in Pinus koraiensis forest, and 1.98 in Platycladus orientalis plantation. The number of tree species in a structural unit fully demonstrate species richness of the structural unit.   Conclusion  The integration of the three numbers including 4-variate distribution of stand spatial structure parameters, the number of tree species and number of forest layers in structure unit, lays the foundation for constructing a valid spatial structure diversity index for forest stands. The stand spatial structural diversity index (FSD), based on the concept of biodiversity, is not only a feasible quantitative expression of the 4-variate distribution of structural parameters, but also is an appropriate interpretation of the ecological significance of the 4-variate distribution of structural parameters, and a comprehensive scientific evaluation of the spatial structural diversity of the stand. The index is able to measure the difference of stand spatial structure diversity of different stand types.
Abstract:
Objective  Based on the optimal cutting age of Pinus tabulaeformis building materials, we start with density effect, which intending to explore the response mechanism of wood growth characteristics and soil physicochemical properties under different stand densities and identify the limiting factors affecting wood production. The results provide guidance for improving the cultivation technology and sustainable management of P.tabulaeformis building timber forest in Hebei province.   Method  The 50 a, 52 a and 56 a final felling age stands of P.tabulaeformis building forests in Pingquan city, Hebei Province were taken as research objects and divided into three density gradients: 450 ~ 750 plants/ha for low density, 750 ~ 1 050 plants/ha for medium density and 1 050 ~ 1 350 plants/ha for high density. The wood growth characteristics and soil physicochemical properties of three stand densities were studied. Pearson correlation analysis was conducted on each growth performance index and soil physicochemical properties. In addition, factor analysis method was used to calculate the comprehensive score and ranking of P. tabulaeformis construction timber stands of each density by combining the growth performance and soil quality, and to evaluate their sustainable management ability.   Result  (1) The wood output per unit of stand is not significantly affected by stand density, but decreased with the decrease of stand density. The wood output per unit of high density stand is the highest, which is 107.87 m3/ha. (2) The average timber output per wood and unit area tree trunk biomass of low density P. tabulaeformis building timber forest are 0.256 4 m3 and 148.02 t/ha, both of which are significantly higher than that of medium density and high density (P < 0.01), and more than double the medium density and high density. The percentage of single wood yield and trunk biomass of low density are 84.12% and 68.56%, which are both significantly higher than that of medium density and high density. (3) Density effect have significant effects on soil bulk density, non-capillary porosity and saturated water holding capacity (P < 0.01), and have significant effect on soil total porosity (P < 0.05). Among the chemical properties, only soil available potassiumis significantly affected (P < 0.01). (4) The output per unit area has no significant correlation with other indicators. There is a significant positive correlation between average wood output per tree and the proportion of trunk biomass (P < 0.01), and a negatively correlated with non-capillary porosity (P < 0.05). The percentage of trunk biomass is significantly positively correlated with soil bulk density (P < 0.05), negatively correlated with saturated water holding capacity and total porosity (P < 0.05), and negatively correlated with non-capillary porosity (P < 0.01). (5) The comprehensive quality of stand is highest at the density of 750 ~ 1 050 plants/ha, which is most conducive to the sustainable management of P.tabulaeformis building timber forest.   Conclusion  The trees in low density (450 ~ 750 plants/ha) are used to make large-diameter building frame materials, and the trees in medium and high density (750 ~ 1 350 plants/ha) are used to make small-diameter spliced materials and furniture, etc. Soil layer mainly affects the chemical properties of soil, while stand density mainly affects the physical properties of soil. There is no significant correlation between wood yield per unit and tree growth performance and soil physicochemical properties. The accumulation of trunk biomass can promote the increase of wood output per tree. The optimal reserve density for sustainable management of P.tabulaeformis building timber forest is 750 ~ 1 050 plants/ha.
Abstract:
Objective  The Yellow River Basin has a pivotal role in ecological protection. In order to effectively cope with the ecological problems caused by rapid urban development, this paper constructs an ecological spatial network for the Yellow River Basin to protect biodiversity and mitigate landscape pattern fragmentation.  Method  This paper takes the Yellow River Basin as the research object, finding an approach to identify its spatial ecological network. First, the ecological source sites were selected by comprehensively considering land-use data, perimeter of the ecological patch area, normalized difference vegetation index (NDVI), modified normalized difference water index (MNDWI) and mean patch fractal dimension; then, the minimum cumulative ecological resistance surface was constructed and potential ecological corridors and ecological nodes were extracted by GIS spatial analysis and MCR model algorithm. Finally, the spatial ecological network of the Yellow River Basin consisting of ecological source sites and potential ecological corridors was obtained. The robustness of the proposed network was analyzed.   Result  (1) The potential ecological network in the Yellow River Basin consisted of 294 ecological source sites and 369 potential ecological corridors. (2) The main types of land utilization were woodland, grassland and water, which were chiefly distributed in the northeast and southwest part, with some scattered distribution in the southeast part. (3) Ecological corridors were denser in the northeast and southwest part, with complex ecological spatial network structure and longer lengths between small ecological source sites, which played a key role in the ecological environment of the study area. (4) A total of 125 ecological nodes in the network were extracted and tested for recovery and connection robustness using simulated attacks. On the whole, the recovery robustness of ecological space network under random attack was better than that of malicious attack, the connection robustness increased greatly after attacking a certain number of nodes. And then the network structure collapsed.   Conclusion  Based on the MCR model, this paper constructs a potential ecological spatial network in the Yellow River Basin and analyzes its topology, which provides an important reference for optimizing the ecological spatial network and provides theoretical guidance for promoting the high-quality development and improving the ecological civilization in the Yellow River Basin of northern China.
Abstract:
Objective  BiVO4-CdS composite photocatalysts with the wood biomimetic micro-nanopore structure were prepared from wood processing residues. The wood template was used to form more heterojunction structures, improve the catalytic performance of the photocatalytic material and expand the application of BiVO4 in the treatment of wood dye wastewater.   Method  BiVO4-CdS composite photocatalysts were prepared by impregnation-calcination and chemical deposition using wood processing residues from three species of wood (fir, poplar, and balsa).   Result  All three BiVO4-CdS composite photocatalysts with wood biomimetic structures exhibited good adsorption-photocatalytic degradation of RhB. The lower-density balsa-wood BiVO4-CdS showed a high removal rate of RhB (29.26%) after reaching adsorption equilibrium; the degradation rate of RhB under visible light was 96.01% in 120 min, and its reaction rate was 6.69 and 3.37 times higher than that of BiVO4 and BiVO4-CdS without a template. After ten adsorption-photocatalytic degradation cycles, the balsa-wood BiVO4-CdS still achieved a degradation efficiency of over 85%.  Conclusion  The biomimetic structure of wood gives the composite photocatalyst a rich pore structure. The cavity wall structure in the low-density wood facilitated the catalyst to obtain a large specific surface area and stable pore structure after impregnation and calcination treatment. At the same time, it also promoted the formation of the BiVO4-CdS heterojunction structure, which accelerated the rapid adsorption and degradation of pollutant molecules during the photocatalytic reaction.
Abstract:
Objective  The method of constructing microcore germplasm was discussed to provide scientific basis for precise selection of hybrid parents or research materials of P. tomentosa, and to provide reference for other species to construct mini core germplasm.  Method  In this study, molecular genotypes of 272 P. tomentosa samples were detected by fluorescent SSR molecular markers. The contribution value of each sample to the overall genetic diversity was calculated and sorted from large to small. Then, the representativity of mini core germplasm was analyzed and the appropriate sampling proportion was determined by comparing the average effective number of alleles Ne, the average Shannon’s information index I, the average expected heterogenicity He and the average polymorphic information content PIC values obtained by sampling proportion of top 25%, 20%, 15%, 10%, 5%, 2.5%, 2% and 1.5%. Finally, t test was used for statistical verification. According to the band-shaped results of all SSR primers, fingerprints of each mini core germplasm were formed. According to the difference of fingerprint, the specific alleles were analyzed and excavated.  Result  When the sampling proportion gradually decreased from 25% to 2%, three important genetic diversity parameters, Ne, He and PIC, gradually reached the maximum value respectively, while I reached the maximum value when the sampling proportion was 10%. When the sampling ratio was 2%, the values of Ne, I, He and PIC were 3.513, 1.254, 0.643 and 0.5973, respectively, which were all greater than 2.075, 0.825, 0.432 and 0.364 of the original germplasm, indicating that we had effectively removed the genetic redundancy, and the constructed mini core germplasm had abundant genetic diversity. The t test results showed that there was no significant difference in genetic diversity between the constructed mini core germplasm and the original germplasm, which was reliable and representative and could be used as the mini core germplasm. The proportion of hybrid germplasm was more than 50% regardless of the sampling proportion of 10%, 5% or 2%. Sample 218 had a specific allele at locus 11, sample 261 had a specific allele at locus 16, and sample 263 had a specific allele at locus 7.   Conclusion  when the sampling ratio of mini core germplasm of poplar is 2%−10%, it is the most scientific, reliable, simple and efficient, among which the most accurate sampling ratio is 2%. If the number of germplasm resources is large, it can be appropriately reduced according to the genetic diversity, and on the contrary, it can be increased appropriately. It is suggested that when constructing core germplasm or mini core germplasm in the future, rather than grouping, each sample is firstly ranked from largest to smallest according to its contribution to overall genetic diversity. It is proved from the molecular level that hybrid germplasm plays an important role in the conservation of germplasm resources and the genetic breeding of trees. At the same time, this study also provides reference for the construction of microcore germplasm of similar species.
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Objective  The spatial distribution pattern of trees is important for evaluating whether the forest needs to be managed, and judging which distribution state (aggregated distribution, random distribution, or uniform distribution) of trees is a prerequisite for developing suitable management plans. Moderate and high severity forest fires can kill a large number of trees, and then change the distribution characteristics of stand diameter and the spatial distribution pattern of forest trees. We investigated natural larch (Larix gmelinii) forests in the Da’erbinhu National Forest Park one year following a mixed-severity wildfire.   Method  By comparing the distribution of stand diameter, the spatial distribution pattern of different types of trees, and their association, we analyzed the influence of the fire on the spatial distribution pattern of trees.   Result  The results showed that in high severity areas, the number of small living trees and the gathering radius of small dead trees were relatively small. Compared with the unburned plots, the medium living trees presented a clustered distribution at the medium scale in the burned areas. The middle trees and the small trees were associated in the moderate severity burned plots. The medium dead trees and the surrounding small dead trees were positively associated within a radius of 4 to 8 m, while the medium living trees and the surrounding small dead trees were negatively associated within a radius of 8 to 20 m.   Conclusion  The spatial pattern of trees and the association between trees of different sizes and different status are affected by the fire severity. Choosing suitable afforestation measures according to the aggregation scale of trees for different fire severity is of great significance to forest restoration after a fire. This study can provide a scientific basis for the protection and rational use of nature larch forests in the Great Xing’an Mountains.
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‘Jingzao 39’ is a new high-quality jujube variety, due to the lack of efficient regeneration system in vitro at present, limiting the cultivation of self-root seedlings and its seedling purity. In order to solve the problems of long homology verification cycle and low genetic transformation efficiency of jujube, different influencing factors of jujube leaf regeneration were explored in this study, in order to establish an efficient leaf regeneration system.Using the leaves of tissue cultured seedlings of ‘Jingzao 39’ as experimental materials, the effects of different inoculation methods, types of basic culture medium, types and concentration ratio of plant growth regulators on the direct induction of adventitious bud regeneration from detached leaves were studied. The results showed that the regeneration rate of the inoculation method with the leaves being placed upward was much higher than that of back up, which was the best placement method for the regeneration of adventitious buds from leaves of ‘Jingzao 39’; The effect of basic culture medium on leaf regeneration of ‘Jingzao 39’ was greater than that of plant growth regulator, and the optimal basic medium and plant growth regulator was 1/2 MS and cytokinin 6-BA, respectively. The optimal regeneration system for leaves of ‘Jingzao 39’ tissue cultured seedlings established in this study was 1/2 MS medium + 1.0 mg/L thiabenduron + 0.5 mg/L 6-BA + 0.2 mg/L NAA + 30 g/L maltose + 6 g/L agar, an average of 4.67 adventitious buds could be regenerated for each leaf. Then, the optimal propagation system of ‘Jingzao 39’ tissue culture seedlings was initially explored and established: MS + 20 g/L maltose + 6 g/L agar + 3.00 mg/L 6-BA + 0.10 mg/L NAA, with the branching rate up to 88%, and the average branches number of 2.76; and the most suitable rooting medium was: 1/2MS + 20 g/L sucrose + 8 g/L agar + 1.50 mg/L IBA + 0.30 mg/L NAA, with rooting rate of 90.91%, and the average root length up to 4.08 cm. The leaf regeneration efficiency of ‘Jingzao 39’ is greatly influenced by external factors, especially the basic medium type and inoculation method, and each factor does not play an independent role. This study established a complete cultivation system for the functional verification of interested gene with the leaves of ‘Jingzao 39’ as transgenic materials, and laid a foundation for accelerating the jujube research process.
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Objective  Adventitious roots induction is an important method for the propagation of superior clones of Cunninghamia lanceolata clones. Adventitious roots induction in C. lanceolata tissue culture is affected by many factors. But the key factors that play a leading role are still unclear. By comparing the influences of different culture conditions on the induction of C. lanceolata adventitious roots. This study aims to find out the most suitable culture factors for C.lanceolata rooting, laying a foundation for subsequent experiments and studies.  Method  Using C. lanceolata clone T-c22 as the experimental material, by changing the nutrient conditions, the types and concentrations of hormone, removing needle leaves from shoots, adding activated carbon to the medium, light conditions and different light quality and other different culture factors, and various indexes of C. lanceolata rooting were investigated and statistically analyzed, in order to study the influence of different culture factors and the interaction between different factors and light on the rooting of C. lanceolata.   Result  (1) The results showed that compared with darkness, light significantly increased the plant height, rooting rate, average root number and average root length of C. lanceolata shoots, and significantly inhibited the fresh root weight of C. lanceolata. (2) Both white light and red light can increase the rooting rate of C. lanceolata, reaching 100%. White light can significantly increase the number of roots of C. lanceolata. Both red light and blue light can significantly reduce the root length of C. lanceolata. And they can significantly increase the plant height of plantlets of C. lanceolata. (3) Adding IBA and NAA single hormone significantly increased the plant height, average number of roots, average root length, root fresh weight and root dry weight of C. lanceolata. The interaction of light and a single hormone significantly increased the average root number and average root length.(4) The medium containing appropriate nutrients will significantly increase the rooting rate, number of roots, average root length, average fresh root weight and average root dry weight of C. lanceolata. The interaction of light and the nutrition significantly increase the plant height and average root length of C. lanceolata. (5) Removal of needles significantly increased the height of plantlets, the average root length and the average dry weight of roots.The interaction of light and removing needle leaves from shoots had no significant effect on the induction of adventitious roots of C. lanceolata. (6) Activated carbon significantly reduced the rooting rate, number of roots, fresh root weight and root dry weight of C. lanceolata plantlets. The interaction of activated carbon and light significantly reduced the rooting rate and average root length of C. lanceolata.  Conclusion  In this study, the importance order of factors affecting rooting of T-c22 clones of C. lanceolata was as follows: nutrients > species and concentration of plant growth regulators > different light quality > light duration and the interaction between light and other factors > whether or not to remove needles and activated carbon. The optimal medium for rooting of T-c22 clones of C.lanceolata was 1/2MS + NAA0.5 mg/L + IBA 0.5 mg/L. The optimal rooting conditions for C.lanceolata were the addition of appropriate nutrients, the appropriate concentration of plant growth regulator (NAA0.5 mg/L), the removal of some needles and the treatment of red light (16 h/day).
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Objective  Greenspace is the ecological foundation of urban and rural development, and a good greenspace system is an important guarantee for coordinating urban development and nature conservation. Comprehensive measurement and investigation of the spatio-temporal evolution pattern of city-wide greenspace in the lower reaches of the Yellow River can help the planning for the construction of ecological corridors in the lower reaches and ecological improvement in the floodplain.   Methods  Four cities in the lower reaches of the Yellow River, Jinan, Heze, Zhengzhou, and Xinxiang, were used as the study objects, and 1990, 2000, 2010, and 2020 were taken into account. Using vegetation cover density and the secondary classification of land use, the city-wide green space types are classified, and then the transfer matrix, landscape pattern index, urban-to-rural trajectory and Geo-detector are used to conduct quantitative research on the spatio-temporal patterns and mechanism of city-wide evolution greenspace.   Results  (1) During the 30-year period, the total green space in the study area transferred 3 223 km2 to non-vegetation, and 1 181 km2 to various types of green space from non-vegetation; 739 km2 of green space were converted to each other, including 508 km2 from higher to lower density, and 231 km2 from lower to higher density. (2) The decrease of PLAND and AWMSI of sparse greenspace, the decrease of NP of all kinds of green space, and the increase of MPS and Connect are the general rules of landscape pattern index. (3) the urban-to-rural trajectory of spares greenspace changes significantly in time series, while the dense and medium-dense greenspace is relatively fixed; (4) the influence of natural environmental factors on the geographical distribution of greenspace in Jinan, Zhengzhou and Xinxiang is dominant, and the cumulative influence of socio-economic factors in each city increases 3.1%−8.4%, showing an increasingly obvious non-linear enhancement with natural environmental factors.   Conclusion  During the 30 years, the total amount of regional green space is lost, and the internal transfer of green space is mainly from higher density to lower density, with more transfers along the edges of built-up areas and along the wide floodplain; the overall trend of landscape pattern changes from obvious fluctuation to nearly stable, from fragmentation and dispersion to integration and connectivity, and the improvement trend is more obvious in regional central cities; the urban-to-rural trajectory characteristics differ greatly between cities and greenspace types; the synergistic effect between influencing factors is gradually increasing, and greenspace gradually became the result of natural-social interconfiguration. In the future, the city-wide greenspace should be transformed from a “barrier” to a “hub” according to the needs of the city.
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Objectives  The class Ⅲ peroxidase is a group of plant-specific oxidoreductases, and plays an important role in plant development and stress response. This paper presented a detailed overview of evolutionary and expression of olive class Ⅲ PRX gene family, aiming to provide a reference for olive molecular breeding in the future.   Methods  With some bioinformatic tools, we finished the identification of the olive class Ⅲ PRX genes, completed the analyses of the phylogenetic relationships, gene mapping on the chromosomes, pairs of duplicates, motifs, gene structure, cis-acting elements and gene expression in different tissues or biotic stresses, and did a verification of RNA-seq by RT-qPCR.   Results  (1) 106 OePRX were obtained, and classified into 14 Groups based on the phylogeny with AtPRX and PtPRX. (2) OePRX were unevenly located on 23 chromosomes.The segmental duplication was a maining force driving in the expansion of OePRX gene family, and compared with AtPRX, OePRX had a closer relationship with PtPRX. (3) The characterization of pI, MW, motifs, gene structure, signal peptide, and expression in different tissue had the expected group-conserved patterns.The promoters of OePRX contained a variety of development and harmone elements; 38% of OePRX genes was differentially expressed in heat, drought and waterlogged stress.   Conclusions  The differential expansion and differential expression may imply flexibility in neofunctionalization of duplicated class Ⅲ peroxidase genes that is of adaptive significance to the strong resistance of olive to a diversity of conditions, hence contributing to the importance of olive as a Mediterranean Basin staple food.
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Objectives  Although high thermal conductivity fillers can improve the heat storage and release rate of wood-based phase change heat storage composite materials. The agglomeration of nanoparticles is not conducive to their uniform dispersion in the material. The purpose of this paper is to use the solution reduction method to in-situ generate monodisperse copper particles in the balsa wood (Ochroma pyramidale) matrix from the inside to out, so as to develop a green and economic way to improve the heat storage and release properties of phase change heat storage wood-based composite materials.   Methods  Firstly, the balsa wood was delignified with acid sodium chlorite solution to improve the packaging efficiency of phase change materials. Then, the monodisperse Cu particles were prepared by the solution reduction method in delignified balsa wood with CuSO4 solution and ascorbic acid solution by cyclic reaction, and the paraffin wax (PW) was added to the wood-based composite by vacuum impregnation method. Field emission electron microscope (SEM), infrared spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimeter (DSC), thermal conductivity tester and temperature inspection instrument were used to evaluate the microstructure, crystallization, chemical structure and heat storage and release properties of the materials.   Result  After delignification, the encapsulation efficiency of balsa wood increased from 64.9% to 82.6%. After the reduction of Cu2+ by ascorbic acid, Cu was produced in-situ in the balsa wood matrix. However, if the number of cycles is too small, Cu can not be evenly distributed in the wood matrix, and if the number of cycles is too large, the packaging effect of balsa wood on phase change materials will be excessively affected. The three cycles are the most appropriate. The thermal conductivity of the composite phase change heat storage material prepared by this method is increased by 1.76 times, the melting and solidification latent heat are as high as 143.7 and 142.9 J/g respectively, and the heat storage and heat release time are shortened by 23.7% and 32.6% respectively, showing a better potential for temperature regulation.   Conclusion  The solution reduction method can effectively prepare Cu particles uniformly in the balsa wood matrix, and the wood-based composite phase change heat storage material with Cu particles prepared by three cycles to enhance heat conduction has good heat storage and release performance.
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Objective  A scalable altimeter was developed to solve the limited landing range of measuring tree height based on trigonometric function and to realize accuracy measurement of vertical and inclined growth tree height.   Method  Based on principle of draw-wire sensor measuring tree height, the scalable altimeter was developed, of which main structure contains optical electricity encoder , brushless DC motor, coil and rope. The tree height measured by linen tape was taken as true value. A total of 20 vertical growth trees and 11 inclined growth trees were measured by scalable altimeter, Blume-Leiss altimeter and forest compass to compare the measurement precision, variance and t result respectively. The tree height of No. 8 sample (vertical growth tree) and No. 26 sample (inclined growth tree) were measured continuously to test the measurement accuracy by 6 times.   Result  The results demonstrated that the precision of scalable altimeter in measuring vertical and inclined growth tree height was 0.034 and 0.028 m. The variance of scalable altimeter in measuring vertical and inclined growth tree height was 5.60 and 9.94. The accuracy of scalable altimeter in measuring vertical and inclined growth tree height was 0.028 and 0.015 m. The precision of Blume-Leiss altimeter in measuring vertical and inclined growth tree height was 0.154 and 0.267 m. The variance of Blume-Leiss altimeter in measuring vertical and inclined growth tree height was 5.76 and 10.00. The accuracy of Blume-Leiss altimeter in measuring vertical and inclined growth tree height was 0.150 and 0.125 m. The precision of forest compass in measuring vertical and inclined growth tree height was 0.059 and 0.183 m. The variance of forest compass in measuring vertical and inclined growth tree height was5.66 and 10.02. The accuracy of forest compass in measuring vertical and inclined growth tree height was0.056 and 0.066 m.   Conclusion  The measurement results of scalable altimeter had better measuring precision than Blume-Leiss altimeter and forest compass. The development of scalable altimeter would not only solve the problem of disconnection between field investigation and internal entry, but also meet the requirements of standing tree height measurement in national continuous forest inventory and forest management inventory effectively.
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Objective  To investigate changes in the crystalline structure of cellulose in wood cell wall induced by water, matrix (lignin and hemicellulose) removals at various degrees by mild method were conducted, and effects on cellulose crystalline structure as well as its interaction with matrix under typical water states (oven-dried, approximate fiber saturation point and water-saturated state) were discussed.   Method  Poplar (Populus euromericans) wood was chosen as the research object. Specimens of chips (20 mm (longitudinal) × 3 mm (radial) × 20 mm (tangential)) were subjected to matrix removal at room temperature, where CH3COOH/NaClO2 solution was used to remove lignin, and NaOH was used to remove hemicellulose, to obtain samples at different removal ratios of lignin, hemicellulose and both matrix. Water states of treated and untreated specimens were conditioned to oven-dried, approximate fiber saturation point and water-saturated state, and X-ray diffraction technology was applied to detect the diffraction peak positions (2θ) of (200), (1-10) and (110) for analyzing the lattice spacing.   Result  The (200) peaks of the oven-dried specimens were changed when the matrix was removed, and the (200) lattice spacing tended to decrease with the increase of matrix removal ratio; the (200) lattice spacing of each group of specimens reduced with increasing water content, and for the specimens removed lignin or hemicellulose, the reduction in lattice spacing at the approximate fiber saturation point accounted for a larger percentage of that at the saturated state; with an increase in water content of the specimens, (1-10) and (110) peaks tended to separate.   Conclusions  (1) At oven-dried condition, cell wall matrix of wood exerted tensile stress on the cellulose; (2) Change in physical and chemical environments of the wood cell wall affected the interaction between matrix and water. The swelling of matrix due to water entering caused tension on the cellulose crystal structure to release, which mainly induced by the water in cell wall and acted primarily on the (200) lattice planes.
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Objective  Explore the relationship between the meiosis process of Cunninghamia lanceolata(Chinese fir) microspore mother cell and the external morphological change of male cone, so as to provide references for further research on reproductive biology of C. lanceolata.   Method  We selected the male cones of C. lanceolata as the material, and studied the process of meiosis of C. lanceolata microspore mother cell and development of male cones using the digital camera, stereoscope and the Acetate Magenta Staining Method.   Results  The male cones of C.lanceolata borne on the tips of new branches and are coated with bud scales. With the meiosis process of C. lanceolata microspore mother cells to carry out, the bud scales of male cone gradually open, the volume of the microsporophyll increased and gradually elongates beyond the bud scales eventually squeezing the bud scales of male cone to falling off. In addition, the color and size of the microsporophyll also vary markedly: the color changing from emerald green, yellow green, yellow brown, and finally to reddish brown; its length ranges from 3.278 mm to 5.229 mm, and diameter ranges from 2.626 mm to 3.868 mm. When observing the meiosis process of C. lanceolata, it was found that microspore mother cells had abnormal chromosome behavior, meiotic metaphase Ⅰ lagging chromosomes, anaphase Ⅰ anaphase Ⅱ have dissynchrony splitting, and the unequal division, such as dyad, triads were observed in the tetrad stage. The development of male cones in different locations was not synchronous; even within the same male cone, the meiosis process of microspore mother cell in different microsporophylls and same microsporophylls was as also different, the whole meiosis process lasts about three days.   Conclusion  The meiosis process of C. lanceolata microspore mother cell is closely related to the change in external morphology and the microsporophyll color and size of male cone, and there are chromosomal abnormalities in its process of meiosis.
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Objective  Utilizing laser pairs LiDAR with high scanning frequency to assist individual tree localization in process of ground verification, quickly and accurately correspond to the plots observation and verification data, and provide technical support for precision forestry.   Methods  Taking the planted forest in Sun Yat-sen University as the research object, with the help of laser pairs LiDAR with high scanning frequency (defined as monitor LiDAR) to assist tree localization during the ground verification of individual tree inventory, firstly solving the problem of registration with backpack and monitoring point clouds, and obtain the base map of individual tree localization in sample plots; Then, Based on the method of background difference, the monitor LiDAR is used to track the dynamic target in real time and obtain its positions. Combined with the individual tree localization base map, the position of the individual tree measured by the ground investigator is judged indirectly, so as to realize the correspondence between the plots observation and the validation data.   Results  Using our method to register the backpack and monitor point clouds, RMSE of coarse registration is all less than 0.2 m, and which is less than the minimum spacing of standing trees and meets the requirements of corresponding; Using the dynamic target tracking and corresponding method in this paper, taking the positions of investigators as seed points, the serial number of tree which is closest to the seed points in the base map is obtained through the nearest search, so as to realize the data correspondence , its accuracy is higher than 95%, the average processing time of per frame is less than 0.1 s, which meets the requirements of real-time.   Conclusion  Our method proposed in this paper uses LiDAR to assist tree localization in the process of ground verification, which can improve the accuracy and efficiency of correspondence to plots observation results and verification data, and helps to promote the development of precision forestry inventory technology.
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Lignocellulosic fiber is composed of cellulose, hemicelluloses and lignin, which are entangled together to form a 3D network system. The physical and chemical interactions and ordered assembly of these macromolecular has been proved to contribute to the optimal mechanical properties of plant fiber. In the present work, the micromechanical features of cellulose, hemicelluloses and lignin was summarized, while the macromolecular interactions between cellulose-hemicelluloses, cellulose-lignin, hemicelluloses-lignin as well as the cellulose molecular conformation modulated orientation correlation among these macromolecular was reviewed. Furthermore, the characteristics among light microscopy, SEM, TEM, AFM, FT-IR microscopy, polarized laser confocal Raman microscopy, sum frequency generation spectroscopy and XRD techniques are compared. Especially, the application of molecular spectroscopy imaging approaches in revealing the macromolecular orientation of lignocellulosic fiber was discussed. Finally, the further research in macromolecular orientation was listed. Characterizing the cellulose supramolecular, interlinkage pattern of cell wall components, the effect of cellulose configuration on the ordered assembly of hemicelluloses glycosidic bonds and lignin aromatic rings. Reavling the change of microfibrils aggregate structure, orientation and micromechanics during cell wall development. Non-destructive and quantitative 3D imaging of macromolecular orientation of lignocellulosic fiber. Reconstruction of softwood, hardwood and herbaceous species cell wall skeleton based on molecular structure characterization, molecular simulation, and 3D imaging data.
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Objective  Pinus sibirica is a precious tree species with excellent wood and fruit. It is mainly distributed in the cold and temperate zone of Russia, with rich intraspecific variation. The introduction experiments of different provenances were carried out to select excellent provenances, so as to provide basis for large-scale introduction and afforestation in the later stage.   Method  According to the provenance division of the tree species, seeds were collected at 7 seed collection points in the main provenance area. The seedling raising and afforestation were designed according to the completely randomized block experiment. We investigated the tree height of 7 years old and 9 ~ 18 years old and the DBH of 7, 15 and 18 years old. What’s more, the 18-year-old preservation rate was also investigated. For the investigated characters, the analysis of variance and multiple comparative analysis among provenances were carried out. The generalized heritability of each character was estimated. The correlation analysis between the characters and the temperature and precipitation factors of afforestation site was carried out, and the tree height growth curve model fitting analysis of different provenances was carried out.   Results  The results of variance analysis showed that the differences of growth traits among various provenances mostly reached a very significant level, and the coefficient of variation was between 17% ~ 65%, mostly about 25%. The coefficient of variation of tree height traits basically showed a trend of gradually decreasing with the increase of age. The broad heritability of all traits was high, most of which were more than 70%. The correlation analysis between the high growth in the current year and the temperature and precipitation of the afforestation site shows that the temperature of the afforestation site is the main factor affecting the high growth. The higher annual average temperature, March and July average temperature not only promote the high growth of Pinus sibirica in the current year, but also significantly promote the growth in the second year. The fitting analysis of tree height curve model and multiple comparative analysis showed that among the introduced Pinus sibirica provenances, Tomsk provenance and Ulan ude provenance were outstanding and were determined as excellent provenances. The genetic gains of tree height and DBH were 6.73% and 3.09%, 4.68% and 9.50% respectively.   Conclusion  The growth characters of Pinus sibirica provenances showed obvious variation, The temperature of afforestation site is the main factor affecting high growth. Higher temperature is not only beneficial to high growth in the current year, but also significantly promotes high growth in the second year; Based on the tree height curves and multiple comparisons of various provenances, Tomsk provenance and Ulan ude provenance were selected as excellent provenances.
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Objective  As a newly developed woody oil tree species, Idesia polycarpa has broad development prospects. Idesia polycarpa “Exuan 1”, as a newly identified new variety, has the characteristics of high and stable yield, strong adaptability and so on. The demand for high-quality seedlings of Idesia polycarpa “Exuan 1” is increasing, so it is urgent to build an efficient breeding system to meet the wide application of Idesia polycarpa “Exuan 1” in the industry.  Method  Based on the optimization of explant disinfection method, hormone combination of adventitious bud induction medium, hormone combination of adventitious bud proliferation medium and hormone combination of tissue culture seedling rooting medium, tissue culture technology was used to construct tissue culture and breeding system of Idesia polycarpa “Exuan 1”. In this study, we systematically studied the disinfection methods of the explants of Idesia polycarpa “Exuan 1”and the effects of plant hormones on the process of bud induction, proliferation and rooting.  Result  (1) Using 75% ethanol treatment for 30 s combined with 0.1% HgCl2 treatment for 8 min was the best disinfection method for the explants of Idesia polycarpa “Exuan 1”. (2) 1/2MS + 0.03 mg/L TDZ + 1.5 mg/L 6-BA + 0.05 mg/L NAA medium combination was suitable for adventitious bud induction of Idesia polycarpa “Exuan 1”. (3) The combination of 1/2MS + 0.2 mg/L TDZ + 2.0 mg/L 6-BA + 0.05 mg/L NAA medium was suitable for adventitious bud proliferation of tissue culture of Idesia polycarpa “Exuan 1”. (4) The combination of 1/2ms + 0.3 mg/L NAA + 0.5 mg/L IAA medium was suitable for rooting induction of tissue culture seedlings of Idesia polycarpa “Exuan 1”. Under this condition, the rooting rate of tissue culture seedlings reached 98%.  Conclusion  In this study, we constructed a rapid propagation system of “Exuan 1”, which laid a foundation for the popularization and application of “Exuan 1” and further research on Idesia polycarpa. at the molecular level.
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Objective  Glutathione peroxidase (GPX) is one of the key enzymes in the plant's enzymatic active oxygen scavenging mechanism.Conducting enzymatic characteristics and stress resistance research on Larix kaempferi GPX can supply and improve genetic resources and provide theoretical basis for exploring the molecular mechanism of glutathione peroxidase stress resistance.   Method  The glutathione peroxidase genes were cloned using the stem tissue of Larix kaempferi as a template. In this study, bioinformatics analysis and subcellular localization research were conducted. The GPXs were induced and purified for in vitro enzymatic assays, and verified to have the stress resistance through spotting experiment and growth curve experiment.   Result  Two GPX genes were cloned from the stem of Larix kaempferi, named LkGPX2 and LkGPX3, both of them contained complete characteristic conserved motifs. LkGPXs were grouped together with the PmGPX and PeGPX in a phylogenetic tree, which were stress-resistant. Subcellular localization showed that both LkGPX2 and LkGPX3 proteins were localized in the nucleus and cytoplasm. Using thioredoxin (Trx) as an electron donor for in vitro enzymatic activity, LkGPX2 and LkGPX3 had catalytic activity on H2O2, t-BHP and Cum-OOH. The catalytic activities of LkGPX2 were (0.4017 ± 0.037) U/mg, (0.4240 ± 0.018) U/mg, (0.4249 ± 0.009) U/mg, and the catalytic activities of LkGPX3 for the three substrates were (0.3973 ± 0.027) U/mg, (0.4491 ± 0.028) U/mg, (0.4074 ± 0.021) U/mg. Moreover, the results of stress treatment experiment indicated that LkGPX2 and LkGPX3 could improve the tolerance of Escherichia coli to simulated drought stress and salt stress.   Conclusion  Larix kaempferi glutathione peroxidase (GPX) is capable of scavenging active oxygen as well as responding to abiotic stresses.
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Objective  The vast forest zone in Northeast China is an important ecological barrier of China. In this paper, change of growing season NDVI and its response to climate change for forest in Northeast China was studied in order to provide scientific basis and guidance for forestry establishment and protection in Northeast China under the background of diurnal asymmetric warming.   Method  Based on the SPOT Vegetation NDVI, different vegetation types’ spatial distribution, monthly precipitation and monthly temperature data from 2000 to 2019, using trend analysis, Hurst index and coefficient correlation analysis method, this paper investigate the spatial and temporal change character of growing season NDVI and its response to climate change for forest in Northeast China under the background of day and night asymmetric increase.   Result  （1）In recent 20 years, growing season NDVI for forest in Northeast China generally showed an increasing trend, with the growth rate of 0.035/10 a. The mixed forest showed the highest increase rate, reached 0.037/10 a, the broad-forest showed the smallest increase rate. The growing season NDVI for forest in Northeast China mainly reveals improvement, which accounted for 55.59% of the total forest area, and 43.84% is basically unchanged. Only 0.57% is degraded. （2）For the whole growing season, NDVI is significantly affected by minimum temperature and precipitation, and is weakly related to maximum temperature, at the same time, minimum temperature and precipitation in the growing season show an obvious increasing trend, and maximum temperature has no obvious change, which contributed the increase of NDVI in northeast forest during growing season obviously under the background of diurnal asymmetric warming. Different forest types have different responses character: among the three forest types, coniferous forest growth is mainly affected by minimum temperature; broad-leaved forest growth is mainly affected by precipitation and minimum temperature; mixed forest growth is most sensitive to precipitation. （3）For the monthly response character, the NDVI in the early growing season (April- May) is mainly affected by the maximum temperature and the minimum temperature, and the temperature sensitivity decreases gradually with the increase of temperature. At the end of the growing season (September- October), it is jointly controlled by the minimum temperature and precipitation, and the precipitation sensitivity is higher in the mid growing season (June- August). The sensitivity of NDVI to precipitation and temperature shows obvious time lag character. （4）Future trend analysis indicate that the forest in Northeast China will change from improvement to degradation, around 71.94% of all forest will at risk of degradation, especially in areas with severe climate change regions.   Conclusion  Diurnal asymmetric warming and differential response of NDVI to the maximum and minimum temperature lead to the asymmetric effect of daytime and nighttime temperature on the change of NDVI for forest in Northeast China, from 2000 to 2019, the growing season NDVI for forest in Northeast China has been increasing, but will be at risk of degradation in future.
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Objective  The research on the relationship between airborne pollen concentration and vegetation spatial structure which conclusion is to summarize the vegetation spatial structure under different pollen concentration section would be applied to the design and transformation of plant community. The conclusion can provide data support for the design, construction and transformation of urban green space in Beijing and has practical guiding significance for the construction of urban green space environment.   Method  The research applied the Durham pollen collector to monitor the airborne pollen concentration of 92 sampling points in Beijing from April 3, 2021 to April 9, 2021. The vegetation spaces with different pollen concentrations were classified by CART which obtain the vegetation spatial structure model maps corresponding to high, medium and low pollen concentration sections.   Result  (1) Coverage of arbors is the main control index to distinguish the pollen concentration of different squares. And the relationship between coverage of arbors with pollen concentration is not a single linearity but a certain degree of volatility. When the coverage of arbors is between 0.698 and 0.777, the pollen concentration is the lowest which predicted value is 74 pcs/1000 mm2. When the coverage of arbors is greater than 0.777, the pollen concentration is the largest which predicted value is 285 pcs/1000 mm2. When the coverage of arbors is between 0.600 and 0.698, the predicted value of pollen concentration is 207 pcs/1000 mm2. When the coverage of arbors is less than 0.777, the predicted value of pollen concentration is 133 pcs/1000 mm2. (2) In addition to the coverage of arbors, the control indicators for different pollen concentrations of different vegetation space include the average height of shrubs, average height of arbors, average height of ground cover plant, average height under branches of arbors, structure types of plant communities, percentage of arbors and three-dimensional green quantity of ground cover plant, etc. (3) The vegetation spatial structure with low pollen concentration is mainly with high trees in the upper layer and low shrubs in the middle and lower layer. The vegetation type is mainly large trees with high branch points. There are two main types of the vegetation spatial structure with high pollen concentration. One is that when the coverage of upper trees is lower, the vegetation in the middle and lower layers is dense, the other is that the coverage of upper trees is very high, and the vegetation community is very dense. The vegetation types are mainly evergreen trees, deciduous trees with dense canopy, and shrubs with rich branches.   Conclusion  The scientific basis for the planting and optimization of airborne pollen sensitized plants was provided. For new urban green space, the sensitized plants should be used in the vegetation community with the spatial structure similar to the vegetation spatial structure with high pollen concentration. For the established vegetation community containing airborne pollen sensitized plants, the vegetation space structure originally with low pollen concentration could be transformed into the vegetation space structure with high pollen concentration by increasing plants. The pollen should be retained and settled in the vegetation space as far as possible, so the amount of pollen dispersed into the city would be reduced and the health threat of airborne pollen sensitized plants to allergic people would be alleviated.
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Objectives  Carbon (C) and nitrogen (N) elements are crucial for plant growth and development, especially in extremely arid inland river basins. Plants in different functional groups would show different stoichiometric characteristics due to the variations in requirements for soil water and nutrients. It is of great significance to explore stoichiometric characteristics among different plant functional groups in the lower reaches of the Heihe River, as well as their nutrient content responses to groundwater fluctuation, aiming to further understand desert ecosystems under the background of global climate change.   Methods  In the lower reaches of the Heihe River, a total of 22 sampling sites were set up according to the vertical distance between vegetation and river. Correlation analysis and variation partition analysis (VPA) were applied to determine the relationship between plant stoichiometry and environmental factors among plant functional groups, respectively.   Result  The results showed that the average C and N contents in leaves and fine roots in the Lower Reaches of Heihe River were 408.53, 16.30, 500.34 and 11.81 mg/g, respectively. The average C∶N ratio were 30.74 and 49.48, respectively. Compared with global and regional studies, it was found plants in the lower reaches of the Heihe River had higher C content, lower N content and higher C∶N. Different from herbaceous plants, the C content, N content and C∶N of woody plants were significantly correlated with the changes of groundwater depth. We found that the stoichiometric characteristics of plant carbon and nitrogen in the lower reaches of the Heihe River were significantly correlated with soil properties. The groundwater and soil variables jointly explained 53%−75% of the variation in woody plant stoichiometry. Additionally, soil pH and soil electrical conductivity explained 20% of the variation in herbaceous plant stoichiometry.   Conclusion  Our study found groundwater was the key factor affecting the carbon and nitrogen stoichiometry of woody plants under extreme drought and saline-alkali environment, and the carbon and nitrogen stoichiometry of herbaceous plants was mainly influenced by soil pH and soil electrical conductivity.
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Objective  Disturbance and nitrogen deposition are important environmental factors that influence plant invasion. At present, studies on the synergistic effects of disturbance and nitrogen deposition on plant communities in wetland invaded by Alternanthera philoxeroides are relatively lacking. This study is to explore the short-term effects of disturbance, nitrogen deposition and wetland plant communities on A. philoxeroides invasion, which established a strong theoretical support and practical foundatio for the physical control of A. philoxeroides and the restoration and reconstruction of wetland vegetation.   Method  In this study, invasive plant A. philoxeroides and four wetland plant communities, including Myriophyllum aquaticum, Scirpus validus, Iris wilsonii and Lythrum salicaria were selected as the subjects. And three-factor control experiments were designed for invasive plant disturbance (no disturbance, simulated herbivory, mowing), nitrogen deposition (no nitrogen addition and with nitrogen addition), and native plant competition or not (only A. philoxeroides modes, and A. philoxeroides and wetland plant communities composed by 4 plant species).   Result  Simulated herbivory and mowing had significantly reduced the growth and reproduction traits including the relative growth rate basing on biomass, plant height and node number of A. philoxeroides. The structural equation model showed that the influence coefficients of simulated herbivory and mowing were −0.58 and −0.98, respectively. And mowing has a greater impact than simulated herbivory. The growth rate of A. philoxeroides was negative under mowing, the compensation index of three traits was significantly lower than those of simulated herbivory treatment, but there was insufficient compensation. Furthermore, the wetland plant community significantly reduced the indexes including root, leaf, total biomass, leaf number, stem length and branch number of A. philoxeroides. However, nitrogen deposition only significantly affected the compensation coefficient of A. philoxeroides branching. Except for leaf number and branching compensation coefficient, there was no significant interaction between disturbance and nitrogen deposition on plant communities in the wetland invaded by A. philoxeroides.   Conclusion  Simulated herbivory and mowing were not conducive to the invasion of A. philoxeroides to a certain extent, and had a strong inhibitory effect on the growth and recovery of A. philoxeroides with the increase of interference intensity. Nitrogen deposition did not significantly affect the composite indicator of A. philoxeroides. The local wetland plant community can inhibit the invasion of A. philoxeroides to a certain extent. Combined of the disturbance and nitrogen deposition only had a significant effect on the compensation coefficient of number of leaves and number of ramets, but had no significant effect on the wetland plant community invaded by A. philoxeroides.
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Objective   Saihanba Mechanical Forest Farm is the largest plantation Forest Farm in the world, it has been awarded the “Earth Guardian Award” by the United Nations in 2017. Thus, it is particularly important to scientifically evaluate the contribution of afforestation to the restoration of Saihanba forest ecological function. This study aims to analyze the current situation of Saihanba forest ecological function from different aspects and provide a theoretical basis for future forest management.   Method   The ecological function grade of various forests in Beimandian Forest Farm in Saihanba has been evaluated based on the technical specification for National Forest Resources Planning, Design and Investigation (GB/T 26424−2010) with 8 evaluation factors of forest volum, forest community structure, species structure, total vegetation coverage, canopy density, mean tree height and litter thickness.   Result   The forest ecological function index of Beimandian Forest Farm of Saihanba was 0.488, in which the stand with good ecological function grade accounted for 3.8%, the stand with medium ecological function grade accounted for 52.7%, the stand with bad ecological function grade accounted for 42.4% and the stand with worse ecological function accounted for 1.1%. The ecological function index of different stand origins was as follows: natural forest (0.545) > planted forest (0.474). The ecological function index of different forest types was as follows: mixed forest of needleleaf and broadleaf species (0.710) > mixed forest of broadleaf species (0.617) > secondary forest of natural platyphylla (0.535) > mixed forest of needleleaf species (0.487) > Larix principis-rupprechtii plantation (0.478) > Picea asperata plantation (0.443) > Pinus sylvestris var. mongolica plantation (0.429). The ecological function index of different age groups was as follows: over-mature forest (0.588) > middling forest (0.512) > near-mature forest (0.509) > mature forest (0.504) > young forest (0.434).   Conclusion   The forest ecological function of Beimandian Forest Farm has significantly improved after nearly 60 years of afforestation projects, which compared with sandy wasteland. However, the ecological function of artificial forests still has great space for improvement. The artificial forests should be subject to necessary management combined with the concept of near natural management.
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Objective  To reveal the influence rule of forest type and light-felling intensity on the carbon source and sink of Korean pine forests by planting conifer and reserving broad-leaved tree (PCRBT), and to provide basis for the restoration of zonal climax vegetation broad-leaved Korean pine forest.   Method  The annual net carbon sequestration of vegetation, net carbon emission (CH4, CO2) of soil heterotrophic respiration with related environmental factors(temperature, water content of soil, organic carbon, total nitrogen and so on) under different light-felling intensity(Control, Low-intensity LF-1/7, Heavy-intensity LF-1/3) were measured simultaneously by Static chamber-gas chromatograph and relative growth equation in three types of Korean pine forests by PCRB (Mongolian oak-Korean pine forest and white birch-Korean pine forest, which Korean pine planted under secondary crown for 25 ~ 35 years and light-felling for 25 ~ 30 years) in temperate in Xiaoxing’an Mountains., in order to reveal the influence of forest type and light-felling intensity on the carbon source/sink of Korean pine forest according to the net carbon balance of the ecosystem.   Results  (1) The annual average efflux of soil CO2 (159.94 ~ 207.43 mg/(m2·h)) in three forest types, were influenced by both the intensity of light-felling (heavy-intensity LF significantly increased 18.9% from Mongolian oak-Korean pine forest), and the forest type (control was white birch-Korean pine forest significantly higher than aspen-Korean pine forest and Mongolian oak-Korean pine forest, low, and heavy LF had no significant impacts among three forest types); low, and heavy LF had no significant impacts on the annual average flux of soil CH4 uptake (−0.047 ~ −0.028 mg/(m2·h)) from three forest types but white birch-Korean pine forest and aspen-Korean pine forest has significantly higher than Mongolian oak-Korean pine forest. (2) Low, and heavy-intensity LF made the annual net carbon sequestration of vegetation (1.66 ~ 3.99 t/(ha·year)) from three forest types had no significant effect, but white birch-Korean pine forest significantly higher (105.4% ~ 124.1% and 31.0% ~ 32.6%) than aspen-Korean pine forest and Mongolian oak-Korean pine forest , aspen-Korean pine forest has significantly higher(55.7% ~ 71.1%) than Mongolian oak-Korean pine forest. (3) Low-intensity LF had no significant impacts on carbon sink in Mongolian oak-Korean pine forest (−1.93 ~ −1.12 t/(ha·year)) and aspen-Korean pine forest (−0.65 ~ −1.03 t/(ha·year)) and White birch-Korean pine forest (−0.13 ~ 0.46 t/(ha·year)), but the level and direction of the effect of heavy-intensity LF were closely related to the forest type, Mongolian oak-Korean pine forest has significantly increased about 72.3%, White birch-Korean pine forest converted into carbon source, aspen-Korean pine forest has slightly increased carbon source.  Conclusion  Therefore, considering the maintenance of forest carbon sink in Korean pine forests by planting conifer and reserving broad-leaved tree, the faster recovering White birch-Korean pine forest and aspen-Korean pine forest was more appropriate to take heavy-intensity LF, while the slower recovering Mongolian oak-Korean pine forest are suitable to be low-intensity LF.
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Objective  We analyzed the characteristics of JAZ gene family in Pinus tabuliformis and its functional domain of interaction with gibberellin negative regulator DELLA protein, in order to lay a foundation for the analysis of jasmonic acid (JA) -gibberellin (GA) mediated growth/defense balance strategy in conifers with JAZ-DELLA as the core module.   Method  This study screened and identified all JAZ genes based on the whole genome data of Pinus tabuliformis, and analyzed the basic characteristics of P. tabuliformis JAZ gene family; At the same time, a phylogenetic tree of multi-species JAZ gene family was constructed to parsed the characteristics of P. tabuliformis JAZ gene family in the phylogenetic process. Furthermore, the functional domain of interaction between P. tabuliformis JAZ gene family and DELLA protein was identified by yeast two-hybrid technique.   Result  The results show that: there were 53 JAZ genes in Pinus tabuliformis, and the JAZ gene family of P. tabuliformis not only had TIFY and Jas conserved structures, but also evolved more abundant changes in the degron sequence. The promoter regions of multiple members of the JAZ gene family in P. tabuliformis contained cis-acting elements that respond to JA and GA, and had a close evolutionary distance from several JAZ proteins in model plants. Further experiments showed that the Jas domains of 5 JAZ proteins (TIFY 4, TIFY11, TIFY16, TIFY25, and TIFY59) in P. tabuliformis were interacted with PtDPL (DELLA-like), and identified the functional motif of JAZ-DELLA was Jas motif in P. tabuliformis.   Conclusion  This study clarified the basic sequence characteristics of JAZ gene family and identified the functional motif of JAZ and DELLA interaction in P. tabuliformis. At the same time, it also supplemented an important basis for the further study of JAZ gene family and JA-GA signaling pathway in conifers.
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Objective  By investigating the changes trend of street trees structure in Beijing from 2010 to 2020, the purpose of the research is to identify the main challenges and give references for street trees establishment and management in the future.   Method  Typical sampling methods and the same plots were used to investigate every street tree within Sixth ring road in Beijing from June to September in 2010 and 2020. The variation of ten years in street tree species composition, utilization frequency, crown diameter and species important value in Beijing were analyzed from different perspectives.   Result  Six families, ten genera and eight species have been increased during the last ten years in Beijing, and all of them were occasional species. The proportion of arbor and shrub has also increased. The street trees are mainly native species and deciduous species, with a higher proportion of deciduous species. The total proportion of top ten street tree species ranking by utilization frequency has increased, and proportion of Fraxinus chinensis trees was the highest one, while the decrease in utilization frequency of Rosa xanthina was the highest one in recent decade. The important value of Sophora japonica was still much higher than other street tree species though it was decreased by 8.2%. The average crown diameter of street trees decreased by 0.1m for massiveness of new planted trees. The proportion of street trees in the 1st and 5th crown diameter class has decreased. The top ten street tree species ranking by average crown diameter range has narrowed, and the Platanus acerifolia has been the most decreased species in the 1st crown diameter class.   Conclusion  The decreasing tree species diversity, and relatively sample tree species composition and higher proportion of single species are the main problems while could affect the stability of urban road vegetation ecosystem in Beijing. Therefore, the range of tree species selection should be broaden, mixed configuration with more broad-leaved deciduous tree species, evergreen shrubs and herbs should be constructed. The cultivation and application of native species should be strengthened, while the high-value exotic tree species should be introduced appropriately. At the same time, we should also protect the tree crown structure to enhance the shading effect of street trees in the urban greening.
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2022, 44(11): 1-2.
[Abstract](8) [FullText HTML](4) [PDF 308KB](1)
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2022, 44(11): 1-9.   doi: 10.12171/j.1000-1522.20210083
[Abstract](185) [FullText HTML](41) [PDF 2054KB](48)
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Objective  The development of secondary cell wall is vital for the wood formation, and revealing the molecular regulation mechanism of secondary wall formation in forest will provide a theoretical basis for improving its wood quality.  Method  (1) In this study, PdKNAT7 gene was cloned from fast-growing poplar NE19, and its expression vector was constructed. Arabidopsis thaliana was transformed by inflorescence infection, and overexpression plants were screened. (2) The subcellular localization of PdKNAT7 was implemented by Agrobacterium mediated transient transformation in tobacco. (3) The secondary thickening of flower stalk base in different genotypes of Arabidopsis thaliana was observed by hand sectioning. (4) 84K poplar was transiently transformed by vacuum infiltration. (5) qRT-PCR was used to analyze the expression of PdKNAT7 gene in different poplar strains, and reveal the expression patterns of related genes involved in secondary wall formation in Arabidopsis thaliana and poplar.  Result  (1) PdKNAT7 was localized in the nucleus. (2) PdKNAT7 was mainly expressed in the stem of NE19, and the expression level was higher than that of poplar 107. (3) Compared with the wild type, the interfascicular fiber wall of the flower stalk base of the overexpression plant became thinner, and the xylary fiber wall became thicker, while the mutant was just opposite to the overexpression plant; in addition, the vessel wall of mutant was thicker. (4) The expression levels of 4CL1, C4H1, CCR1, CesA8, IRX9 and IRX10 genes were down regulated in the overexpression plants, and the mutant was on the contrary. (5) The expression levels of 4CL3, C4H1, CCR1, CesA8, IRX9 and IRX10 genes in 84K poplar transiently transformed with PdKNAT7 gene were also down regulated.  Conclusion  PdKNAT7 affects the thickness of secondary cell wall by regulating the accumulation of lignin and cellulose in Arabidopsis thaliana.
2022, 44(11): 10-19.   doi: 10.12171/j.1000-1522.20210272
[Abstract](58) [FullText HTML](11) [PDF 3954KB](17)
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Objective  Recent studies have found that Hsp90 gene family is related to embryo development, but the details of Hsp90 gene family in chestnut are not clear. The identification and analysis of Hsp90 gene family in chestnut provide a theoretical basis for studying the function of Hsp90 gene family and its role in pollination, fertilization and ovule development, so as to improve the yield of chestnut.  Method  The members of chestnut Hsp90 gene family were identified by bioinformatics. The physical and chemical properties, gene structure, evolutionary relationship and promoter elements of the family members were analyzed. The expression of CmHsp90 genes at different developmental stages of ovule was analyzed based on transcriptome data.  Result  A total of 10 CmHsp90 genes were identified in Chinese chestnut. The length of CDS of 10 CmHsp90 gene family members ranged from 2 112 to 2 481 bp, the number of amino acids encoded ranged from 703 to 826. The relative molecular weight ranged from 80.67 to 94.21 kDa, and the pI ranged from 4.81 to 5.26 kDa. The coefficient of instability ranged from 36.15 to 46.75. Except CmHsp90-6, CmHsp90-4 and CmHsp90-9, the proteins encoded by other genes were relatively stable. According to the subcellular localization prediction of CmHsp90 family protein members, five members (CmHsp90-1, CmHsp90-4, CmHsp90-5, CmHsp90-9 and CmHsp90-10) were located in the cytoplasm, two members (CmHsp90-7 and CmHsp90-8) were located in the endoplasmic reticulum, and the other three members were located in the nucleus (CmHsp90-3), mitochondria (CmHsp90-2) and chloroplast (CmHsp90-6). By predicting the signal peptide of CmHsp90 gene family proteins, it was found that only CmHsp90-7 and CmHsp90-8 had potential signal peptide sites. The motif and protein domains of CmHsp90 gene family proteins were basically the same, including Hsp90 domain (PF00183) and HATPase_c domain (PF02518). Based on phylogenetic tree analysis, 10 CmHsp90 proteins were divided into 5 groups. The cis acting elements in the promoter region of CmHsp90 gene family were predicted. It was found that the light response element was the main regulatory element on the promoter of CmHsp90 gene family, followed by ABA response element. In addition, four genes (CmHsp90-1, CmHsp90-5, CmHsp90-7, CmHsp90-8) had temperature response elements. By analyzing the RNA-seq data of ovules at different developmental stages, it was found that the expression of other genes in ovules before fertilization was higher than that after fertilization, except CmHsp90-3 gene; the expression of CmHsp90-2, CmHsp90-4, CmHsp90-5, CmHsp90-7, CmHsp90-8, CmHsp90-9 and CmHsp90-10 genes in developing ovules was higher than that in abortive ovules.  Conclusion  The CmHsp90 genes in chestnut were identified and analyzed for the first time. The results show that the expression of Hsp90 genes is different in varied ovule development processes, and the expression in developing ovules and abortive ovules in the same ovary is also different. The research results lay a foundation for the further study of the specific role of CmHsp90 gene in chestnut pollination, fertilization and embryo abortion.
2022, 44(11): 20-30.   doi: 10.12171/j.1000-1522.20210289
[Abstract](83) [FullText HTML](19) [PDF 787KB](26)
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Objective  This paper aims to screen the key climate factors affecting the quality of chestnut, to evaluate the climate adaptability of chestnut in different ecological regions and its suitable planting regionalization, and also to provide theoretical basis for the introduction and scientific planting of chestnut.  Method  105 Chinese chestnut varieties (including superior lines) from 4 ecological regions in China (the Huanghuaihai, the Northwest, the middle and lower reaches of the Yangtze River, and the Southwest) were taken as the research objects. The differences of phenotypic traits such as single nut mass, fruit shape index, and the internal qualities such as soluble sugar, starch, and protein were analyzed. 12 climate factors from 24 main Chinese chestnut planting areas in the 4 regions were selected for principal component analysis to screen the climate factors that are most closely related to the formation of Chinese chestnut quality. The climate quality evaluation model of Chinese chestnut was constructed by stepwise regression. Climate adaptability index (CAI) was used to evaluate the climate adaptability of Chinese chestnut.  Result  (1) There were significant differences in phenotypic traits and intrinsic qualities of chestnut in different ecological regions. The single grain mass and fruit shape index in the middle and lower reaches of the Yangtze River were significantly higher than those in other regions. The soluble sugar and amylopectin/amylose ratio were the highest in the Huanghuaihai region. (2) The main climate factors affecting the quality of chestnut nuts were heat factor, followed by light factor and water factor. There was a significantly positive correlation between single grain mass and annual mean temperature and growing season precipitation, a significantly negative correlation between single grain mass and temperature difference, and a significantly negative correlation between fruit shape index and temperature. There were significant positive correlations between water content and annual precipitation, average temperature in growing season and precipitation in growing season. Soluble sugar had significantly positive correlation with annual sunshine duration, temperature difference in growing season and sunshine duration in growing season. Amylopectin/amylose ratio was significantly positively correlated with sunshine duration, average temperature, temperature difference and sunshine duration in growing season. Protein was positively correlated with annual mean temperature, and negatively correlated with annual sunshine hours and growing season sunshine hours. (3) According to CAI, 24 main planting areas of Chinese chestnut in the four regions can be divided into the most suitable area, the more suitable area and the suitable area. The CAI value of the northern Huanghuaihai area reached 0.90−0.96, which was the most suitable area; the CAI value of the east, northwest and southwest of the Huanghuaihai area was 0.81−0.89, which was a suitable area; the middle and lower reaches of the Yangtze River had the lowest CAI value, 0.71−0.77, which was suitable for the region.   Conclusion  The climatic conditions of large temperature difference, high average temperature, long sunshine hours in the growing season are favorable for the formation of sweet and waxy quality of chestnut nuts.
2022, 44(11): 31-40.   doi: 10.12171/j.1000-1522.20210212
[Abstract](84) [FullText HTML](12) [PDF 742KB](35)
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Objective  As the main organ for nutrient and water absorption, fine roots are the most active part of the plant root system and particularly sensitive to soil environment. Nitrogen (N) deposition changes the soil environment, and would certainly affect the structure and function of fine roots. Pinus koraiensis (PK) is an important species in broadleaved Korean pine forest. It is important to discuss the effects of different levels of N addition on the stoichiometry, morphological traits and anatomical structure of PK fine roots, understanding the variation and trade-offs of fine root traits under long-term N addition, and predicting the physiological function changes of plant roots under global climate change.  Method  Three sample plots were established in primary mixed coniferous forests in the Xiaoxing’an Mountains of northeastern China, four treatments were set up in July 2011, which were the control (CK, 0 g/(m2·year)), low nitrogen treatment (LN, 2.5 g/(m2·year)), medium nitrogen treatment (MN, 5.0 g/(m2·year)) and high nitrogen treatment (HN, 7.5 g/(m2·year)). Fine roots of PK were dug out in July 2019, and 1st−5th fine roots under N addition were determined, including fine root stoichiometry, fine root diameter, root length, root surface area, cortex thickness, cortical cell traits, stele diameter, ratio of stele to root diameter and tracheid traits.   Result  Compared with CK treatment, N addition significantly increased the TN content of PK fine roots, LN and MN treatments significantly reduced C∶N; LN and MN treatments significantly increased the diameter of 1st−5th fine roots and the mean length and surface area of 1st fine roots, but reduced the mean length and surface area of 2nd−3rd fine roots. LN treatment significantly increased the 1st−5th fine root stele diameter, and 1st−3rd fine root cortex thickness and cortical cell traits, and 4th−5th fine root tracheid traits.   Conclusion  Long-term N addition significantly changes the stoichiometry, morphological traits and anatomical structure of fine roots. The variation of fine root diameter is mainly derived from cortical thickness and stele diameter, the variation of cortical thickness is mainly derived from cortical cell diameter, and the variation of stele diameter is derived from mean tracheid diameter and total tracheid area, and fine roots respond to environmental changes by adjusting their morphology and anatomical structure to optimize their physiological functions.
2022, 44(11): 41-49.   doi: 10.12171/j.1000-1522.20210371
[Abstract](112) [FullText HTML](23) [PDF 799KB](38)
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Objective  In the cultivation process of energy forest, the cultivation pattern of short rotation coppice (SRC) has attracted attention from various countries due to its excellent performance in productivity and environment. However, the influence of different planting densities and management modes on its growth and productivity still needs further discussion. The purpose of this study was to investigate the difference in growth, productivity, and sustainability of two poplar clones’ short rotation coppice without later artificial water and fertilizer management.   Method  (P. tomentosa × P. bolleana) × P. tomentosa (hereinafter referred to as “B301”) and Populus × euramericana cv.‘74/76’ (hereinafter referred to as “107”) planted in Gaotang County, Shandong Province of eastern China were used as experimental materials, with three planting densities (5 000, 10 000, 20 000 plant/ha) and three different rotation cycles (2, 3, 4 years). It took 6 years to study the survival rate, shoot diameter (D22) at 22 cm aboveground, number of shoots per plant, and biomass per unit area during each cycle and during 6 years.   Result  (1) The survival rate of the two species was higher in two-year rotation cycle, and lower in the planting density of 20 000 plant/ha. The maximum value of survival rate was 98.89%, which appeared in the second round of B301 of 2-year rotation and the planting density of 10 000 plant/ha. After six years of short-rotation management, the survival rate decreased significantly in all treatments of two- and three- year rotation cycle, with the survival rate of B301 remained above 66%, and that of 107 above 58%. (2) Both the average D22 and the average stoop per stump of the two clones were larger in the lower planting density. The average D22 was larger in the longer rotation and the first rotation, while the average stoop per stump was larger in the 2- and 3-year rotation and the last two rotations. The largest average D22 of the two clones appeared in the first rotation of the four-year rotation and the planting density of 5 000 plant/ha. It could reach 5.83 cm in B301, while it could reach 7.32 cm in 107. The average stoop per stump of B301 ranged from 1.10 to 5.52, and that of 107 ranged from 1.14 to 9.55, and 107 has better resprout capacity. (3) Productivity of short-rotation coppice planted under this experimental conditions in North China: in a single rotation cycle, the average annual biomass per unit area was 3.36−13.42 t/(ha·year) for B301 and 4.58−14.45 t/(ha·year) for 107. During 6 years, the average annual biomass per unit area of B301 ranged from 5.10 to 9.95 t/(ha·year), while that of 107 ranged from 6.22 to 10.69 t/(ha·year). The total biomass per unit area was 30.63 − 59.68 t/ha for B301 and 37.32 − 64.17 t/ha for 107.   Conclusion  (1) Without artificial water and fertilizer management, the productivity of 2 species of short-rotation poplar coppice is the highest at the first rotation, and declines with the increase of the number of rotations. (2) To build SRC in this region, 107 is superior to B301 on the whole in order to obtain higher productivity. (3) Considering the actual planting and management costs in operation, the rotation period of 3 years and the plant density of 10 000 plant/ha are the more suitable rotation and planting density for these two poplar clones.
2022, 44(11): 50-59.   doi: 10.12171/j.1000-1522.20210201
[Abstract](105) [FullText HTML](17) [PDF 3819KB](40)
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Objective  Forest is known as the “lung of the earth”, which is the material and spiritual basis for promoting ecosystem circulation and human survival. Populus spp. is the broadleaved tree species with the largest cultivated quantity in China. Its characteristics of fast growth, easy reproduction, strong adaptability, and short rotation period are important for keeping the balance of wood supply and demand, promoting carbon sequestration, and realizing carbon cycle. Exploring the environmental impact mechanism on its growth is of great significance to realize the efficient management of forest resources and promote the construction of ecological civilization.   Method  In this study, a multiple regression model of Populus spp. DBH growth rate without considering or having considered environmental factors was established based on the continuous inventory data of Populus spp. in forest resources in China. Random forest (RF), gradient boosting machine algorithm (GBM) and support vector machine (SVM) were established. The optimal parameters of these algorithms were determined by the minimum RMSE. These models were evaluated by the mean absolute error (MAE), root mean square error (RMSE) and coefficient of determination (R2). The level of importance of meteorological climate, terrain, stand structure and other environmental factors on the growth of Populus spp. was explored.   Result  The DBH growth rate of Populus spp. was mainly affected by its own DBH, decreasing with the increase of DBH, and showing an obvious inverse “J” shaped trend. The model considering environmental factors had higher accuracy than that without considering. Especially, for the growth rate model of Populus spp., the R2 was increased from 0.066 to 0.403. The prediction effect of the machine learning algorithm was obviously better than the regression model algorithm. Among them, the accuracy of RF algorithm was the highest, with R2 reaching 0.730. The prediction result was basically the same as the actual value. The multivariate regression model, RF and GBM were basically consistent in explaining the importance of the model, while SVM had slight differences.  Conclusion  Although the accuracy of the regression model is slightly lower than that of the machine learning algorithm, it is a white box, which can provide a basis for determining whether the DBH is abnormal in the future inventory work. The growth of Populus spp. is affected by the growth environment and closely related to the geographical location. The low altitude areas with suitable temperature and abundant precipitation and the north slope areas with gentle slope and low slope position will be more suitable for its growth. The higher the density is, the less the conducive to its growth is. In the process of Populus spp. planting, the factors of afforestation location, weather and climate should be considered first. Secondly, the rationality of stand structure, especially stand density should be considered. Finally, we should consider whether the topographic structure is suitable for afforestation projects.
2022, 44(11): 60-69.   doi: 10.12171/j.1000-1522.20210261
[Abstract](68) [FullText HTML](10) [PDF 4317KB](16)
Abstract:
Objective  In order to know the dynamic changes of forest resources, detect the infringement of forest land promptly, quickly and accurately, and solve the application bottlenecks of mainstream remote sensing change detection methods such as high requirements of consistency for data source and data time, too much manual interventions and complicated process, this research used a multi-scale object-level segmentation and change extraction method based on high spatial resolution time-series images to merge and simplify the two processes of classification and detection in mainstream methods.  Method  Taking Baishui County in Shaanxi Province of northwestern China as the research area, using GF-1 and ZY-3 satellite data sources, the two remote sensing image bands were split and reorganized to form the time-series image, and the time-series image was segmented in a multi-scale object-oriented manner. The spectral change value of the segmentation result was statistically sampled to determine the critical point and establish the extraction threshold, and then the NDVI change value was used to optimize the result.   Result  Taking the results of manual visual interpretation as a reference, the detection accuracy of this method was 86.2%. Among the classes that successfully detected invading forests, classes with good or almost consistent shapes accounted for 48.8%.   Conclusion  This method can realize the rapid detection of invaded forest classes, and can meet the practical application needs of large-scale, multi-temporal, and mixed image data source forest resource monitoring in terms of detection efficiency, accuracy and adaptability.
2022, 44(11): 70-81.   doi: 10.12171/j.1000-1522.20220029
[Abstract](72) [FullText HTML](12) [PDF 7044KB](24)
Abstract:
Objective  The objective of this study was to explore the feasibility of GF-1, GF-3, and combination of GF-1 and GF-3 for total forest aboveground biomass (AGB) and its component inversion.  Method  In this study, the vegetation indices, texture characterizations extracted from GF-1, backscattering coefficients, texture characterizations and polarimetric decomposition features extracted from GF-3 were used independently and in combination to estimate total AGB and component AGB of a pure forest of Yunnan pine (Pinus yunnanensis), located in Xiaoshao Forest Region in Yiliang County, Yunnan Province of southwestern China. A fast iterative features selection method for k-NN method (KNN-FIFS) was applied in forest total AGB and component AGB inversion and the leave one out cross validation (LOOCV) method was used to evaluate the model and the inversion results and the results were mapped and analyzed.   Result  The joint GF-1 and GF-3 data had the highest accuracy for inversion of forest AGB and each component AGB, and the R2 of each exceeded 0.710, and the values of RMSEr were between 22% and 27%, among which the inversion accuracy of foliage was the best, with the model’s R2 of 0.714, RMSE of 10.270 t/ha, and RMSEr of 24.58%; except for foliage component AGB, forest AGB and other components of AGB had better accuracy than the inversion results with GF-3 features when only the features extracted from GF-1 were used for the inversion.   Conclusion  Combining GF-1 optical data and GF-3 fully polarized SAR data can achieve a certain degree of complementarity to improve the inversion accuracy of forest AGB and fractional AGB. In addition, the KNN-FIFS method is robust in the inversion of AGB and fractional AGB of pure Yunnan pine forests at low biomass levels, and the important parameters preferred by KNN-FIFS mostly are texture features extracted form SAR and optics data.
2022, 44(11): 82-89.   doi: 10.12171/j.1000-1522.20210249
[Abstract](58) [FullText HTML](13) [PDF 844KB](21)
Abstract:
Objective  To illuminate the effects of allelogenicity of Fraxinus mandshurica on defense proteins of larch in mixed forest, the activities of defensive proteins in larch conifers of banding mixed forest types with Fraxinus mandshurica were analyzed.  Method  Taking Larix olgensis as the control, that planted in pots and in the ground was mixed with Manchurian ash in 1∶1, 3∶3 and 5∶5 (HJ1∶1, HJ3∶3, HJ5∶5) bands, respectively. One year later, the activity of defense proteins in the needles of Larix olgensis was measured by ultraviolet spectrophotometer.  Result  The activities of defense proteins in needles of three kinds of banded mixed Larix olgensis planted in the field and pot were higher than those in the control. The activities of phenylalanine ammonia lyase (PAL), chymotrypsin inhibitor (CI), trypsin inhibitor (TI) and polyphenol oxidase (PPO) in HJ3∶3 needles were always higher than those in the control (P<0.05). Except August 1, the PPO activity in the needles of HJ3∶3 planted in the field was significantly higher than that in control (P<0.05), and there was no significant difference between HJ3∶3 and HJ5∶5 (P>0.05). The activity of defense protein in potted HJ3∶3 needles was always higher than that in the control (P<0.05), and HJ3∶3 was significantly higher than HJ1∶1 or HJ5∶5. Compared with pot culture, field planting HJ5∶5 was more beneficial to increase PAL activity in needles. However, the effects of HJ1∶1 on PPO activity in needles and HJ5∶5 on CI activity in needles were relatively small.  Conclusion  The zonal mixing with Fraxinus mandshurica can improve the activity of defense protein in the needles of Larix olgensis, and the HJ3∶3 mixing mode has the most significant effect, and its defensive protein activity is significantly enhanced.
2022, 44(11): 90-99.   doi: 10.12171/j.1000-1522.20210345
[Abstract](55) [FullText HTML](15) [PDF 1543KB](17)
Abstract:
Objective  Hylurgus ligniperda is an important quarantine pest of pine species, which has caused severe damages on pines in Chile, New Zealand and many other countries. The pest was recently confirmed to have invaded and established populations in Shandong Province of eastern China through imported wood materials, posing threats to the forestry security of China. Thus, accurate prediction of the climate-suitable regions of H. ligniperda is urgent for relevant institutions to take efficient quarantine and control measures, thus reducing the potential ecological and economic losses.   Method  Our research used Maxent model to predict the climate-suitable regions of H. ligniperda both at the global scale and in China, following the steps of bioclimatic variable selecting and model parameter optimizing. ArcGIS software was used to visualize the predictive results and make area statistics. The model results were used to analyze the contributing bioclimatic variables affecting the colonization of the pest.   Result  Compared with the Maxent model with the default parameters, the accuracy of the model with optimized parameters was significantly improved, with the average AUC value of 0.964 6. Meanwhile, the predictive results showed that the climate-suitable regions were mainly distributed in Europe, the east and west coasts of North America, the east of Asia, the southeast of South America, the southernmost tip of Africa and the southeast coast of Oceania, with the very suitable regions, suitable regions and marginal regions accounting for 1.21%, 1.92% and 3.95%, respectively. Within China, the climate-suitable regions of the pest were mainly located in the middle and south zones, which was bounded to Taiwan Province in the South and Dalian of Liaoning Province in the north. The areas of very suitable regions, suitable regions and marginal regions accounted for 0.28%, 5.00% and 13.43%, respectively. The bioclimatic variables having the most significant contribution are the precipitation of the driest quarter (37.9%), the minimum temperature of the coldest month (25.4%), the temperature seasonality (12.7%), the maximum temperature of the warmest month (7%) and the annual precipitation (6.6%).   Conclusion  Except for the areas where H. ligniperda already existed, the pest has not occurred in the climate-suitable regions in the southeast and northwest of the United States, the east of Argentina, the southern Brazil and most of China, indicating the high risk of H. ligniperda invasion in these regions. The climate-suitable areas of H. ligniperda in China are mainly represented by suitable regions and marginal regions, including almost all provinces in central and southern China, among them the coastal areas and surrounding regions of Shandong Province and Jiangsu Province, Western China, central and southern China have relatively higher suitability. Therefore, it is suggested that the survey and prevention measures should be implemented to control the spread of H. ligniperda, while the quarantine and control on wooden material should be strengthened at entry ports.
2022, 44(11): 100-110.   doi: 10.12171/j.1000-1522.20220054
[Abstract](85) [FullText HTML](11) [PDF 2277KB](21)
Abstract:
Objective  Bees, the main species of urban pollinators, have significant ecological service function. However, human activities and urbanization had led to a decline in the number and diversity of pollinators. Based on the bees vision model, we assessed the influence of floral color characteristics on the bees-attracted ability. The results could be useful for establishing a selecting indicator system for bees-friendly landscape plants and lay a foundation for maintaining the stability of urban ecosystem.   Method  Taking the commonly used landscape plants in six green spaces of Beijing as the research objects, we used the floral reflectance spectrum measured by a spectrometer and bees vision model to analyze the floral characteristics, including color diversity and contrast against the background of flowering plants in spring and summer-autumn.   Result  There were significant differences in the floral characteristics of flowering plants of different seasons and color systems. The mean absolute deviation and minimum absolute deviation (400 nm) of spring blooming plants were significantly lower than those of summer-autumn blooming plants, indicating that the spring blooming plants were easier to be perceived, while the floral color diversity of the spring blooming plants was lower. Moreover, comparing the flower color characteristics of white, yellow, red, pink, and blue-purple flower plants, we observed that the floral color diversity was high for yellow flower plants and low for the red ones. The values of mean absolute deviation and minimum absolute deviation indicated that yellow, white and pink flower plants were easy to be perceived, whereas it was hard for bees to perceive red flower plants.   Conclusion  The deviation value of floral color spectral marker-points, achromatic contrast against background and chromatic contrast against background could be used as indicators for selecting bees-friendly landscape plants.
2022, 44(11): 111-121.   doi: 10.12171/j.1000-1522.20210553
[Abstract](70) [FullText HTML](16) [PDF 16681KB](14)
Abstract:
Objective  Improving the quality of rural landscape is the key point to promoting the harmony between man and nature and forming a good living environment. Facing the needs of China’s rural residential environment construction in the new era, it is urgent for rural landscape to highlight regional characteristics through planning and design. This study explored the methods of landscape character assessment used in multi-scale rural space, in order to provide new ideas for the construction of regional rural landscape.  Method  This paper puts forward the practical application of landscape character assessment tool in rural landscape identification and construction. Taking Horqin Right Front Banner of Inner Mongolia, northern China as an example, firstly, the working framework of multi-scale rural landscape character assessment was constructed based on the traditional LCA tools. Secondly, the geographic information analysis platform was used to classify, identify and describe the rural landscape characters from multi-scale. Finally, the decision-making evaluation system of rural landscape was constructed, and the corresponding landscape development strategies were put forward.   Result  The landscape character map of the study area was obtained through analysis, and the optimization was put forward according to the analysis results, and the multi-scale and multi-level collaborative practice of rural landscape classification and decision-making from national scale to site level, from landscape characteristic area to landscape elements were completed.  Conclusion  Compared with the traditional rural landscape quality evaluation, the multi-type and multi-scale landscape characteristic assessment has obvious advantages in the identification and differentiation of regional rural landscape, which could match the national territory spatial planning and emphasize the attention to the characteristics and diversity combination of rural landscape, and provide a new idea and path for the sustainable development of rural landscape.
2022, 44(11): 122-131.   doi: 10.12171/j.1000-1522.20220229
[Abstract](66) [FullText HTML](24) [PDF 5672KB](13)
Abstract:
Objective  This paper aims to prepare a new nano SiO2-IPBC microcapsule fungicide and study its characteristics, as well as improve the fixation and aging resistance of 3-iodo-2-propynyl-butyl-carbamate (IPBC) in wood, and expand its application in the field of wood mildew proof.   Method  Nano SiO2-IPBC microcapsules were prepared by blending IPBC and nano SiO2 particles in a vacuum, nano SiO2 prepared by sol-gel method was the capsule wall, and IPBC was the capsule core. The microcapsules were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), UV-aging resistance, and slow-release performance. Taking Hevea brasiliensis as the research object, Botryodiplodia theobromae, Aspergillus niger, Trichoderma viride, and Penicillium citrinum as the tested strains. The comprehensive indicators were obtained from different mass fraction microcapsule-ethanol impregnated rubber wood treatments.  Result  Nano SiO2-IPBC microcapsules were regular spherical, with particle size distribution between 20–100 nm and coating rate of 46.33%. The temperature of the weight loss of microcapsules was 120–280 ℃. Only slight yellowing occurred after 60-min UV aging; in 20% ethanol aqueous solution, the release rate of microcapsules was fast in the first 60 min, gradually slowed down in the next 180 min, and its release rate reached 50% in 240 min. FTIR analysis showed that there were Si−OH bonds in the microcapsules. SEM showed that microcapsules were not only distributed in wood vessels, but also deposited in wood pits. The results of mildew proof experiment showed that with the increase of the mass fraction of the microcapsule fungicide, the control effect against 4 fungi had gradually improved. When the mass fraction of microcapsule fungicide increased to 1.25%, the control effect against Botryodiplodia theobromae, Aspergillus niger, Trichoderma viride and Penicillium citrinum reached the highest level, which were 78.125%, 75.000%, 68.750% and 62.750%, respectively. The order of control effect (from strong to weak) was as follows: Botryodiplodia theobromae > Penicillium citrinum > Trichoderma viride > Aspergillus niger.   Conclusion  The nano SiO2-IPBC microcapsules prepared in this study improve the UV aging resistance of IPBC, as well as has a slow-release effect. The microcapsule fungicide has an excellent inhibitory effect on the 4 common mildews of rubber wood and has the best control effect on Botryodiplodia theobromae.
2022, 44(11): 132-139.   doi: 10.12171/j.1000-1522.20220143
[Abstract](65) [FullText HTML](15) [PDF 771KB](13)
Abstract:
Objective  The Eucalyptus obliqua wood from Australia has extremely low permeability and is extremely prone to crack and shrink in the conventional drying process, and it is difficult to ensure the quality. In this study, the intermittent treatment was introduced into the conventional kiln drying process, and an intermittent conventional drying schedule was established, which shortened the drying time of E. obliqua lumbers and improved the drying quality as well.  Method  The drying characteristics and possible drying defects were obtained by the 100 ℃-test method proposed by Tarazawa. Combined with Keylwerth’s chart method, the preliminary drying schedule for 30 mm thick E. obliqua lumbers was proposed. Intermittent treatments were applied based on the extent of collapse observed on the sample surface at the early stage of drying. The final drying quality of lumber samples was evaluated according to GB/T 6491−2012 “Drying Quality of Lumbers” from the aspect of moisture content gradient, degree of bending, checking and collapse.  Result  The average basic density of E. obliqua samples in this study was (558 ± 21) kg/m3. Based on the defect grades from the flatsawn and quartersawn 100 ℃-test samples, the final defect grade of E. obliqua wood was evaluated as “Grade-4” for the initial checking, “Grade-5” for the internal checking and “Grade-5” for the cross-section deformation. The initial temperature of the conventional drying schedule for 30 mm thick E. obliqua lumber was set at 46 ℃ with the wet-bulb depression of 1.5 ℃, and the final maximum temperature was set at 67 ℃. During the drying process, severe collapse was observed when the average moisture content of the specimens was 37.7%, 34.4% and 24.4%, and three batches of intermittent treatments were followed with the treatment time of 16, 8 and 8 h, respectively. The specimens were dried from an average initial moisture content of 61.0% to a final one of 10.8% in a total of 20 d, with an average drying rate of 0.10%/h. The moisture content deviation in the thickness direction of the specimen was 0.70%. Most drying defects such as spring, bow, twisting, surface and internal checks of the specimens met the first-class standard, but cupping and collapse of the specimen were more serious, only meeting Grade-3 standard.   Conclusion  The 100 ℃-test shows that the cross-section deformation caused by collapse is the most serious drying defect of E. obliqua woods, and the collapse extent of the quartersawn samples is greater than that of the flatsawn samples. Adding intermittent treatments to the preliminary conventional drying schedule based on the 100 ℃-test could effectively alleviate and prevent further collapse development effectively. A small amount of collapse still occurs on the 30 mm-thick E. obliqua specimens dried in this study, therefore not meeting the Grade-2 drying quality in GB/T 6491−2012, which is usually required by most enterprises in China. However, the drying time was reduced approximately 90% compared with that of the traditional combined air and conventional kiln drying method, and the drying quality was improved. The intermittent drying schedule recommended in this study can provide insights into the actual drying of E. obliqua woods in the industry.
2022, 44(11): 140-151.   doi: 10.12171/j.1000-1522.20220251
[Abstract](104) [FullText HTML](25) [PDF 7362KB](22)
Abstract:
Objective  With a history of about 870 years, the Jinzhongdu Watergate Site is the largest surviving site of the Jinzhongdu. The wooden structure, as the foundation and main body of the site, plays an important role in the whole watergate structure. The researchers explored the detailed composition of the wooden structure of the watergate site, conducted nondestructive inspection and assessed the defective condition of the wooden components, with the aim of providing a basis for the repair and conservation of the Jinzhongdu Watergate Site, as well as providing a reference for nondestructive inspection and assessment of underground wooden structures of the same type.  Method  Firstly, the researchers surveyed and calibrated the wooden structure site, and received the typical size, location, amount and interconnection information of the three types of wooden components, including stone fixed timber pile, foundation timber pile and stone lined square. The wooden structure model of the watergate was also restored. Secondly, according to the respective characteristics of the three types of wooden components, the researchers took 236 such woods as examples and conducted on-site testing and laboratory analysis, including knockdown, dimensional measurement, moisture content measurement, micro-drilling resistance testing and tree species identification. Finally, the information from the on-site inspection and laboratory analysis would be summarized, as well as the grades of the condition of the tested wooden components, and the laws of decay defects of wooden components.  Result  A three-dimensional model of the wooden structure of the Jinzhongdu Watergate Site was reconstructed, and it was concluded that its wooden structure was supposed to be composed of 204 stone fixed timber piles, 771 foundation timber piles and 92 stone lined squares. The main defects of the wooden components of the site were decay and the lack of material caused by decay, and the secondary one was cracked. In terms of single wood members, the decay of overground part was comparatively light, while the decay of the underground part was comparatively serious. The species of wood members at the site were mainly Larix principis-rupprechtii, mixed with Pinus sylvestris var. mongholica.   Conclusion  The overall condition of the wooden structure of the Jinzhongdu Watergate Site was destructive, and no A-class wooden components in good condition were found. Among the three types of wooden components, the overall condition of the stone fixed timber piles is relatively the best, while the overall condition of the foundation timber piles is relatively the worst. The practice has proved that it is feasible to detect and evaluate the defects of the wooden components of Shuiguan Site by comprehensively using percussion, size measurement, moisture content measurement and micro drilling resistance detection.

Establishment Time:1979

CN 11-1932/S

ISSN 1000-1522

Supervisor:Sinopec Research Institute of Petroleum Engineering