To investigate the genetic variation in growth rhythm of Dalbergia odorifera seedlings from different provenances, so as to provide a theoretical basis for superior provenance selection and efficient seedling cultivation.

One-year-old seedlings from nine provenances in Hainan were regularly measured for height and ground diameter. The annual growth process was fitted using the Logistic growth curve, and key growth parameters including maximum growth rate (MGR), rapid growth rate (RGR), growth increment during the rapid growth period (RIG), and the proportion of rapid growth period (PRT) were calculated. Correlation and cluster analyses were conducted in combination with geographical and climatic factors. The genetic parameters such as heritability were estimated by the ASReml-R 3.0.

The Logistic model showed a good fit for both height and ground diameter growth (R²>0.98), with seedling growth following a typical “S”-shaped curve, which could be divided into initial, rapid, and late growth phases. Significant differences were observed among provenances in both phenological and growth parameters. The rapid growth period of ground diameter occurred earlier than that of height, with average starting times of day 47 and day 117, respectively. MGR, RGR, and RIG were significantly positively correlated with annual precipitation of the provenances, indicating that moisture is an important environmental factor affecting growth rate. Cluster analysis grouped the nine provenances into two categories based on geographical structure. With the exception of PRT, significant differences in growth rhythm parameters were observed between groups. Genetic analysis revealed that heritability was generally higher for ground diameter than for height, and growth rhythm traits exhibited moderate heritability with low coefficients of genetic variation, indicating that these traits are mainly under genetic control and have high potential for genetic improvement.

The growth rhythm of D. odorifera seedlings exhibits clear differences among provenances and geographic variations. Annual precipitation is an important environmental factor influencing growth rate. The Logistic model can accurately predict growth processes, providing a reliable basis for scientific seedling cultivation, provenance selection and genetic improvement, the results of this study offer important theoretical and technical support for superior breeding and efficient cultivation of D. odorifera.

This study aims to investigate the long-term and effective protection mechanisms for ecological protection redline areas, which are crucial for maintaining ecological security patterns, ensuring ecosystem functionality, and supporting sustainable socioeconomic development.

The research took the ecological protection redline areas in the Poyang lake basin as its study object. It constructed a dynamic ecological quality monitoring system based on the "matrix-stress-wildness" framework by integrating multi-source remote sensing data and ground monitoring data. The study introduced the XGBoost machine learning algorithm to adaptively adjust weight thresholds and establish a modified ecological quality index. Furthermore, it employed Theil-Sen trend analysis, Mann-Kendall test, and long short-term memory (LSTM) neural network to systematically reveal and predict the spatiotemporal evolution patterns and future development trends of ecological quality within the ecological protection redline areas of the Poyang lake basin.

The ecological quality within the ecological protection redline areas of the Poyang lake basin showed distinct phased characteristics temporally. During the rapid change period, spatial heterogeneity of ecological quality significantly intensified, with widening disparities among different land use types. In the stable adjustment period, the overall fluctuation range of ecological quality tended to moderate, with restorative improvements observed in some areas, reflecting the positive effects of ecological protection policies. Spatially, regions with lower ecological quality are mainly concentrated in the northwestern mountainous and hilly areas, the central basins characterized by concentrated agriculture and urbanization, and the northern lake areas affected by significant human activities. In contrast, areas with higher ecological quality are primarily distributed in the southern part of the basin, which features high natural vegetation coverage and minimal human disturbance. LSTM model predictions indicated that future ecological quality is primarily classified as "poor" and "medium," with "good" quality areas covering only 10 600 km² and concentrated in the Ganjiang river source reserve. Typical ecologically vulnerable areas continue to face multiple anthropogenic and natural pressures.

The monitoring and assessment system established in this study effectively identifies the spatiotemporal evolution characteristics of ecological quality, providing data support and theoretical references for precise management and policy formulation in ecological protection redline areas.

Nutrient resorption from senescing tissues is recognized as a strategy for plants to adapt to nutrient deficiency. However, how nutrient resorption regulates the balance of nutrient elements within plants remains unclear, particularly under conditions of increased soil nitrogen availability.

This study investigated the changes in nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), and magnesium (Mg) content in green and senescent leaves, as well as soil nutrient contents, in a subtropical Castanopsis hystrix plantation under different N addition treatments (Control, CK: 0 kg·hm^-2·a^-1; Low N, LN: 50 kg·hm^-2·a^-1; Medium N, MN: 100 kg·hm^-2·a^-1; High N, HN: 150 kg·hm^-2·a^-1). The overall patterns and main drivers of nutrient resorption efficiency and its stoichiometric ratios were also examined.

The results showed that the HN treatment significantly increased soil dissolved inorganic N (DIN) content, leading to a significant decrease in soil DOC∶DIN and a significant increase in soil DIN∶AP (P<0.05), indicating that long-term high N input exacerbates soil P limitation. Under N addition, the concentrations of N, P, Ca, and Mg in both green and senescent leaves showed an increasing trend. MN and HN significantly increased green leaf total N (TN) content; MN significantly increased green leaf total P (TP) content; LN and HN significantly increased green leaf Ca content. LN, MN, and HN significantly increased senescent leaf TN content; HN significantly increased senescent leaf Ca content. LN, MN, and HN significantly decreased nitrogen resorption efficiency (NRE); phosphorus resorption efficiency (PRE) was significantly reduced only under the LN treatment. N addition had no significant effect on potassium, calcium, or magnesium resorption efficiency (KRE, CaRE, MgRE). Furthermore, senescent leaf nutrient content was significantly negatively correlated with resorption efficiency, indicating that nutrient resorption in C. hystrix is primarily regulated by senescent leaf nutrient status.

Our findings provide a theoretical basis for nutrient management in subtropical C. hystrix plantations and for understanding ecological adaptation strategies under nitrogen deposition.

To explore the effects of stand types on plant diversity and soil stoichiometric characteristics, and to provide theoretical references for afforestation and vegetation restoration and reconstruction in arid and semi-arid regions.

In this study, Pinus tabuliformis×Cotinus coggygria (Pt×Cc), Pinus tabuliformis×Quercus mongolica (Pt×Qm), Pinus tabuliformis×Caragana korshinskii (Pt×Ck), Pinus tabuliformis×Prunus sibirica (Pt×Ps), Pinus tabuliformis×Acer mono (Pt×Am) and Pinus tabuliformis (Pt) were selected as the research objects. Based on the investigation of typical plots and the results of indoor experiments, the understory diversity and contents, stocks and stoichiometric ratios of soil organic carbon (SOC), total nitrogen (TN) and total phosphorus (TP) in the soil were calculated.

Stand types significantly influence the composition and diversity characteristics of understory shrubs and herbs. The understory plant species are as follows: Pt×Qm (39 species), Pt×Ck (38 species), Pt×Cc (27 species), Pt×Ps (27 species), Pt (21 species), and Pt×Am (20 species). The dominant species in the shrub layer consist primarily of regenerating saplings from the mixed tree species, while the herb layer is co-dominated by Lespedeza bicolor and Carex lanceolata. In the shrub layer, the plant diversity index of the Pt×Qm was significantly higher than that of other stands. The plant richness of Pt is the lowest, but the evenness index is relatively high. In the herb layer, the Pt×Ck exhibited the highest plant diversity index, while the Pt showed a relatively high plant diversity index with no significant difference compared to most other forest stands. The content and stocks of SOC and TN in mixed forests were significantly higher than those in pure forests, and there was no significant difference in TP content and stocks. The soil C∶N of Pt×Qm and Pt×Cc showed no significant differences compared to Pt, while their soil C∶P and N∶P were significantly higher than that of Pt. The comprehensive scores of the six stand types were ranked as follows: Pt×Qm>Pt×Cc>Pt×Ck>Pt×Ps>Pt×Am>Pt.

Introducing broadleaf tree species into Pt can enhance understory plant diversity and promote soil nutrient retention. The Pt×Qm demonstrates optimal performance in terms of species diversity and soil nutrient content, making it an ideal configuration for ecological restoration efforts.

This study aimed to characterize the woody species composition and community structure of a typical southern subtropical evergreen broad-leaved forest in China, elucidate its succession pattern, species diversity, and development trend, and to provide a scientific basis for the refined management and biodiversity conservation of forest ecosystems in this region.

Sixteen permanent plots, each covering an area of 1 200 m², were established in a secondary forest in Conghua, Guangzhou, which had naturally regenerated after logging in the 1990s. All woody plants with a diameter at breast height (DBH)≥5 cm were surveyed within each plot. The species composition, species diversity, diameter-class structure, and vertical stratification of the community were systematically analyzed.

1) A total of 4 095 woody individuals (DBH≥5 cm) were recorded in the plots, belonging to 58 species, 46 genera and 34 families; and the families Lauraceae, Ebenaceae and Fagaceae were predominant; 2) Eight family and 11 genus distribution area types were identified, with tropical elements predominantly accounting for 64.71% of families and 65.22% of genera; 3) Twenty-three species had an importance value above 1%; the top six dominant tree species were Machilus chinensis, Diospyros morrisiana, Schima superba, Castanopsis faberi, Triadica cochinchinensis and Camphora parthenoxylon; and M. chinensis was absolutely dominant (importance value: 22.36%); 4) The diameter-class structure showed a typical reverse “J”-shaped distribution, indicating favorable community regeneration; 5) The vertical structure was stratified into four layers: sapling (2.5-9.3 m), sub-canopy (9.4-12.9 m), mid-canopy (13.0-16.5 m), and upper-canopy layers (16.6-25.8 m), trees in the sub- and mid-canopy layers together accounted for 64.96%, and species diversity decreased significantly with increasing canopy height; 6) The overall species diversity of the community was moderately high, but individual abundance was unevenly distributed among species, concentrated in a few dominant tree species.

This community represents a typical warm subtropical evergreen broad-leaved forest in the Pearl River Delta region. Currently in a mid-succession stage, it is characterized by generally small tree diameters, a stable structure, and a growing trend. Forest quality can be rapidly improved through target-tree management and enrichment planting with valuable tree species characteristic of middle and late succession stages.

This study aimed to explore the variation characteristics of net ecosystem productivity (NEP) and its environmental regulation in a typical artificial mixed coniferous and broad-leaved forest ecosystem in Beijing, clarify its carbon sequestration function, and to support the goals of carbon peaking and carbon neutrality.

An artificial mixed coniferous and broad-leaved forest ecosystem located in Beijing was selected as the study site. Continuous in-situ observations of NEP were conducted throughout 2023 using the eddy covariance (EC) technique. Simultaneously, environmental factors, including photosynthetically active radiation (PAR), vapor pressure deficit (VPD), air temperature (T_a), and soil water content (SWC), were monitored. The random forest model was used to calculate the importance scores of these environmental factors and to quantify their impacts on NEP and carbon sequestration.

The energy closure of the measurements was 0.72, The average daily and seasonal variations of NEP exhibited unimodal trends, with NEP peaking at 11.95 μmol·m^-2·s^-1 in July during the growing season (March–November). The ecosystem acted as a carbon sink during the growing season, with a net carbon sequestration of 384.83 g·m^-2, whereas it functioned as a carbon source in the non-growing season, releasing 1.18 g·m^-2. The total annual net carbon sequestration was 383.65 g·m^-2. Seasonal variations in NEP showed an initial increasing trend followed by a decrease, significantly influenced by PAR, SWC, VPD and T_a (P<0.01). Among these factors, PAR was the dominant environmental factor controlling NEP and carbon sequestration, with an importance score of 56.42 determined by the random forest model. The thresholds of environmental factors influencing NEP were 400 μmol·m^-2·s^-1 (PAR), 0.17 m³/m³ (SWC), 1.5 kPa (VPD), and 28 ℃ (T_a). Additionally, when SWC was below 0.1 m³/m³, it initially increased with rising T_a, but after exceeding 10 ℃, SWC decreased. The indirect regulatory threshold of T_a on NEP was thus identified as 10 ℃.

The studied artificial mixed coniferous and broad-leaved forest exhibited moderate carbon sequestration capacity. PAR was the primary factor controlling seasonal variations in carbon sequestration. The findings provide scientific support for managing carbon sink enhancement in artificial mixed coniferous and broad-leaved forest ecosystems in Beijing. Additionally, the observational dataset constitutes an important supplement for validating models used in forest carbon estimation.

To reveal the altitudinal distribution pattern and driving factors of soil fungal communities in Sabina przewalskii natural forests, thereby providing a theoretical basis and scientific support in the field of soil microbiology for the ecological protection of the Qilian mountains.

Focusing on the Sabina przewalskii natural forests soil at different altitudes in Qilian mountains, the high-throughput sequencing technology was used to analyze the diversity and community composition of soil fungi and explore the main factors influencing the soil fungal community structure.

A total of 6 phyla, 27 classes, 81 orders, 170 families, 295 genera and 355 species of soil fungi were discovered across different altitudes at the phylum level, Basidiomycota and Ascomycota dominated the fungal communities, with relative abundances of 0.22-0.66 and 0.11-0.39. Hygrocybe and Mortierella were the dominant genera. There were significant differences in soil fungal among different altitudes (P<0.05), with the richness and diversity of soil fungal communities at low and medium altitudes being significantly higher than those at high altitudes. Overall, the soil fungal diversity first increased and then decreased with increasing altitude. Redundancy analysis (RDA) and Spearman correlation analysis showed that altitude, soil pH, SOM, TP, AK and AP were the key environmental factors affecting the community structure and diversity distribution pattern of soil fungal.

The soil fungal community in Sabina przewalskii natural forests of the Qilian mountains is rich in composition, with Basidiomycota and Ascomycota as the dominant phyla. Soil pH, AP and TP are the core variables driving the soil fungal community structure. In addition, fungal diversity is negatively correlated with altitude and HN, while positively correlated with AK and SOM.

By cloning the BpbZIP36 gene, constructing a plant expression vector, and obtaining stable transgenic birch plants, this study aimed to investigate the drought resistance function of the BpbZIP36 gene.

Using birch as the experimental material, the BpbZIP36 gene was cloned from birch cDNA as the template. Bioinformatics analysis was performed on the gene, and the pROK2-BpbZIP36 plant expression vector was constructed and introduced into birch seedlings to obtain transgenic birch overexpressing BpbZIP36. The transgenic birch plants and wild-type were subjected to drought stress to study the drought resistance function of the BpbZIP36 gene.

A bZIP gene was obtained from the birch genome database, with an open reading frame (ORF) of 1 269 bp encoding 422 amino acids. The results of multiple sequence alignment showed that the BpbZIP36 protein was similar to the bZIP protein of other plants and a conserved bZIP structural domain. qRT-PCR results showed that the BpbZIP36 gene was expressed in roots, stems, and leaves. In stems and leaves, the expression level of BpbZIP36 peaked at 72 h, while in roots, the highest expression was observed at 24 h of stress treatment, indicating that the BpbZIP36 gene could be induced by drought stress. Physiological index and histochemical staining analyses revealed that under drought stress, the transgenic birch overexpressing BpbZIP36 exhibited lower MDA, H₂O₂ content, and relative electrical conductivity compared to wild-type plants, indicating better cell membrane integrity. The SOD, POD and CAT activities, as well as relative water content, were higher in the transgenic birch. DAB staining showed the lightest coloration in the three overexpression lines, suggesting lower H₂O₂ accumulation and reduced cellular damage. These results demonstrated that the drought resistance capacity of the transgenic birch overexpressing BpbZIP36 was stronger than that of wild-type.

Overexpression of the BpbZIP36 gene enhances the drought resistance capability of transgenic birch.

Ormosia microphylla is a rare and endangered tree species endemic to China and is listed as a Class I nationally protected wild plant. It possesses high economic and ecological value. Due to limited seed sources, traditional seed propagation methods have a low propagation coefficient; therefore, tissue culture technology has become an important approach for the rapid propagation of O. microphylla. This study aimed to establish an in vitro rapid propagation system for O. microphylla.

Mature seeds of O. microphylla were used to establish an aseptic seedling culture system, and the optimal seed sterilization protocol was screened. Bud-bearing stem segments from germinated aseptic seedlings were used as explants, and an L₉(3³) orthogonal experimental design was employed to determine the optimal medium for shoot induction and proliferation. The effects of different subculture cycles on proliferation were analyzed during the subculture stage. Finally, rooting and transplanting experiments were conducted to screen for the optimal rooting medium and the most suitable transplanting substrate.

The optimal sterilization protocol was to retain the seed coat and disinfect the seeds with 2% NaClO for 12 min, under which no contamination occurred, with an aseptic seedling rate of 70.37% and a browning rate of 23.23%. The optimal proliferation medium was MS supplemented with 1.5 mg·L^-1 6-BA and 0.15 mg·L^-1 IAA, yielding a proliferation coefficient of 5.23 and an average shoot height of 3.59 cm. The third subculture cycle showed the best proliferation performance, with a proliferation coefficient of 5.33. The optimal rooting medium was 1/2 MS supplemented with 0.3 mg·L^-1 NAA, resulting in a rooting rate of 93.33%, an average of 3.95 roots per shoot, and an average root length of 3.63 cm. The highest survival rate (95.56%) was achieved when vermiculite∶perlite (1∶1) was used as the substrate.

This study established a relatively stable and efficient in vitro rapid propagation system for O. microphylla. Based on experimental investigations of key procedures including explant sterilization, bud induction and proliferation, subculture, rooting and acclimatization, this work provides a theoretical basis and technical support for the germplasm conservation and large-scale propagation of this species.

To investigate the out-of-plane compressive performance of laminated bamboo grid sandwich panels under different loading conditions, and to provide both theoretical foundations and experimental support for their lightweight applications in modern green prefabricated buildings.

This study focused on flat-pressed laminated bamboo grid sandwich panels fabricated from Phyllostachys edulis sourced from Taojiang County, Hunan Province. Two core configurations were designed: axial parallel-to-grain and axial perpendicular-to-grain. A total of 18 specimens were prepared (3 parallel specimens for each of the 2 core types under 3 loading conditions). Out-of-plane compression tests were conducted under concentrated, linear, and planar loads to systematically investigate their failure mechanism and mechanical properties.

The laminated bamboo grid sandwich panels exhibited significantly distinct failure modes under different loading conditions. Under concentrated load, failure primarily manifested as localized face-sheet fracture; under linear load, face-sheet fracture dominated; while under planar load, the predominant failure modes were web buckling and fracture. Axial parallel-to-grain core specimens demonstrated superior mechanical performance across all three loading conditions compared to axial perpendicular-to-grain specimens, with compressive strength increasing by 33.3%, 130.3% and 178.0%, compressive modulus increasing by 36.4%, 16.6%, and 25.2%, and energy absorption capacity increasing by 14.3%, 72.5% and 186.6%, respectively. As shown in the results, the load-displacement curves exhibited typical nonlinear characteristics, with axial parallel-to-grain specimens showing higher stiffness but lower ductility, while axial perpendicular-to-grain specimens displayed the opposite behavior.

The failure modes of specimens showed significant differences under different loading conditions (concentrated load, linear load, planar load). Meanwhile, the core type significantly affected the out-of-plane compressive performance of specimens, specifically showing that axial parallel-to-grain core specimens exhibited notably higher compressive strength, compressive modulus and energy absorption capacity than axial perpendicular-to-grain core specimens.