We combined bioinformatics and synthetic biology to identify key gene families involved cannabidiol (CBD) synthesis and reconstituted the complete CBD pathway in Nicotiana benthamiana. Genome-wide analysis identified 128 genes in Cannabis sativa belonging to five families: CsAAE, CsTKS, CsOAC, CsPT and CsBBE. Phylogenetic analysis revealed the closest homology between C. sativa and Morus notabilis, with the key enzyme genes CsCBDAS, CsTHCAS, and CsCBCAS forming a conserved cluster within the BBE family, suggesting a common ancestral origin. Conserved motifs and gene structures analyses showed evolutionary strategies ranging from high conservation (CsOACs and CsBBEs) to diversification (CsTKSs). Promoter cis-element analysis indicated complex regulatory by light, hormones, and stress. Tissue-specific expression profiles confirmed high activity in flowers at specific developmental stages. The core genes were assembled into a multigene vector using a 2 A peptide system for transient expression in N. benthamiana. Molecular analyses verified successful integration and transcription of all genes. The final CBD concentration in the transgenic N. benthamiana reached 9 mu g/mg dry weight. This study provides the first demonstration of complete CBD pathway reconstitution in a plant chassis, offering new insights into cannabinoid pathway evolution and establishing a technical framework for plant-based cannabinoid production.

The succession of plant communities and soil-driven mechanisms triggered by wetland degradation are central issues in global ecology. To investigate the effects of Deyeuxia purpurea wetland degradation on plant community characteristics and its key soil regulatory factors, this study selected D. purpurea wetlands with different degradation degrees in the Sanjiang Plain as research objects and analyzed the characteristics of plant communities, soils, and their relationships. The results indicated that wetland degradation was significantly associated with turnover in plant community composition, with hydrophytic species progressively replaced by mesophytic and xerophytic species. As degradation intensified, Simpson's diversity index, the Shannon-Wiener index, Pielou's evenness index, and Patrick's richness index all increased significantly. The non-degraded wetland exhibited significantly higher aboveground, belowground, and total biomass than the degraded wetlands. Aboveground and total biomass showed a significant negative correlation with the diversity index. Soil pH, water content (WC), total phosphorus (TP), dissolved organic nitrogen (DON), and ammonium nitrogen (NH4+-N) were key factors associated with changes in plant community diversity and biomass. Partial least squares path modeling (PLS-PM) and variance partitioning analysis (VPA) further quantified potential association pathways, showing that wetland degradation exerted both direct and indirect effects on key soil physicochemical factors and plant community characteristics. Specifically, wetland degradation was directly associated with decreases in soil pH, WC, and TP, while positively affecting soil dissolved organic nitrogen (DON) and plant diversity. It also indirectly influenced plant species composition and biomass through changes in soil pH, WC, DON, and TP. TP was negatively correlated with plant diversity and biomass, whereas ammonium nitrogen had a direct positive effect on species composition. Dissolved organic nitrogen directly negatively affected species composition. Overall, this study systematically elucidates plant community response patterns and the synergistic driving mechanisms of multiple soil factors during D. purpurea wetland degradation, providing an important scientific basis for wetland conservation and ecological restoration in the Sanjiang Plain.

Climate warming and human activities have led to widespread expansion of shrubs in many wetlands, altering the distribution patterns of native vegetation and disrupting C cycling. Although the effects of shrub expansion on soil microbial communities and methane (CH4) emissions have been extensively studied, the specific microbial-mediated pathways involved in methane cycling remain unexplored. The static chamber method was used to investigate the characteristics of CH4 emission flux changes under different levels of shrub expansion. Additionally, metagenomics technology was employed to assess the effects of different shrub expansion levels on soil microbial community composition, function, and diversity (bacteria and fungi), as well as the methane metabolic pathways mediated by these communities. Shrub expansion in wetlands was categorized into four classes based on shrub coverage. We found that methane flux decreased significantly with increasing shrub expansion, with cumulative emissions under extensive expansion conditions being only 28 % of those under no expansion conditions. The peak emissions on August 15 under no expansion conditions were 2-3 times higher than those in shrub-expanded plots. The partial least squares path model (PLS-PM, GOF = 0.731) indicated that shrub expansion enhanced soil physicochemical properties (beta = 0.865), which inhibited methanogenic genes (beta = -0.617) and activated methane oxidation pathways (total effect beta = 0.728). Methane-oxidizing genes contributed the most to CH4 reduction, accounting for 72.4 % of the pathway effect. This was primarily manifested as inhibition of key genes involved in the acetate pathway for methane production (comB and hdrA) and upregulation of methane-oxidizing-related genes (mmoB and DAK). Shrub expansion significantly increased soil ammonium nitrogen content while reducing soil moisture content. Although bacterial alpha diversity remained unchanged, the fungal Chao1 index significantly increased. Additionally, MI and HI treatments significantly altered bacterial community structure, while fungal communities remained relatively stable. The relative abundance of Verrucomicrobia initially increased with shrub expansion but decreased at higher levels, while Ascomycota, Basidiomycota, and Mucoromycota showed significant increases. The study suggests that the reduction in CH4 emissions caused by shrub expansion is primarily regulated by a synergistic pathway involving the combined effects of soil physicochemical properties and oxidative microbial genes. Furthermore, bacterial communities are more sensitive to shrub expansion than fungal communities. These results highlight the complex interactions between aboveground vegetation dynamics, soil microbial communities, greenhouse gas fluxes, and environmental factors. However, this CH4 reduction likely reflects hydrological degradation and wetland desiccation, which may increase CO2 emissions from oxidized peat and compromise long-term carbon sequestration, underscoring the need to prevent shrub encroachment for wetland conservation.

Increasing atmospheric CO2 concentration can enhance plant photosynthesis and promote plant growth, thereby affecting the N cycle. To investigate the effects of long-term elevated atmospheric CO2 concentration (eCO2) and N deposition on N absorption and distribution in Calamagrostis angustifolia wetlands in the Sanjiang Plain, this study was conducted in open-top chambers (OTC-1) with 15 years of continuous elevated CO₂ concentration and simulated nitrogen deposition treatment.The focus was on exploring the impacts of climate change on N absorption, distribution, and N use efficiency (NUE) in Calamagrostis angustifolia. The results showed that under long-term CO2 fumigation, N concentration in various plant organs and the whole plant significantly decreased, with greater decreases observed in leaves at the heading stage, stems during the growth stage, and roots at the mature stage. Under eCO2 concentration and N fertilization treatments, NUE in Calamagrostis angustifolia stems gradually decreased with plant growth and development; NUE in leaves initially increased and then decreased; and the variation pattern of NUE in roots was not obvious. Total N accumulation remained unchanged, but a large amount of N was allocated to leaves, promoting N flow to the upper parts of the plant and enhancing the ability of leaves to acquire N. Moreover, high-N treatments alleviated the negative impact of long-term CO2 fumigation on biomass, especially during the growth stage, where leaf biomass increased by 87.0% and aboveground biomass increased by 35.2%. However, high-N treatments did not improve NUE in various Calamagrostis angustifolia organs. In addition, long-term CO2 fumigation led to a significant decrease in N content in leaves and roots, and the interaction between elevated CO2 concentration and N significantly affected the ability of roots to absorb exogenous N. Therefore, this study indicates that long-term CO2 concentration fumigation affects plant N absorption and utilization through N availability, providing theoretical support for selecting varieties with higher NUE in agricultural production.

This study identified 57 CsaMADS genes in Cannabis sativa L., characterized the expression and homology of key candidates CsaSOC1 and CsaFUL, and confirmed their protein interaction, thereby providing a molecular basis for investigating flowering regulation. MADS-box transcription factors are central regulators of plant growth and development, particularly in floral morphogenesis and the control of flowering time. In this study, we identified 57 MADS-box genes in hemp (Cannabis sativa L.) and classified them into Type I (22 genes) or Type II (35 genes) groups, which were further categorized into 15 distinct subfamilies. Genes within the same subfamily exhibited similar exon–intron structures and highly conserved protein motifs. Evolutionary analysis of MADS-box family members revealed that seven tandem and seven segmental duplication events had contributed to the expansion of the MADS-box gene family in hemp. Promoter analysis uncovered numerous cis-acting elements associated with light responsiveness, phytohormone signaling (including auxin and gibberellin), and environmental stress responses. Transcriptomic profiling showed that most CsaMADS-box genes are highly expressed in floral tissues, supporting their roles in reproductive development. Notably, a SOC1-like gene, CsaSOC1, was identified as a potential flowering integrator, and its physical interaction with CsaFUL was confirmed by yeast two-hybrid and luciferase complementation assays. Together, these results provide a comprehensive genomic overview of the MADS-box gene family in hemp and establish a valuable foundation for future functional studies of flowering regulation.

In this study, we investigated the changes in the communities of arbuscular mycorrhizal fungi (AMF) and their driving factors across eight vegetation succession stages in the Sanjiang Plain, Northeast China, original natural wetland (NW), wetland edge (EW), shrub-invaded wetland (IW), shrub-dominated wetland (DW), young-Betula forest (YB), mature-Betula forest (MB), Populus and Betula mixed forest (PB), and conifer forest (CF), using Illumina MiSeq sequencing. As this research has revealed, significant differences exist in soil physicochemical indicators, including moisture content (MC), pH, soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN), total phosphorus (TP), and available phosphorus (AP). As vegetation succession progresses, the diversity and structure of AMF communities also undergo changes, with the Simpson diversity index being highest in coniferous forests (CF) and the Abundance-based Coverage Estimator (ACE) and Chao1 indices being elevated in shrub-dominated wetlands (PB). Non-metric multidimensional scaling (NMDS) analysis reveals distinct differences in AMF communities across various succession stages. Furthermore, stacked bar charts indicate that the genus Glomus dominates in most wetland and forest succession stages but is nearly absent in CF, where it is replaced by the genus Paraglomus. Canonical correspondence analysis (CCA) demonstrates that SOC has a more significant impact on AMF communities during the EW stage of succession, while AP and TP exert greater influence during the CF stage as well as the MB and YB stages. AN, on the other hand, plays a more prominent role in shaping AMF communities during the IW and NW stages. PICRUSt2 predictions reveal that enzymes such as alcohol dehydrogenase and L-aminoadipate-semialdehyde dehydrogenase are most abundant in YB, whereas pathways like 4-amino-2-methyl-5-diphosphomethylpyrimidine biosynthesis are most enriched in IW. These findings uncover the close interplay between soil physicochemical properties and AMF community dynamics, aiming to deepen our understanding of the relationships among soil physicochemical properties, AMF community changes, and succession dynamics in wetland and forest ecosystems.

Purpose: China has recently witnessed a significant rise in nitrogen (N) deposition associated with human activities, especially in temperate regions. Although much research has been conducted on aboveground biodiversity, the effects of long-term N deposition on the composition, function and variety of the soil microbiota (especially across seasons) have received less attention. Methods: We investigated the effects of varying levels of nitrogen deposition on the composition, function and diversity of soil microbiota (bacteria and fungi) in temperate natural wetlands in summer and winter using Illumina sequencing. N deposition are categorized into low N addition (LN: 40 kg N/ha yr-1) and high N addition (HN: 80 kg N/ha yr-1). Results: In both summer and winter, N deposition had a significant effect on bacterial alpha diversity. In contrast, fungal alpha diversity exhibited no significant change in either of the two seasons. Additionally, the diversity of the soil microbiota exhibited higher sensitivity to N deposition in winter compared to summer. During the summer months, nitrogen deposition significantly altered the relative abundance of bacterial phyla such as Acidobacteria, Myxococcota, Verrucomicrobia and Actinobacteria. In winter, bacterial phyla in the surface soil exhibited distinct changes in their relative abundance. Relative abundance of Epsilonbacteraeota was highest in plots without added nitrogen, whereas the N-treated plots exhibited the lowest abundances. In addition, the relative abundance of Ascomycota was significantly increased by the addition of N, whereas Mortierellomycota exhibited a significant decrease, with Basidiomycota exhibiting no significant effect. The results from the structural equation model (SEM) revealed that soil organic carbon (SOC) and total nitrogen (TN) exerted a significant influence on the composition of both bacterial and fungal communities in the soil, regardless of the season. Specifically, in the summer season, SOC and TN account for 87 % of the variation observed in bacterial diversity and 83 % of the variation in fungal diversity. Likewise, during the winter season, these factors explain 91 % of the changes in bacterial diversity and 88 % of the changes in fungal diversity. Conclusion: Our research findings have unveiled that bacterial communities display a heightened sensitivity to nitrogen (N) deposition compared to their fungal counterparts. This discovery emphasizes the crucial need to concurrently evaluate the responses of the soil microbiome to global changes across various seasons, highlighting the intricate interplay between microbial dynamics and environmental factors.

To investigate the effects of long-term elevated atmospheric CO2 (eCO2) on the distribution and stability of soil aggregates and microbial characteristics in wetland soils and to reveal the mechanisms by which eCO2 influences soil organic carbon (SOC) sequestration, a multi-temporal-scale eCO2 control experiment was conducted in the Sanjiang Plain wetland with treatments at ambient CO2 concentration (AC), 550 ppm, and 700 ppm CO2. Soil aggregate fractionation, phospholipid fatty acid (PLFA) analysis, and redundancy analysis (RDA) were used to analyze changes in aggregate size distribution, stability indices (MWD, GMD), microbial biomass, and community structure. The results showed that eCO2 significantly affected aggregate size distribution. Both short- and long-term exposure to low-concentration eCO2 reduced the proportion of large aggregates. Over time, the proportion of silt and clay particles increased, while microaggregates decreased. Although CO2 concentration did not directly affect MWD and GMD, long-term eCO2 significantly reduced soil aggregate stability. Microbial biomass and diversity were not sensitive to CO2 concentration but decreased significantly with prolonged exposure. In contrast, microbial community structure was significantly affected by both CO2 level and exposure duration. RDA indicated that, under short-term eCO2, aggregate fractions were positively correlated with microbial biomass, whereas, under medium- and long-term treatments, they were positively correlated with soil physicochemical properties. Macroaggregates were positively correlated with aggregate stability, while microaggregates and silt–clay fractions were negatively correlated—a relationship that strengthened with longer eCO2 exposure. Thus, long-term eCO2 altered soil aggregate structure and microbial communities, ultimately influencing SOC stability. These findings provide data and theoretical support for predicting soil carbon stability and ecosystem functioning in wetlands under climate change.

Soil extracellular enzyme activity (EEAs) and enzymatic stoichiometry (ES) can provide a crucial indication of changes in soil ecosystem's nutrient availability and the microbial resource limitations. However, the changing characteristics of soil EEAs and ES at different stages of the native succession process and their key drivers are unclear. In order to investigate the soil EEAs, ES and driving factors of soil under vegetation at different succession stages, we adopted the "spatio-temporal substitution" method to collect the surface soil of bryophyte community, herbaceous community, shrub community and tree community in the new volcanic lava platform of Wudalianchi Volcanic Nature Reserve. We measured seven soil EEA, including carbon(C)-acquiring enzyme (β-1,4-glucosidase (BG)), N-acquiring enzymes (β-N-acetyl-glucosaminidase (NAG) and leucine aminopeptidase (LAP)) and phosphorus (P)-acquiring enzyme (acid phosphatase (AP)) activities. The length and angle of vectors defined by ratios of enzyme activities (BG/(NAG + LAP) vs. BG/AP) were used to indicate relative microbial investments in C- (length), and N- and P- (angle) acquiring enzymes. Our results showed that the contents of TC, TN, TP, MBC, DOC and NO3-N in shrub community soil were significantly higher than those in bryophyte, herb and tree communities, and increased by 441%, 246%, 137%, 5570%, 12% and 484%, respectively. The highest soil EEA of C-, N- and P-acquiring were found in shrub community, and the soil EEAs/MBC of C-, N- and P-acquiring were the highest in bryophyte community. Enzyme C:N, C:P and N:P ratios increased progressively in the order of bryophyte, herb and shrub community, but the enzyme C:N, C:P and N:P ratios of tree community were both far less than shrub community. Vector lengths increased progressively in the order of bryophyte (1.16), herb (1.27), tree (1.29) and shrub (1.40), and Vector angles decreased progressively in the order of bryophyte (49.15°), herb (45.65°), Tree (45.31°) and shurb (44.54°), suggested that as succession progresses, soil microbial nutrients transforms from P limitation (angle＞45°) to N limitation (angle＜45°). Redundancy analysis showed that TC, TN, EC and C:N were important drivers of variation in soil EEAs and ES in vegetation at different succession stages. Our findings highlight that the primary succession process cause nutrient limitation transformation. Soil ES might be a sensitive indicator mediated by soil microorganisms to the relative resource limitation at different stages of the primary succession process.

Shrub invasion affects plant growth and soil physicochemical properties, resulting in soil microbiota metabolic pathway changes. However, little is known about the shrub expansion intensity of microbial metabolic pathway processes. In this study, we used metagenome sequencing technology to investigate changes in soil microbial C and N metabolic pathways and community structures, along with different shrub invasion intensities, in the Sanjiang Plain wetlands. Different shrub invasion intensities significantly affected the soil microbial composition (β diversity), with no significant effect on the α diversity compared to CK. AN, pH, and TP were the major factors influencing the microbial community’s structures. Compared to CK, the shrub expansion intensity did not significantly affect C fixation and central metabolism but significantly reduced methanogenesis, which involves the CO2-to-methane transition that occurs in methane metabolism, and denitrification, the nitrite to nitric oxide (nirK or nirS) transition that occurs in N metabolism. This study provides an in-depth understanding of the biogeochemical cycles of wetland ecosystems in cold northern regions undergoing shrub invasion.

China has experienced a notorious increase in nitrogen (N) deposition as a result of anthropogenic activities, particularly in temperate areas. While aboveground biodiversity has been extensively studied, the impact of long-term N deposition on the diversity, composition, and function of the soil microbiome remains largely unexplored. In this study, we evaluated alterations in the diversity, composition, and function of soil bacterial and fungal communities in response to varying levels of N deposition (LN = low N addition, 40 kg N ha −1 yr −1 ; HN = high N addition, 80 kg N ha −1 yr −1 ) using Illumina MiSeq sequencing technology in a temperate natural wetland. N deposition had no discernible impact on bacterial α diversity, whereas fungal α diversity exhibited a significant decrease in response to high N addition only. Additionally, N deposition led to a notable increase in the relative abundance of the bacterial phylum Patescibacteria but a decrease in Latescibacteria. The relative abundance of Epsilonbacteraeota was highest in the unamended plots and lowest in the low N addition plots. Furthermore, N addition significantly increased the relative abundance of Ascomycota while decreasing that of Mortierellomycota, with no significant effect observed on Basidiomycota. Structural equation modeling (SEM) indicated that soil organic carbon (SOC), and total and available N were the two primary drivers shaping bacterial and fungal communities. Our study demonstrated that bacterial communities were less responsive to N addition compared to fungal communities, emphasizing the significance of simultaneously evaluating the soil microbiome in response to global changes.

Hydrological connectivity is crucial for the healthy operation of wetland ecosystems. However, the current design of ecological corridors in wetland biodiversity networks is mostly based on species migration resistance, neglecting the important role of hydrological connectivity. How to incorporate hydrological connectivity into the wetland ecological corridor system (ECS) is still unclear. To answer the question, we proposed a framework for constructing a wetland ECS with the goal of improving conservation value of previously identified wetland biodiversity hotspots based on hydrological connectivity. In the proposed framework, we clarified the function-level-dimension of each corridor based on the dynamics of conservation value of biodiversity hotspots, the hierarchical classification of rivers and the dimension of hydrological connectivity. Then we determined the spatial distribution and functional zoning of the corridors by least cost model (LCM) using indicators that reflect wetland hydrological connectivity resistance, including water coverage, water use efficiency of vegetation, and land use suitability. The results are as follows: (1) to improve the overall hydrological connectivity and conservation value of biodiversity hotspots, 25 corridors should be constructed for vertical hydrological connectivity (with 3 for maintaining the status quo, 6 for improving and 16 for restoring connectivity) and 3 corridors should be constructed for lateral hydrological connectivity; (2) total area of all corridors are 11 km2, accounting for 6.79% of the study area (2.47% of core zone and 4.32% of buffer zone); (3) low suitability areas of hydrological vegetation gradient (HVG) are the most extensive, followed by low suitability areas of land use/cover change (LUCC) and the average fraction coverage of water surface (AFCW), accounting for 65.08%, 47.87% and 6.76% of the corridor coverage, respectively. The proposed framework of constructing wetland ECS in this study has the potential to provide the post-2020 global biodiversity framework and sustainable development goals with specific technical support and more targeted-control strategies for building a hydrological connected wetland biodiversity network.

Soil microorganisms are pivotal in global biogeochemical cycles, significantly influencing energy flow and climate regulation. The Deyeuxia angustifolia wetland in the Sanjiang Plain, northeastern China, represents a key ecological area, yet the impact of organic nitrogen (Urea) addition on its soil microbial community remains largely unexplored. This study delves into the assembly patterns and processes of soil microbial communities following seven years of urea addition in this wetland, utilizing high-throughput sequencing technology. Our findings reveal that urea addition leads to a decrease in soil pH and an increase in various soil nutrients, including dissolved organic carbon, total nitrogen, organic carbon, dissolved organic nitrogen, nitrate, and ammonia nitrogen. While urea addition significantly alters soil bacterial and fungal beta-diversity, it does not affect their alpha-diversities. Comparative analysis across nitrogen treatments shows significant shifts in 24 bacterial and 21 fungal taxa. The abundance of a few bacterial genera (Bradyrhizobium and Haliangium) decreases with increasing N addition; while the abundance of a few fungal genera (Penicillium and Coniochaeta) increases with the increasing N addition. Random forest models revealed that rare genera (e.g., Syntrophorhabdus, Terrimonas, Galerina, and Mariannaea) also play an important role during organic nitrogen addition. Co-occurrence network analysis indicates a weakening interaction between bacteria and fungi with increased urea addition, accompanied by shifts in dominant bacterial and fungal phyla. Mantel test revealed a correlation between bacterial community diversity, network topology properties and various soil physico-chemical properties, while only network topology properties were correlated with soil physicochemical properties in the fungal community. Structural equation modeling (SEM) suggested that organic nitrogen addition affect soil bacterial and fungal structure by influencing plant diversity, plant biomass, and environmental factors. Community assembly analysis reveals a stochastic dominance in bacterial communities and a deterministic dominance in fungal communities under urea addition. Overall, this study enhances our understanding of soil microbial community responses to organic nitrogen addition in wetland ecosystems, offering insights for their sustainable management.

From connected sensors in soils, on animals or crops, and on drones, to various software and services that are available, "smart" technologies are changing the way farming is carried out. These technologies allow producers to look beyond what the eye can see by collecting non-traditional data and then using analytics tools to improve both food sustainability and profitability. "Smart Agriculture/farming" (SA) or "Digital Agriculture" (DA), often used interchangeably, refer to precision agriculture that is thus connected in a network of sensing and acting. It is a concept that employs modern information technologies, precision climate information, and crop/livestock developmental information to connect production variables to increase the quantity and quality of agricultural and food products. This is achieved by measuring and analyzing variables accurately, feeding the information into the cloud from edge devices, extracting trends from the various data, and subsequently providing information back to the producer in a timely manner. Smart agriculture covers many disciplines, including biology, mechanical engineering, automation, machine learning, artificial intelligence, and information technology-digital platforms. Minimum standards have been proposed for stakeholders with the aim to move toward this highly anticipated and ever-changing revolution. These foundational standards encompass the following general categories, including precise articulation of objectives, and baseline standards for the Internet of Things (IoT), including network infrastructure (e.g., stable 4G or 5G networks or a wireless local area network (WLAN) are available to end users). To sum up, SA aims to improve production efficiency, enhance the quality and quantity of agricultural products, reduce costs, and improve the environmental footprint of the industry. SA's ecosystem should be industry self-governed and collaboratively financed. SA stakeholders and end-users' facilities should meet standard equipment requirements, such as sensor accuracy, end data collectors, relevant industry compliant software, and trusted data analytics. The SA user is willing to be part of the SA ecosystem. This short perspective aims to summarize digital/smart agriculture concept in plain language.

In recent years, the Sanjiang Plain has experienced drastic human activities, which have dramatically changed its ecological environment. Soil microorganisms can sensitively respond to changes in soil quality as well as ecosystem function. In this study, we investigated the changes in soil microbial community diversity and composition of three typical land use types (forest, wetland and cropland) in the Sanjiang Plain using phospholipid fatty acid analysis (PLFA) technology, and 114 different PLFA compounds were identified. The results showed that the soil physicochemical properties changed significantly (p < 0.05) among the different land use types; the microbial diversity and abundance in cropland soil were lower than those of the other two land use types. Soil pH, soil water content, total organic carbon and available nitrogen were the main soil physico-chemical properties driving the composition of the soil microbial community. Our results indicate that the soil microbial community response to the three different habitats is complex, and provide ideas for the mechanism by which land use changes in the Sanjiang Plain affect the structure of soil microbial communities, as well as a theoretical basis for the future management and sustainable use of the Sanjiang plain, in the northeast of China.

To understand the role of microorganisms in litter decomposition and nutrient cycling in volcanic forest ecosystem, we conducted in-situ litterbag decomposition experiment and used Illumina MiSeq high-throughput sequencing to analyze the response of bacterial community structure and diversity during the decomposition of litters from Larix gmelinii, Betula platyphylla and Populus davidiana, the dominant tree species in volcanic lava plateau of Wudalianchi. The results showed that mass remaining percentage of litters of three species after 18-month decomposition was 63.9%-68.1%. Litter of B. platyphylla decomposed the fastest, with significant difference in N, C:N, and N:P before and after decomposition. The richness of bacterial species and diversity index differed significantly among the three litters. Proteobacteria, Actinomycetes, and Bacteroidetes were the dominant bacterial groups at the phylum level, while Rhizobium, Sphingomonas, and Pseudomonas were the dominant groups at the genus level, with significant difference among the three litters. After 18 months, the dominant bacterial groups in litter tended to be consistent with those in volcanic lava platform soil. In the volcanic forest ecosystem, bacterial diversity and community structure were mainly affected by P, C:N, and N:P in the litter.

Plants utilize different strategies in different environments to maximize population expansion. Understanding plant reproductive strategies in heterogeneous habitats is therefore important for explaining plant ecological adaptability, and for effectively managing and conserving ecosystems. We wanted to explore the reproductive strategy transformation of D. angustifolia in heterogeneous habitats, as well as the environmental factors driving and affecting its reproductive characteristics. To do this we measured the reproductive characteristics of D. angustifolia, as well as the soil physical and chemical properties of these heterogeneous habitats. The density, biomass per unit area, and proportion of aboveground biomass in swampy meadows were significantly higher compared to other habitats. The proportion of rhizome node buds gradually increased from swampy to typical to miscellaneous grass meadows, while the proportion of tillering node buds decreased. The allocation of sexual reproduction within D. angustifolia populations was significantly and positively correlated with plant rhizome biomass and negatively correlated with the number of tillering node buds. The propagation strategies of D. angustifolia in heterogeneous habitats were consistent with CSR theory (Competitor, Stress-tolerator, and Ruderal). The proportions of inflorescence (2.07 ± 0.52%; 1.01 ± 0.15%) and root (23.8 ± 1.5%; 19.6 ± 1.4%) biomass in miscellaneous and typical meadows were high, which tended toward the “Ruderal” adaptation strategy. In swampy meadow, D. angustifolia invested mostly in vegetative growth to produce tiller node buds (14426.67 buds/m2; 46%) and ramets (1327.11 ± 102.10 plants/m2), which is characteristic of the “Competitor” strategy. Swamp D. angustifolia resisted flooding by maintaining a resource balance in its body, and was therefore biased toward the “Stress-tolerator” strategy. Environmental factors accounted for 74.63% of reproductive characteristic variation, in which the interpretative proportions of soil water content, dissolved organic carbon, ammonia nitrogen, and nitrate nitrogen were significant (p < 0.01). When soil water content, dissolved organic carbon, and nitrate nitrogen increased, D. angustifolia tended toward the C strategy; in contrast, when soil water content decreased, amine nitrogen and available phosphorus increased, and D. angustifolia tended toward the R strategy. In a stressful environment, the escape mechanism constitutes an increased rhizome and sexual reproduction investment. In contrast, for suitable habitats, tillering node buds increased in order to expand the population via new plant production, which was the propagation strategy of D. angustifolia in heterogeneous habitats.

Deyeuxia angustifolia is a dominant plant in typical marshy wetlands in Sanjiang Plain. Through in situ field control experiments, the adaptability and response law of the species to the nitrogen addition level and nitrogen form were studied, providing a scientific basis for predicting the change in the wetland vegetation population after an increase in the atmospheric nitrogen deposition flux and the change in the nitrogen form. Three nitrogen forms were tested in the experiment with nitrate nitrogen, ammonium nitrogen, and organic nitrogen, with three nitrogen addition levels [4, 8, and 12 g·(m2·a)−1], and a control (no nitrogen added). A total of ten treatments were used to analyze the differences in the functional properties of D. angustifolia. The results showed that, under the action of nitrate nitrogen and ammonium nitrogen, the basal diameter, internode length, leaf number, aboveground biomass, and stem and leaf biomass of D. angustifolia increased with the increase in the nitrogen application rate. Under the medium and high nitrogen levels, ammonium nitrogen mainly promoted stem growth, nitrate nitrogen had a significant impact on leaf growth, and organic nitrogen had a significant impact on the branch number and leaf number of D. angustifolia (P < 0.05). The number of internodes, branches, leaves, and biomass increased with the increase in inorganic nitrogen, while organic nitrogen followed the opposite trend. After applying nitrogen, the leaf biomass of D.angustifolia increased. Conclusion: The tolerance range of D. angustifolia to organic nitrogen is small, but that to inorganic nitrogen is large. Nitrogen application can promote the growth and biomass accumulation of D.angustifolia in Sanjiang Plain, increase the proportion of leaf biomass, and decrease the proportion of stem and tassel biomass.

N deposition is a key factor affecting the composition and function of soil microbial communities in wetland ecosystems. Previous studies mainly focused on the effects of N deposition in the soil during the growing season (summer and autumn). Here, we focused on the response of the soil microbial community structure and function in winter. Soil from the Sanjiang Plain wetland, China, that had been treated for the past 11 years by using artificial N deposition at three levels (no intervention in N0, N deposition with 4 g N m−2 yr−1 in N1, and with 8 g N m−2 yr−1 in N2). Soil characteristics were determined and the bacterial composition and function was characterized using high-throughput sequence technology. The N deposition significantly reduced the soil bacterial diversity detected in winter compared with the control N0, and it significantly changed the composition of the bacterial community. At the phylum level, the high N deposition (N2) increased the relative abundance of Acidobacteria and decreased that of Myxococcota and Gemmatimonadota compared with N0. In soil from N2, the relative abundance of the general Candidatus_Solibacter and Bryobacter was significantly increased compared with N0. Soil pH, soil organic carbon (SOC), and total nitrogen (TN) were the key factors affecting the soil bacterial diversity and composition in winter. Soil pH was correlated with soil carbon cycling, probably due to its significant correlation with aerobic_chemoheterotrophy. The results show that a long-term N deposition reduces soil nutrients in winter wetlands and decreases soil bacterial diversity, resulting in a negative impact on the Sanjiang plain wetland. This study contributes to a better understanding of the winter responses of soil microbial community composition and function to the N deposition in temperate wetland ecosystems.

The soil microbiome is an important component of wetland ecosystems and plays a pivotal role in nutrient cycling and climate regulation. Nitrogen (N) addition influences the soil’s microbial diversity, composition, and function by affecting the soil’s nutrient status. The change in soil bacterial diversity and composition in temperate wetland ecosystems in response to high ammonium nitrogen additions remains unclear. In this study, we used high-throughput sequencing technology to study the changes of soil bacterial diversity and community structure with increasing ammonium concentrations [CK (control, 0 kg ha−1 a−1), LN (low nitrogen addition, 40 kg ha−1 a−1), and HN (high nitrogen addition, 80 kg ha−1 a−1)] at a field experimental site in the Sanjiang Plain wetland, China. Our results showed that except for soil organic carbon (SOC), other soil physicochemical parameters, i.e., soil moisture content (SMC), dissolved organic nitrogen (DON), total nitrogen (TN), pH, ammonium nitrogen (NH4+), and dissolved organic carbon (DOC), changed significantly among three ammonium nitrogen addition concentrations (p < 0.05). Compared to CK, LN did not change soil bacterial α-diversity (p > 0.05), and HN only decreased the Shannon (p < 0.05) and did not change the Chao (p > 0.05) indices of soil bacterial community. Ammonium nitrogen addition did not significantly affect the soil’s bacterial community structure based on non-metric multidimensional scaling (NMDS) and PERMANOVA (ADONIS) analyses. Acidobacteriota (24.96–31.11%), Proteobacteria (16.82–26.78%), Chloroflexi (10.34–18.09%), Verrucomicrobiota (5.23–11.56%), and Actinobacteriota (5.63–8.75%) were the most abundant bacterial phyla in the soils. Nitrogen addition changed the complexity and stability of the bacterial network. SMC, NO3−, and pH were the main drivers of the bacterial community structure. These findings indicate that enhanced atmospheric nitrogen addition may have an impact on bacterial communities in soil, and this study will allow us to better understand the response of the soil microbiome in wetland ecosystems in the framework of increasing nitrogen deposition.