Impacts of litter microbial community on litter decomposition in the absence of soil microorganisms.

What is the effect of phyllosphere microorganisms on litter decomposition in the absence of colonization by soil microorganisms? Here, we simulated the litter standing decomposition stage in the field to study the differences in the composition and structure of the phyllosphere microbial community after the mixed decomposition of Populus × canadensis and Pinus sylvestris var. mongolica litter. After 15 months of mixed decomposition, we discovered that litters that were not in contact with soil had an antagonistic effect (the actual decomposition rate was 18.18%, which is lower than the expected decomposition rate) and the difference between the litters themselves resulted in a negative response to litter decomposition. In addition, there was no significant difference in bacterial and fungal community diversity after litter decomposition. The litter bacterial community was negatively responsive to litter properties and positively responsive to the fungal community. Importantly, we found that bacterial communities had a greater impact on litter decomposition than fungi. This study has enriched our understanding of the decomposition of litter itself and provided a theoretical basis for further exploring the "additive and non-additive effects" of litter decomposition and the mechanism of microbial drive. IMPORTANCE: The study of litter decomposition mechanism plays an important role in the material circulation of the global ecosystem. However, previous studies have often looked at contact with soil as the starting point for decomposition. But actually, standing litter is very common in forest ecosystems. Therefore, we used field simulation experiments to simulate the decomposition of litters without contact with soil for 15 months, to explore the combined and non-added benefits of the decomposition of mixed litters, and to study the influence of microbial community composition on the decomposition rate while comparing the differences of microbial communities.

Signal-enhanced multi-core fiber-based WaveFlex biosensor for ultra-sensitive xanthine detection.

In this work, we introduce a novel multimode fiber (MMF) - seven core fiber (SCF) - MMF (MCM) optical fiber biosensor, also known as the WaveFlex biosensor (plasma wave assisted fiber biosensor), based on localized surface plasmon resonance (LSPR) for qualitative detection of xanthine. Xanthine is a purine base widely distributed in human blood and tissues, and commonly used as an indicator for various disease detections. The MCM sensor incorporates a tapered optical fiber structure, fabricated using the combiner manufacturing system (CMS), and is designed with SCF and MMF. By effectively harnessing LSPR, the sensor boosts the attachment points of biomolecules on the probe surface through immobilized tungsten disulfide (WS2)-thin layers, gold nanoparticles (AuNPs), and carbon nitride quantum dots (C3N-QDs). The functionalization of xanthine oxidase (XO) on the sensing probe further enhances the sensor's specificity. The proposed WaveFlex biosensor exhibits a remarkable sensitivity of 3.2 nm/mM and a low detection limit of 96.75 µM within the linear detection range of 100 - 900 µM. Moreover, the sensor probe demonstrates excellent reusability, reproducibility, stability, and selectivity. With its sensitivity, biocompatibility, and immense potential for detecting human serum and fish products, this WaveFlex biosensor presents a promising platform for future applications.

Variations of Phyllosphere and Rhizosphere Microbial Communities of Pinus koraiensis Infected by Bursaphelenchus xylophilus.

Pine wood nematode, Bursaphelenchus xylophilus, as one of the greatest threats to pine trees, is spreading all over the world. Plant microorganisms play an important role in the pathogenesis of nematodes. The phyllosphere and rhizosphere bacterial and fungal communities associated with healthy Pinus koraiensis (PKa) and P. koraiensis infected by B. xylophilus at the early (PKb) and last (PKc) stages were analyzed. Our results demonstrated that pine wood nematode (PWD) could increase the phyllosphere bacterial Pielou_e, Shannon, and Simpson index; phyllosphere fungal Chao 1 index, as well as rhizosphere bacterial Pielou_e, Shannon, and Simpson index; and rhizosphere fungal Pielou_e, Shannon, and Simpson index. What's more, slight shifts of the microbial diversity were observed at the early stage of infection, and the microbial diversity increased significantly as the symptoms of infection worsened. With the infection of B. xylophilus in P. koraiensis, Bradyrhizobium (rhizosphere bacteria), Massilia (phyllosphere bacteria), and Phaeosphaeriaceae (phyllosphere fungi) were the major contributors to the differences in community compositions among different treatments. With the infection of PWD, most of the bacterial groups tended to be co-excluding rather than co-occurring. These changes would correlate with microbial ability to suppress plant pathogen, enhancing the understanding of disease development and providing guidelines to pave the way for its possible management.

Individual and combined effects of salinity and lipopolysaccharides on the immune response of juvenile Takifugu fasciatus.

Lipopolysaccharides (LPS) and salinity are important variables in aquatic environments. High concentration of LPS and large changes in salinity seriously threat the survival of a variety of organisms, including fish. To reveal the effects of salinity and LPS on a fish immune response, we measured the immune-related parameters (total leukocyte count, total serum protein, albumin and globulin concentrations, complement C3 concentration, and lysozyme activity) and genes (the expressions of TNF-α, IL-1ß, and SOCS1-3 at the mRNA and protein levels) of juvenile Takifugu fasciatus exposed to phosphate buffered saline (PBS) or LPS (25 µg mL-1) under different salinities (0, 15, and 30 ppt) for 24 h. Changes in key immunological indicators suggested that the LPS challenge induced considerable damage to T. fasciatus, whereas an increase in salinity mitigated the harmful effects. Moreover, although the immune responses in blood and other selected tissues (gill and kidney) were suppressed with an increase in salinity, the increased response in liver in saltwater enabled T. fasciatus to conquer large salinity variation during migration. The appropriate addition of salts appeared to be a sensible strategy to mitigate LPS-induced toxicity in the aquaculture of T. fasciatus.

The improved energy metabolism and blood oxygen-carrying capacity for pufferfish, Takifugu fasciatus, against acute hypoxia under the regulation of oxygen sensors.

Hypoxia frequently occurs in aquatic ecosystem, which is influenced by salinity, water temperature, weather, and surface water runoff. In order to shed further light on the evolutionary and adaptive mechanisms in fish under hypoxic condition, the impact of acute hypoxia (1.63 ± 0.2 mg/L) and reoxygenation (7.0 ± 0.3 mg/L) on oxygen sensors, energy metabolism, and hematological indices was evaluated in Takifugu fasciatus. Data from transcriptional level analysis show that the expressions of genes related to oxygen sensors (HIF-1α, PHD2, and VHL) were upregulated in the brain and liver under hypoxia and recovered under reoxygenation. The upregulation of GLUT2, VEGF-A, and EPO in conjugation with VEGF-A protein and hematological indices conferred the rapid adjustments of cellular glucose uptake and blood oxygen-carrying capacities in pufferfish. Higher levels of glycolysis-related mRNAs (HK, PGK1, and PGAM2), HK activity, and proteins (PGK1 and PGAM2) were detected in the brain and liver under hypoxic condition compared with control. Interestingly, the expression of MDH1 at the mRNA, enzyme activity, and protein levels was significantly increased in the brain at 0 or 2 h and in the liver at 8 h under hypoxic condition. In addition, although the enzyme activity and mRNA expression of LDH in the brain were not significantly changed, a persistent upregulation was observed in the liver during hypoxia exposure. This study demonstrated that pufferfish could counterpoise the energetic demands and hematological functional properties evoked by oxygen sensors after hypoxia. Our findings provided new insights into the molecular regulatory mechanism of hypoxia in pufferfish.

Intercropping changed the soil microbial community composition but no significant effect on alpha diversity.

Introduction: Enhancing the planning of the forest-agricultural composite model and increasing the efficiency with which forest land is utilized could benefit from a thorough understanding of the impacts of intercropping between forests and agriculture on soil physicochemical properties and microbial communities. Methods: Populus cathayana × candansis cv. Xinlin No.1 and Glycine max intercrop soils, along with their corresponding monocrops, were used in this study's llumina high-throughput sequencing analysis to determine the composition and diversity of soil bacterial and fungal communities. Results: The findings indicated that intercropping considerably raised the soil's total phosphorus content and significantly lowered the soil's carbon nitrogen ratio when compared to poplar single cropping. Furthermore, the total carbon and nitrogen content of soil was increased and the soil pH was decreased. The sequencing results showed that intercropping had no significant effect on soil alpha diversity. Intercropping could increase the composition of fungal community and decrease the composition of bacterial community in poplar soil. At the phylum level, intercropping significantly increased the relative abundance of four dominant phyla, i.e., Patescibacteria, Proteobacteria, Patescibacteria and Deinococcus-Thermus. And the relative abundances of only two dominant phyla were significantly increased. It was found that soil total phosphorus and available phosphorus content had the strongest correlation with soil bacterial community diversity, and soil pH had the strongest correlation with soil fungal community diversity. Discussion: The results of this study were similar to those of previous studies. This study can serve as a theoretical foundation for the development of a poplar and black bean-based forest-agricultural complex management system in the future.

Assessment of the Fruit Chemical Characteristics and Antioxidant Activity of Different Mulberry Cultivars (Morus spp.) in Semi-Arid, Sandy Regions of China.

As a traditional cash crop with ecological and nutritional values, mulberry is gradually expanding its consumption worldwide due to its great regional adaptability and superior health functions. The widespread interest in nutrients has led to a growing need to explore in depth the health benefits of mulberries. Many studies are actively being conducted to investigate the adaptability of the diversity of mulberries in different applications. This study systematically investigated the physicochemical properties and antioxidant activity of four mulberry genotypes cultivated in China's semi-arid sandy regions to better understand the composition and health-promoting potential of this super crop. Chemical composition identification was identified via HPLC and antioxidant activity was further determined via DPPH and FRAP. The moisture, crude protein, ash, soluble solids, phenolics, anthocyanins, and flavonoids contents of mulberry were comparatively analyzed. The study revealed that the four mulberry genotypes showed significant differences in quality and content of the analyzed characteristics. The greatest antioxidant activity was found in Shensang 1, which had the most soluble solids (17%) and the highest amounts of free sugar (fructose: 5.14% and glucose: 5.46%). Ji'an had the most minerals (K: 2.35 mg/g, Ca: 2.27 mg/g, and Fe: 467.32 mg/kg) and it also contained chlorogenic acid, which has the potential to be turned into a natural hypoglycemic agent. PCA and Pearson correlation analysis indicated that the antioxidant activity was closely related to the chemical contents of total phenols, flavonoids, anthocyanins, and soluble sugars. If the antioxidant activity and nutrient content of the developed plants are considered, Shen Sang 1 is the most favorable variety. This finding can be used to support the widespread cultivation of mulberries to prevent desertification as well as to promote the development of the mulberry industry.

Characteristics of Soil Physicochemical Properties and Microbial Community of Mulberry (Morus alba L.) and Alfalfa (Medicago sativa L.) Intercropping System in Northwest Liaoning.

Medicinal plant intercropping is a new intercropping method. However, as a new intercropping model, the influence of intercropping of alfalfa on microorganisms has not been clarified clearly. In this study, the composition and diversity of microbial communities in alfalfa intercropping were studied, and the differences of bacterial and fungal communities and their relationships with environmental factors are discussed. Intercropping significantly decreased soil pH and significantly increased soil total phosphorus (TP) content, but did not increase soil total carbon (TC) and total nitrogen (TN). Intercropping can increase the relative abundance of Actinobacteria and reduce the relative abundance of Proteobacteria in soil. The relative abundance and diversity of bacteria were significantly correlated with soil pH and TP, while the diversity of fungi was mainly correlated with TC, TN and soil ecological stoichiometry. The bacterial phylum was mainly related to pH and TP, while the fungal phylum was related to TC, TN, C: P and N: P. The present study revealed the stoichiometry of soil CNP and microbial community characteristics of mulberry-alfalfa intercropping soil, clarified the relationship between soil stoichiometry and microbial community composition and diversity, and provided a theoretical basis for the systematic management of mulberry-alfalfa intercropping in northwest Liaoning.

Similarities and differences in the microbial structure of surface soils of different vegetation types.

Background: Soil microbial community diversity serves as a highly sensitive indicator for assessing the response of terrestrial ecosystems to various changes, and it holds significant ecological relevance in terms of indicating ecological alterations. At the global scale, vegetation type acts as a major driving force behind the diversity of soil microbial communities, encompassing both bacterial and fungal components. Modifications in vegetation type not only induce transformations in the visual appearance of land, but also influence the soil ecosystem's material cycle and energy flow, resulting in substantial impacts on the composition and performance of soil microbes. Methods: In order to examine the disparities in the structure and diversity of soil microbial communities across distinct vegetation types, we opted to utilize sample plots representing four specific vegetation types. These included a woodland with the dominant tree species Drypetes perreticulata, a woodland with the dominant tree species Horsfieldia hainanensis, a Zea mays farmland and a Citrus reticulata fields. Through the application of high-throughput sequencing, the 16S V3_V4 region of soil bacteria and the ITS region of fungi were sequenced in this experiment. Subsequently, a comparative analysis was conducted to explore and assess the structure and dissimilarities of soil bacterial and fungal communities of the four vegetation types were analyzed comparatively. Results: Our findings indicated that woodland soil exhibit a higher richness of microbial diversity compared to farmland soils. There were significant differences between woodland and farmland soil microbial community composition. However, all four dominant phyla of soil fungi were Ascomycota across the four vegetation types, but the bacterial dominant phyla were different in the two-farmland soil microbial communities with the highest similarity. Furthermore, we established a significant correlation between the nutrient content of different vegetation types and the relative abundance of soil microorganisms at both phyla and genus levels. This experiment serves as a crucial step towards unraveling the intricate relationships between plants, soil microbes, and soil, as well as understanding the underlying driving mechanism.

The Changes of Phyllosphere Fungal Communities among Three Different Populus spp.

As an ecological index for plants, the diversity and structure of phyllosphere microbial communities play a crucial role in maintaining ecosystem stability and balance; they can affect plant biogeography and ecosystem function by influencing host fitness and function. The phyllosphere microbial communities reflect the immigration, survival, and growth of microbial colonists, which are influenced by various environmental factors and leaves' physical and chemical properties. This study investigated the structure and diversity of phyllosphere fungal communities in three different Populus spp., namely-P. × euramaricana (BF3), P. nigra (N46), and P. alba × P. glandulosa (84K). Leaves' chemical properties were also analyzed to identify the dominant factors affecting the phyllosphere fungal communities. N46 exhibited the highest contents of total nitrogen (Nt), total phosphorus (Pt), soluble sugar, and starch. Additionally, there were significant variations in the abundance, diversity, and composition of phyllosphere fungal communities among the three species: N46 had the highest Chao1 index and observed_species, while 84K had the highest Pielou_e index and Simpson index. Ascomycota and Basidiomycota are the dominant fungal communities at the phylum level. Results from typical correlation analyses indicate that the chemical properties of leaves, especially total phosphorus (Pt), total nitrogen (Nt), and starch content, significantly impact the structure and diversity of the phyllosphere microbial community. However, it is worth noting that even under the same stand conditions, plants from different species have distinct leaf characteristics, proving that the identity of the host species is the critical factor affecting the structure of the phyllosphere fungal community.

Differences in phyllosphere microbiomes among different Populus spp. in the same habitat.

Introduction: The above-ground parts of terrestrial plants are collectively known as the phyllosphere. The surface of the leaf blade is a unique and extensive habitat for microbial communities. Phyllosphere bacteria are the second most closely associated microbial group with plants after fungi and viruses, and are the most abundant, occupying a dominant position in the phyllosphere microbial community. Host species are a major factor influencing the community diversity and structure of phyllosphere microorganisms. Methods: In this study, six Populus spp. were selected for study under the same site conditions and their phyllosphere bacterial community DNA fragments were paired-end sequenced using 16S ribosomal RNA (rRNA) gene amplicon sequencing. Based on the distribution of the amplicon sequence variants (ASVs), we assessed the alpha-diversity level of each sample and further measured the differences in species abundance composition among the samples, and predicted the metabolic function of the community based on the gene sequencing results. Results: The results revealed that different Populus spp. under the same stand conditions resulted in different phyllosphere bacterial communities. The bacterial community structure was mainly affected by the carbon and soluble sugar content of the leaves, and the leaf nitrogen, phosphorus and carbon/nitrogen were the main factors affecting the relative abundance of phyllosphere bacteria. Discussion: Previous studies have shown that a large proportion of the variation in the composition of phyllosphere microbial communities was explained by the hosts themselves. In contrast, leaf-borne nutrients were an available resource for bacteria living on the leaf surface, thus influencing the community structure of phyllosphere bacteria. These were similar to the conclusions obtained in this study. This study provides theoretical support for the study of the composition and structure of phyllosphere bacterial communities in woody plants and the factors influencing them.

Calcium Regulates Growth and Nutrient Absorption in Poplar Seedlings.

As a crucial element for plants, calcium (Ca) is involved in photosynthesis and nutrient absorption, and affects the growth of plants. Poplar is an important economic forest and shelter forest species in China. However, the optimum calcium concentration for its growth is still unclear. Herein, we investigated the growth, biomass, photosynthetic pigments, photosynthetic parameters and products, chlorophyll fluorescence parameters, water use efficiency (iWUE), and antioxidant enzyme activity of "Liao Hu NO.1" poplar (P. simonii × P. euphratica) seedlings at 0, 2.5, 5, 10, and 20 mmol·L-1 concentrations of Ca2+, and further studied the absorption, distribution, and utilization of nutrient elements (C, N, P, K, and Ca) in plants. We found that with increasing calcium gradient, plant height and diameter; root, stem, leaf, and total biomasses; net photosynthetic rate (Pn); stomatal conductance (Gs); intercellular carbon dioxide (Ci) level; transpiration rate (Tr); Fv/Fm ratio; Fv/F0 ratio; chlorophyll-a; chlorophyll-b; soluble sugar and starch content; superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD) levels; and long-term water use efficiency (iWUE) of poplar seedlings first increased and then decreased. These parameters attained maximum values when the calcium concentration was 5 mmol·L-1, which was significantly different from the other treatments (P < 0.05). Moreover, a suitable Ca2+ level promoted the absorption of C, N, P, K, and Ca by various organs of poplar seedlings. The absorption of C, N, P, and K increased first and then decreased with the increased calcium concentration, but the optimum calcium concentrations for the absorption of different elements by different organs were different, and the calcium concentration in leaves, stems, and roots increased gradually. Furthermore, the increase in exogenous calcium content led to a decreasing trend in the C/N ratio in different organs of poplar seedlings. C/P and N/P ratios showed different results in different parts, and only the N/P ratio in leaves showed a significant positive correlation with Ca2+ concentration. In conclusion, the results of this study indicate that 5 mmol·L-1 concentration of Ca2+ is the optimal level, as it increased growth by enhancing photosynthesis, stress resistance, and nutrient absorption.

Physiological and comparative transcriptome analysis of the response and adaptation mechanism of the photosynthetic function of mulberry (Morus alba L.) leaves to flooding stress.

Flooding has become one of the major abiotic stresses that seriously affects plant growth and development owing to changes in the global precipitation pattern. Mulberry (Morus alba L.) is a desirable tree spePhysocarpus amurensis Maxim andcies with high ecological and economic benefits. To reveal the response and adaptive mechanisms of the photosynthetic functions of mulberry leaves to flooding stress, chlorophyll synthesis, photosynthetic electron transfer and the Calvin cycle were investigated by physiological studies combined with an analysis of the transcriptome. Flooding stress inhibited the synthesis of chlorophyll (Chl) and decreased its content in mulberry leaves. The sensitivity of Chl a to flooding stress was higher than that of Chl b owing to the changes of CHLG (LOC21385082) and CAO (LOC21408165) that encode genes during chlorophyll synthesis. The levels of expression of Chl b reductase NYC (LOC112094996) and NYC (LOC21385774), which are involved in Chl b degradation, were upregulated on the fifteenth day of flooding, which accelerated the transformation of Chl b to Chl a, and upregulated the expression of PPH (LOC21385040) and PAO (LOC21395013). This accelerated the degradation of chlorophyll. Flooding stress significantly inhibited the photosynthetic function of mulberry leaves. A Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis of differentially expressed genes under different days of flooding stress indicated significant enrichment in Photosynthesis-antenna proteins (map00196), Photosynthesis (map00195) and Carbon fixation in photosynthetic organisms (map00710). On the fifth day of flooding, 7 and 5 genes that encode antenna proteins were identified on LHCII and LHCI, respectively. They were significantly downregulated, and the degree of downregulation increased as the trees were flooded longer. Therefore, the power of the leaves to capture solar energy and transfer this energy to the reaction center was reduced. The chlorophyll fluorescence parameters and related changes in the expression of genes in the transcriptome indicated that the PSII and PSI of mulberry leaves were damaged, and their activities decreased under flooding stress. On the fifth day of flooding, electron transfer on the PSII acceptor side of mulberry leaves was blocked, and the oxygen-evolving complex (OEC) on the donor side was damaged. On the tenth day of flooding, the thylakoid membranes of mulberry leaves were damaged. Five of the six coding genes that mapped to the OEC were significantly downregulated. Simultaneously, other coding genes located at the PSII reaction center and those located at the PSI reaction center, including Cytb6/f, PC, Fd, FNR and ATP, were also significantly downregulated. In addition, the gas exchange parameters (Pn, Gs, Tr, and Ci) of the leaves decreased after 10 days of flooding stress primarily owing to the stomatal factor. However, on the fifteenth day of flooding, the value for the intracellular concentration of CO2 was significantly higher than that on the tenth day of flooding. In addition, the differentially expressed genes identified in the Calvin cycle were significantly downregulated, suggesting that in addition to stomatal factors, non-stomatal factors were also important factors that mediated the decrease in the photosynthetic capacity of mulberry leaves. In conclusion, the inhibition of growth of mulberry plants caused by flooding stress was primarily related to the inhibition of chlorophyll synthesis, antenna proteins, photosynthetic electron transfer and the Calvin cycle. The results of this study provide a theoretical basis for the response and mechanism of adaptation of the photosynthetic function of mulberry to flooding stress.

Characterization of ectomycorrhizal fungal communities associated with tree species on an iron tailings deposit undergoing restoration.

Vegetation restoration is an effective method to improve the ecological environment of mine tailings, which has a profound impact on the potential ecological functions of soil fungal communities; yet, little is known about its beneficial effect on soil ectomycorrhizal fungal community. In this study, the responses of soil characteristics and soil ectomycorrhizal fungal community diversity and structure to different revegetation, as well as the contribution of soil factors to soil ectomycorrhizal community were investigated in Liaoning Province, China. As we anticipated, the presence of vegetation significantly improved most soil properties we studied. What's more, compared to Korean pine (Pinus koraiensis Sieb. et Zucc.), Chinese poplar (Populus simonii Carr), and black locust (Robinia pseudoacacia L) could better improve soil total carbon, total nitrogen, total phosphorus, and available phosphorus. In addition, soil ectomycorrhizal fungal community diversity in black locust was greater than Korean pine and Populus simonii. Nonmetric multidimensional scaling analyses indicated that soil ectomycorrhizal community significantly differed depending on different revegetation types. Thus, these results indicated that black locust could be a suitable species for the revegetation of iron mine tailings. The study provided theoretical basis for ecological restoration of iron mine tailings using local plant species.

Litter mixing promoted decomposition rate through increasing diversities of phyllosphere microbial communities.

Decomposition of forest litter is an essential process for returning nutrients to the soil, which is crucial for preserving soil fertility and fostering the regular biological cycle and nutrient balance of the forest ecosystem. About 70% of the land-based forest litter is made up primarily of leaf litter. However, research on the complex effects and key determinants of leaf litter decomposition is still lacking. In this study, we examined the characteristics of nutrient release and microbial diversity structure during the decomposition of three types of litter in arid and semi-arid regions using 16S rRNA and ITS sequencing technology as well as nutrient content determination. It was revealed that the nutrient content and rate of decomposition of mixed litters were significantly different from those of single species. Following litter mixing, the richness and diversity of the microbial community on leaves significantly increased. It was determined that there was a significant correlation between bacterial diversity and content (Total N, Total P, N/P, and C/P). This study provided a theoretical framework for investigating the decomposition mechanism of mixed litters by revealing the microbial mechanism of mixed decomposition of litters from the microbial community and nutrient levels.

Effects of Mixed Decomposition of Pinus sylvestris var. mongolica and Morus alba Litter on Microbial Diversity.

Pinus sylvestris var. mongolica is widely planted in China as a windbreak and sand fixation tree. To improve the current situation of large-scale declines of forested areas planted as P. sylvestris var. mongolica monocultures, we investigated the biological and microbial effects of stand establishment using mixed tree species. The interactions during the mixed decomposition of the litter and leaves of different tree species are an important indicator in determining the relationships among species. In this experiment, a method of simulating the mixed decomposition of P. sylvestris var. mongolica and Morus alba litter under P. sylvestris var. mongolica forest was used to determine the total C, total N, and total P contents in the leaf litter, and the microbial structures were determined by using Illumina MiSeq high-throughput sequencing. It was found that with samples with different proportions of P. sylvestris var. mongolica and M. alba litters, the decomposition rate of P. sylvestris var. mongolica × M. alba litter was significantly higher than that of the pure P. sylvestris var. mongolica forest, and the microbial community and composition diversity of litter in a pure P. sylvestris var. mongolica forest could be significantly improved. The possibility of using M. alba as a mixed tree species to address the declines of pure P. sylvestris var. mongolica forest was verified to provide guidance for pure P. sylvestris var. mongolica forests by introducing tree species with coordinated interspecific relationships and creating a mixed forest.

Effects of afforestation with Pinus sylvestris var. mongolica plantations combined with enclosure management on soil microbial community.

Grazing and litter removal can alter understory structure and composition after afforestation, posing a serious threat to sustainable forest development. Enclosure is considered to be an effective measure to restore degraded forest restoration. However, little is known about the dynamics of soil nutrients and microbial communities during the forest restoration process. In the present study, the effects of Arachis hypogaea (AH), Pinus sylvestris var. mongolica (PSM) and Pinus sylvestris var. mongolica with enclosure (PSME) on soil chemical properties and soil microbial communities were studied in Zhanggutai, Liaoning Province, China. The results showed that PSME could remarkably contribute to improve soil total C, total N and total P compared to PSM and AH. Additionally, PSM could clearly increase the soil bacterial community diversity and fungal Chao1 index and ACE index. Additionally, PSME could further increase soil Chao1 index and ACE index of soil bacteria. Soil total C, total N and available N were the main factors related to soil microbial diversity. Actinobacteria and Ascomycota were the predominant bacterial and fungal phyla, respectively. Specifically, PSME could increase the relative abundances of Actinobacteria, Gemmatimonadetes, Ascomycota and Mortierellomycota and decreased the relative abundances of Acidobacteria, Chloroflexi and Basidiomycota than PSM. PSM and PSME could clearly change soil microbial communities compared with AH and PSME could remarkably shift soil fungal communities than PSM. What's more, the soil microbial community structure were affected by multiple edaphic chemical parameters. It can be seen that afforestation combined with enclosed management potentially regulate microbial properties through shifting the soil properties. This study can provide new ideas for further understanding the impact of enclosure on PSM and provide theoretical support for the management of PSM.

Variations of soil microbial communities accompanied by different vegetation restoration in an open-cut iron mining area.

Overexploitation of iron mining in China has caused serious environmental pollution. Therefore, establishing a stable ecological restoration with vegetation in mining areas has gradually aroused people's awareness and obtained extensive concerns. This study aimed to evaluate vegetation restoration with Robinia pseudoacacia (RP), Acer mono (AM) and Pinus koraiensis (PK) in iron mining compared with unrestored area, to investigate the soil environment factors and microbial communities, and to better understand the correlations between soil environment factors and soil microbial communities. Vegetation restoration could reduce soil pH and alleviate soil alkaline, and remarkably increase soil nutrients, especially in RP site. Analysis of 16S rRNA and ITS rRNA gene sequences provided a total of 645,004 and 906, 276 valid sequences clustered into 7091 OTUs and 1689 OTUs at a 0.03 genetic distance for bacteria and fungi, respectively. The predominant bacterial and fungal phyla were Actinobacteria and Ascomycota in studied sites, respectively. Additionally, revegetation significantly increased the relative abundances of Proteobacteria, Gemmatimonadetes, Bacteroidetes and Patescibacteria, and decreased the relative abundance of Actinobacteria. Robinia pseudoacacia harbored the highest soil fungal community diversity, and bacterial Simpson index and Shannon index. Vegetation restoration with RP could clearly shifted soil communities compared to AM and PK. Along with the restoration of vegetation, the remarkable abiotic changes were the accumulation of total C, total N, total P, available P, available N and available K and the decreasing of soil pH, which were the most important factors affecting soil microbial communities. Our results addressed that Robinia pseudoacacia was the best preferable species than AM and PK in improving soil nutrients, soil community diversity and structure in Fe mining, providing a helpful guideline for selection of tree species.

Different revegetation types alter soil physical-chemical characteristics and fungal community in the Baishilazi Nature Reserve.

The effects of different revegetation types on soil physical-chemical characteristics and fungal community diversity and composition of soils sampled from five different revegetation types (JM, Juglans mandshurica; QM, Quercus mongolica; conifer-broadleaf forest (CB); LG, Larix gmelinii; PK, Pinus koraiensis) in the Baishilazi Nature Reserve were determined. Soil fungal communities were assessed employing ITS rRNA Illunima Miseq high-throughput sequencing. Responses of the soil fungi community to soil environmental factors were assessed through canonical correspondence analysis (CCA) and Pearson correlation analysis. The coniferous forests (L. gmelinii, P. koraiensis) and CB had reduced soil total carbon (C), total nitrogen (N), and available nitrogen (AN) values compared with the broadleaf forest (J. mandshurica, Q. mongolica). The average fungus diversity according to the Shannon, ACE, Chao1, and Simpson index were increased in the J. mandshurica site. Basidiomycota, Ascomycota, Zygomycota, and Rozellomycota were the dominant fungal taxa in this region. The phylum Basidiomycota was dominant in the Q. mongolica, CB, L. gmelinii, and P. koraiensis sites, while Ascomycota was the dominant phylum in the J. mandshurica site. The clear differentiation of fungal communities and the clustering in the heatmap and in non-metric multidimensional scaling plot showed that broadleaf forests, CB, and coniferous forests harbored different fungal communities. The results of the CCA showed that soil environmental factors, such as soil pH, total C, total N, AN, and available phosphorus (P) greatly influenced the fungal community structure. Based on our results, the different responses of the soil fungal communities to the different revegetation types largely dependent on different forest types and soil physicochemical characteristic in Baishilazi Nature Reserve.

Comparison of soil bacterial community and functional characteristics following afforestation in the semi-arid areas.

Changes in soil bacterial communities, which are crucial for the assessment of ecological restoration in Chinese plantations, have never been studied in the "Three North Shelterbelt" project in the semi-arid areas. We used high-throughput sequencing of the 16S rDNA gene to investigate the soil bacterial community diversity, structure, and functional characteristics in three plantation forests, including Populus × canadensis Moench (PC), Pinus sylvestris var. mongolica (PS), and Pinus tabuliformis (PT). In addition, soil environment factors were measured. There were distinct differences in soil characteristics among different plantation forests. Compared to PS and PT, PC had a higher soil pH, dissolved organic carbon (DOC), and available P, as well as a lower C/N ratio. Furthermore, afforestation with different tree species significantly altered the abundance of Proteobacteria, and Chloroflexi in the soil, and its influence on the bacterial diversity indices. The bacterial community compositions and functional groups related to C and N cycling from PS, and PT were grouped tightly, indicating that the soil bacterial phylogenetic distance of PS and PT were closer than that between PS plus PT and PC. Our results implied that the soil characteristics, as well as the diversity, compositions and functions related to C and N cycling of soil bacterial community obviously differed from the following afforestation, especially between PC and PS plus PT, which in turn enormously established the correlation between the soil microbial community characteristics and the afforestation tree species.