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Aims This study aimed to determine the responses of soil bacteria and fungi to plant species diversity and plant family composition (PFC) following secondary succession on former farmland (FL). Methods Illumina sequencing of 16S rRNA and ITS genes was used to determine soil microbial communities along a chronosequence of FL left abandoned for 0, 10, 20, 30, 40, and 50 years on the Loess Plateau. Soil properties, plant diversity, and PFC were also investigated. Results Fungal communities were dominated by Ascomycota and Basidiomycota . Fungal diversity and Ascomycota abundance increased with time, while Basidiomycota abundance decreased. The fungal diversity and dominant phyla were related to the increasing levels of plant species diversity and evenness with succession. Bacterial diversity first increased and then decreased as succession proceeded, peaking at 30 years. Bacterial communities transitioned from Actinobacteria to Proteobacteria dominance during the first 30 years, after which Actinobacteria was dominant. Plant family composition exerted indirect effects on the diversity and dominant phyla of bacterial communities, mainly through direct effects on soil organic carbon and total nitrogen content. Bacterial diversity and Proteobacteria abundance were higher at Leguminosae- and Gramineae-dominant succession stages, but lower in Compositae-dominant plots; Actinobacteria showed the opposite result. Conclusions Plant species diversity and evenness might be the key drivers for shaping fungal communities, but bacteria are influenced more by changes in PFC and abiotic soil nutrient levels during succession.

AimsWe explored the trends in soil fungal and bacterial patterns and their responses to plant and soil characteristics with increasing site age in abandoned farmland in karst areas.MethodsIllumina sequencing of 16S rRNA and ITS genes was used to characterize the soil bacterial and fungal diversities in farmland, farmland abandoned for 3, 6, 20, and 40 years, and old-growth forests in Southwest China. Plant diversity, community-weighted mean (CWM) leaf and branch traits, soil physical and chemical properties and metal element concentrations were also investigated.ResultsBacterial diversity decreased slightly with increasing site age, while fungal diversity first increased and then decreased. Ascomycota was the dominant fungal phylum, and its abundance decreased significantly, from 83.21% in farmland to 49.66% in old-growth forests, while that of Basidiomycota increased significantly from 4.52 to 35.43%. The soil bacterial community was dominated by Proteobacteria, Actinobacteria, Acidobacteria, and Chloroflexi. The fungal and bacterial diversities were mainly affected by soil properties. At the older sites, high levels of soil nitrate nitrogen (N), ammonium-N, total N, soil organic carbon, calcium, and magnesium and relatively low levels of soil potassium and available phosphorus (P) resulted in decreased bacterial diversity. Fungal diversity was positively affected by soil total P and pH and negatively affected by soil iron and copper. The bacterial and fungal compositions were jointly affected by soil properties and CWM leaf and branch traits.ConclusionsOur findings indicate that soil bacterial and fungal diversities and compositions changed significantly during secondary succession in karst areas. Microbial diversity was determined by soil properties, and compositions were jointly driven by plant and soil properties.

Soil microorganisms play an important role in the circulation of materials and nutrients between plants and soil ecosystems, but the drivers of microbial community composition and diversity remain uncertain in different vegetation restoration patterns. We studied soil physicochemical properties (i.e., soil moisture, bulk density, pH, soil nutrients, available nutrients), plant characteristics (i.e., Shannon index [HPlant ] and Richness index [SPlant ], litter biomass [LB], and fine root biomass [FRB]), and microbial variables (biomass, enzyme activity, diversity, and composition of bacterial and fungal communities) in different plant succession patterns (Robinia pseudoacacia [MF], Caragana korshinskii [SF], and grassland [GL]) on the Loess Plateau. The herb communities, soil microbial biomass, and enzyme activities were strongly affected by vegetation restoration, and soil bacterial and fungal communities were significantly different from each other at the sites. Correlation analysis showed that LB and FRB were significantly positively correlated with the Chao index of soil bacteria, soil microbial biomass, enzyme activities, Proteobacteria, Zygomycota, and Cercozoa, while negatively correlated with Actinobacteria and Basidiomycota. In addition, soil water content (SW), pH, and nutrients have important effects on the bacterial and fungal diversities, as well as Acidobacteria, Proteobacteria, Actinobacteria, Nitrospirae, Zygomycota, and microbial biomass. Furthermore, plant characteristics and soil properties modulated the composition and diversity of soil microorganisms, respectively. Overall, the relative contribution of vegetation and soil to the diversity and composition of soil bacterial and fungal communities illustrated that plant characteristics and soil properties may synergistically modulate soil microbial communities, and the composition and diversity of soil bacterial and fungal communities mainly depend on plant biomass and soil nutrients.

Despite the known influence of continuous cropping on soil microorganisms, little is known about the associated difference in the effects of continuous cropping on the community compositions of soil bacteria and fungi. Here, we assessed soil physicochemical property, as well as bacterial and fungal compositions across different years (Uncropped control, 1, 6, 11, 16, and 21 years) and in the watermelon system of a gravel mulch field in the Loess Plateau of China. Our results showed that long-term continuous cropping led to substantial shifts in soil bacterial and fungal compositions. The relative abundances of dominant bacterial and fungal genera (average relative abundance > 1.0%) significantly varied among different continuous cropping years ( P  < 0.05). Structural equation models demonstrated that continuous cropping alter soil bacterial and fungal compositions mainly by causing substantial variations in soil attributes. Variations in soil pH, nutrient, salinity, and moisture content jointly explained 73% and 64% of the variation in soil bacterial and fungal compositions, respectively. Variations in soil moisture content and pH caused by continuous cropping drove the shifts in soil bacterial and fungal compositions, respectively (Mantel R  = 0.74 and 0.54, P  < 0.01). Furthermore, the variation in soil bacterial and fungal composition showed significant correlation with watermelon yield reduction ( P  < 0.01). Together, long-term continuous cropping can alter soil microbial composition, and thereby influencing watermelon yield. Our findings are useful for alleviating continuous cropping obstacles and guiding agricultural production.

Aims This study focuses on the changes and associations between soil dissolved organic matter (DOM) and microbial communities during the vegetation restoration process (abandoned farmland, 5, 15, 20, and 40 years of vegetation restoration) in grasslands on the Loess Plateau of China. Methods High-throughput sequencing was used to determine microbial community and composition, and Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) was used to obtain specific information on DOM molecules, explored the specific relationship between DOM chemical diversity and microbial communities during vegetation restoration. Results Vegetation restoration promotes increased diversity and complexity of soil DOM molecules. During vegetation restoration, the content of recalcitrant DOM components (lignin/carboxyl-rich alicyclic molecules (CRAM)-like structures, aromatic structures, tannins) increased, but the content of labile DOM (aliphatic/proteins, carbohydrates, lipids) decreased. The alpha diversity of microbial communities varied significantly with niche width. Stochastic processes shaped the bacterial community, while deterministic processes dominated the fungal community. Chloroflexi , Actinobacteria , and Ascomycota were negatively correlated with most lignin/CRAM-like structures and tannins, whereas Acidobacteria and Proteobacteria were positively correlated. Conclusions Vegetation restoration promotes an increase in recalcitrant DOM content (difficult for microorganisms to degrade) and facilitates soil carbon sequestration. Microorganisms are able to consume and form DOM molecules and play a huge role in the transformation of soil DOM. This study increases the understanding of the potential link between microbes and DOM fate during grassland vegetation restoration, and emphasizes the necessity of “Grain-for-Green” project to reduce carbon emissions in the context of global climate change.

Loam examples were gathered through the 2020-2021 rising periods, and the following measurements were made: Viable bacterial count by reducing root colonization. The outcomes of reviewing the impact of the fungicide Benomyl on development and viable microflora count revealed that the highest microbial count was in Al-Madaein 80 ×103 CFU/mL was recorded ., and the lowest count was 60 ×103 CFU/mL for the Aushtar area, The microbial viable count values for the affected microorganisms with Benomyl were decrease to 27×103 and 65 × 103 CFU/mL respectively. Those consequences specify that Benomyl has a robust choosiness contrary to microflora, especially when compared to the benomyl effect as folded dose, the microflora l count decreases to 25 ×103 CFU /mL in the Aushtar area and increases to 60 ×103 CFU/mL in Al-Madaein area. Whereas the study estimated the level of eight elements in soil (Mn, Fe, Cu, Zn, NO3, P, K, and NH4) cultured with Cyperus rotundus L. Which mentioned the effect of benomyl on these levels after three days of treatment. Mn concentration ranged between 5.96 to 9.11 ppm, while after fungicide benomyl, it decreased to 5.63 -6.53 ppm similar results were observed for other elements. The highest affected element was Mn in the Aushtar area. Those consequences designate that Benomyl has a stout fussiness in contrast to soil nutrients. The greatness of benomyl impacts on loam ingredients and procedures were minor, qualified to impact on mycorrhizal root foundation (reduction through benomyl).

Changes in soil physicochemical properties and bacterial community composition were investigated six years after biochar amendment at 0%, 4%, 8% and 12% (w/w), which were coded as C0, C1, C2 and C3, respectively. Results showed that some soil characteristics were sustainable, as they were still affected by biochar addition after six years. Compared to the control, biochar-treated soils had higher pH, total carbon (TC), C/N, total nitrogen (TN), available phosphorus (AP) and available potassium (AK). Soil pH, C/N and the content of TC, TN and AK all increased along with the increase of biochar dosage. The results of Illumina MiSeq sequencing demonstrated that biochar enhanced soil bacteria diversity and modified the community composition over time. The relative abundance of Nitrospirae and Verrucomicrobia phylum increased but that of Acidobacteria phylum decreased significantly in biochar amended soils. The addition of biochar also enriched some bacterial genera, such as uncultured Nitrosomonadace, uncultured Gemmatimonadac, uncultured Nitrospiraceae and Magnetovibrio. In particular, the relative abundance of uncultured Nitrospiraceae was enhanced by 16.9%, 42.8% and 73.6% in C1, C2 and C3, respectively, compared to C0. Biochar has a potential role in enhancing the abundance of bacteria involved in N cycling. Soil pH, TC, TN, TK and AK, were closely related to alterations in the composition of the soil bacterial community. Meanwhile, these soil properties were significantly influenced by biochar amendment, which indicates that biochar affected the soil microbial community indirectly by altering the soil characteristics in the long term.

ABSTRACT Fire can impact terrestrial ecosystems by changing abiotic and biotic conditions. Short fire intervals maintain grasslands and communities adapted to frequent, low-severity fires. Shrub encroachment that follows longer fire intervals accumulates fuel and can increase fire severity. This patchily distributed biomass creates mosaics of burn severities in the landscape—pyrodiversity. Afforded by a scheduled burn of a watershed protected from fires for 27 years, we investigated effects of woody encroachment and burn severity on soil chemistry and soil-inhabiting bacteria and fungi. We compared soils before and after fire within the fire-protected, shrub-encroached watershed and soils in an adjacent, annually burned and non-encroached watershed. Organic matter and nutrients accumulated in the fire-protected watershed but responded less to woody encroachment within the encroached watershed. Bioavailable nitrogen and phosphorus and fungal and bacterial communities responded to high-severity burn regardless of encroachment. Low-severity fire effects on soil nutrients differed, increased bacterial but decreased fungal diversity and effects of woody encroachment within the encroached watershed were minimal. High-severity burns in the fire-protected watershed led to a novel soil system state distinct from non-encroached and encroached soil systems. We conclude that severe fires may open grassland restoration opportunities to manipulate soil chemistry and microbial communities in shrub-encroached habitats. High-severity burns result in a novel soil microbiome regardless of whether applied to grass-dominated or woody-plant invaded patches in a fire-protected, encroached prairie watershed.

Soil microorganisms play crucial roles in maintaining material circulation and energy flow in desert ecosystems. However, the structure and function of soil microorganisms in different forestlands are currently unclear, restricting the use of sand-fixing plants and the understanding of forest ecosystem functions. In this study, Artemisia ordosica, Caragana korshinskii, and Salix psammophila, three types of sand-fixing forests widely distributed in the Mu Us Sandy Land, were used to explore the effects of sand-fixing forests on soil physicochemical properties, soil enzyme activity, soil microbial biomass, microbial community structure, and inter-microbial species relationships. Soils of forestlands showed higher soil organic carbon (SOC), total phosphorus (TP), and total nitrogen (TN) contents than bare sandy land. The SOC in bare sandy soil was only 0.84 g kg−1, while it remained 1.55–3.46 g kg−1 in forestland soils. The TN in bare sandy land soil was 0.07 g kg−1, which was significantly lower than that in forestland soils (0.35–0.51 g kg−1). The TP in bare sandy soil was 0.18 g kg−1, significantly lower than that in forestland soils (0.46–0.69 g kg−1). Afforestation of bare sandy land improved soil microbial carbon and nitrogen contents and increased microbial enzyme activities of acid phosphatase and N-acetyl-β-D-glucosaminidase. Significant differences were observed between the three forestlands and bare sandy land in terms of soil microorganisms and community composition. With the establishment of a sand-fixing forest, the alpha diversity of soil bacteria significantly improved, whereas that of soil fungi remained stable. The bacterial community comprised 33 phyla, 106 classes, 273 orders, 453 families, and 842 genera. While five fungal phyla were detected by OTUs at a similarity of 97%, bacterial and fungal community structures were affected by the organic carbon content, sand particle content, soil pH, total nitrogen, and total phosphorus contents of soils. This study is helpful for vegetation construction and protection on sandy lands from the perspective of plant-microbe interactions.

This research aimed to study changes in the diversity of the soil bacterial community in a jujube forest with different years of abandonment. To this end, we took the mountain jujube forest with different abandoned years (1 a, 3 a, 6a and 20 a) in the Qijiashan jujube experimental demonstration base in Yanchuan County as the research object; we used Illumina Miseq high-throughput sequencing technology to analyze the changes in the soil bacterial community structure and reveal the key environmental drivers of bacterial community variation in the abandoned jujube forest in the study area. The results showed the following findings: (1) Phylum Actinomycetota (34%), Proteobacteria (29%), and Acidobacteriota (13%) were the dominant phyla of the soil bacterial community in the abandoned jujube forest. (2) Abandonment altered the composition of soil bacteria at the OTU level in jujube plantations. (3) There are differences in the soil bacterial community structure across different periods of abandonment in the jujube forest. (4) Soil water content is the main factor affecting the bacterial community structure of the abandoned jujube forest. There are differences in the soil water content of abandoned woodlands, which affects the community structure of soil microorganisms.