Bacteria, fungi, archaea, and viruses are reflective organisms that indicate soil health. Investigating the impact of crude oil pollution on the community structure and interactions among bacteria, fungi, archaea, and viruses in Calamagrostis epigejos soil can provide theoretical support for remediating crude oil pollution in Calamagrostis epigejos ecosystems. In this study, Calamagrostis epigejos was selected as the research subject and subjected to different levels of crude oil addition (0 kg/hm², 10 kg/hm², 40 kg/hm²). Metagenomic sequencing technology was employed to analyze the community structure and diversity of soil bacteria, fungi, archaea, and viruses. Additionally, molecular ecological network analysis was integrated to explore species interactions and ecosystem stability within these microbial communities. The functional profiles of soil microorganisms were elucidated based on data from the KEGG database. Results demonstrated a significant increase in petroleum hydrocarbon content, polyphenol oxidase activity, hydrogen peroxide enzyme activity, and acid phosphatase activity upon crude oil addition, while β-glucosidase content, fiber disaccharide hydrolase content, and tiller number decreased (P < 0.05). Proteobacteria and Actinobacteria were identified as dominant bacterial phyla; Ascomycota, Basidiomycota, and Mucoromycota were found to be dominant fungal phyla; Thaumarchaeota emerged as a dominant archaeal phylum; and Uroviricota represented a dominant viral phylum. The diversity of soil bacterial, fungal, archaeal, and viral communities increased with higher amounts of added crude oil. Ecological network analysis revealed a robust collaborative relationship among bacterial, fungal, archaeal, and viral community species in the control treatment (CK), while strong competitive relationships were observed among these species in the treatments with 10% (F10) and 40% (F40) crude oil concentrations. Structural equation modeling analysis indicated significant positive correlations between fungal community, viral community, enzyme activity, and plant growth; conversely, bacterial and archaeal communities showed significant negative correlations with plant growth (P < 0.05). Correlation analysis identified acid phosphatase as the primary environmental factor influencing soil microbial function. Acid phosphatase levels along with tiller number, aboveground biomass, and petroleum hydrocarbons significantly influenced the fungal community (P < 0.05), while underground biomass had a significant impact on the archaeal community (P < 0.05). Acid phosphatase levels along with cellulose-hydrolyzing enzymes, tiller number, and petroleum hydrocarbons exhibited significant effects on the viral community (P < 0.05). This study investigated variations in bacterial, fungal, archaeal, and viral communities under different crude oil concentrations as well as their driving factors, providing a theoretical foundation for evaluating Calamagrostis epigejos’ potential to remediate crude oil pollution.

Fire and mowing are crucial drivers of grass growth. However, their effects on soil properties, microbial communities, and plant productivity in dry-alkaline grasslands have not been well investigated. This study evaluated the effects of mowing (slightly and deeply) and fire on vegetation traits (Tiller number per cluster and plant height) and biomass (plant dry weight), and soil availability of N, P, and K, as well as soil microorganism abundance in a Miscanthus system. We designed one control and three experimental grass plots (slightly and deeply mowed, and burned) in 2020–2021 in the Xi’an Botanical Garden of Shaanxi Province, Xi’an, China. Tiller number, plant height per cluster, and soil N, P, and K availability during Miscanthus growth decreased significantly (p < 0.05) in all treatments compared to the control. However, this effect was much greater in the deep-mowing plot than in the other plots. After harvest, deep mowing induced the greatest effect on biomass among all treatments, as it induced a 5.2-fold decrease in dry biomass relative to the control. In addition, both fire and mowing slightly redistributed the community and diversity of the soil bacteria and fungi. This redistribution was significantly greater in the deep-mowing plot than in other plots. In particular, relative to the control, deep mowing increased the abundance of Firmicutes and especially Proteobacteria among soil bacterial communities, but significantly (p < 0.05) decreased Basidiomycota and increased Ascomycota abundance among soil fungal communities. We conclude that nutrient limitation (N, P, and K) is crucial for Miscanthus growth in both mowing and fire grasslands, whereas deep mowing can induce soil nutrient loss and microorganism redistribution, further restraining grass sustainability in dry-alkaline grasslands.

Plant restoration strategies are ubiquitously employed for the purposes of soil and water conservation and ecological improvement in forest ecosystems. Despite N and temperature being acknowledged as pivotal factors affecting plant restoration outcomes, their effects on soil fertility, microbial communities, and shrub biomass remain underexplored, particularly in the loess hilly regions of China. Here, we examined the growth patterns and nutrient acquisition abilities of three shrub species, Periploca sepium, Amorpha fruticosa, and Vitex negundo, along with the attendant alterations in soil properties and microbial community composition under controlled greenhouse conditions. Specifically, we imposed three levels of N fertilization (200, 400, and 600 kg ha⁻¹; designated as N1, N2, and N3, respectively) and temperature regimes (18–23, 25–30, and 32–37 °C; labeled T1, T2, and T3, respectively). The results indicated a significant interplay between the combination of N fertilization and temperature significantly affecting shrub growth. Optimal growth conditions, as evidenced by the highest dry biomass accumulation, were identified as N3T1 for A. fruticosa, N1T1 for P. sepium, and N2T2 for V. negundo, with these conditions differentially influencing roots, stems, and leaves. Furthermore, soil microorganisms also responded significantly to the N fertilization and temperature. However, this was largely dependent on shrub species and soil nutrients. For A. fruticosa under N3T1 conditions, Actinobacteria and Basidiomycota abundances correlated strongly with soil C, N, and P contents, while leaf N uptake significantly correlated with the structure of both bacterial and fungal communities. For P. sepium at N1T1, Acidobacteriota was dominant in response to soil N and C, while leaf C uptake and leaf and stem N uptake positively correlated with bacterial and fungal communities, respectively. For V. negundo at N2T2, Chloroflexi had the greatest abundance, responding to the greatest variation in soil N and C, while its stem N uptake was significantly related to the structure of the fungal communities. Thus, our findings underscored the intricate interplay between abiotic factors, shrub growth, soil fertility, and microbial community dynamics, providing insights into the optimization of plant restoration efforts in ecologically sensitive regions.

This study aimed to reveal the effects of crude oil addition on the characteristics of soil microbial communities and ecosystem multifunctionality in Achnatherum splendens and Pennisetum alopecuroides. Specifically, it explored how crude oil addition influences the relationship between soil nutrient regulation, microbial community characteristics, and ecosystem multifunctionality. The results indicated that as crude oil addition increased, the Shannon index and Chao1 index for soil bacteria and fungi in both Achnatherum splendens and Pennisetum alopecuroides increased. Conversely, while the Shannon index for soil archaea in both species increased, the Chao1 index decreased. The ecological network analysis indicated that a strong collaborative relationship existed between species in the soil bacterial communities of Achnatherum splendens and Pennisetum alopecuroides exposed to 10 g/kg crude oil, as well as between species in the soil fungal and archaeal communities of Achnatherum splendens exposed to 40 g/kg crude oil. A strong collaborative relationship was also observed between species in the soil fungal and archaeal communities of Pennisetum alopecuroides exposed to 10 g/kg crude oil. The bacterial and fungal communities exerted a significant direct negative regulatory effect on the soil ecosystem multifunctionality of Achnatherum splendens and Pennisetum alopecuroides, while the archaeal communities had a significant direct positive regulatory effect. Additionally, the multifunctionality index of the soil ecosystem in Achnatherum splendens and Pennisetum showed a significant decline with increasing crude oil addition. This is likely due to the higher toxicity of high-concentration crude oil, which negatively impacts the soil biological community, leading to reduced biodiversity and disruptions in nutrient cycles. This study explores the characteristics of bacterial, fungal, and archaeal communities and ecosystem multifunctionality under different levels of crude oil, which can provide theoretical support for evaluating the restoration of Achnatherum splendens and Pennisetum alopecuroides from crude oil pollution.