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The combined effects of warming and increased nitrogen (N) deposition in various ecosystems have become global issues. We used high‐throughput sequencing in an 8‐year field experiment to evaluate the impacts of the interactions between warming and nitrogen addition on soil nematode communities in a desert steppe. The soil nematode community presented with a certain degree of tolerance to warming. Warming mainly altered soil nematode diversity and community stability in deep soils whereas nitrogen addition primarily affected the nematode community in surface soils. Moreover, warming interacted with nitrogen addition exacerbated its negative effects on nematode richness and diversity. A Mantel analysis showed that soil pH was significantly negatively correlated with soil NH4+ and NO3− content. All three soil physicochemical (pH, NH4+ and NO3−) parameters were significantly correlated with desert steppe soil nematode community structure. Based on network and relative abundance analyses, we determined that Paratylenchus, Cervidellus, and Acrobeloides were the major hub soil nematode genera responding to soil warming and nitrogen addition in a desert steppe. The present study comprehensively analyzed the responses of desert steppe soil nematode communities to warming and nitrogen addition and provided an exemplar for studying the impact of environmental factors on soil nematodes communities worldwide. [ABSTRACT FROM AUTHOR]

Purpose: Nitrogen (N) deposition and warming may influence microbially mediated processes and functioning of ecosystem. Our study aimed to examine how soil bacterial and fungal community composition, diversity, and interactions respond to N deposition and warming. Materials and methods: High-throughput sequencing and bioinformatic analysis were performed to explore microbial community composition and diversity, and cohesion analysis was adopted to assess the microbial interactions after 11 consecutive years ammonium nitrate supplementation and warming in a desert steppe of Inner Mongolia, Northern China. Results: Our results demonstrated nitrogen supplementation, warming, and N supplementation plus warming affected the bacterial and fungal community structures, and the effects were soil depth-dependent. N supplementation improved the relative abundance of copiotrophic groups (Bacteroidetes and Betaproteobacteria) and restrained oligotrophic groups (Chloroflexi, Deltaproteobacteria, and Acidobacteria) at 0–2 cm depth. N supplementation plus warming significantly increased the relative abundance of Ascomycota at 2–5 cm depth. N supplementation and N supplementation plus warming significantly reduced bacterial diversity. The redundancy analysis demonstrated that pH and N availability significantly contributed to the variation in bacterial and fungal community, respectively. N supplementation and warming simplified bacterial connectivity and improved positive cohesion: negative cohesion ratio, while warming increased fungal connectivity and reduced positive cohesion: negative cohesion ratio. Conclusion: The effects of N supplementation and warming on bacterial and fungal community structure were soil depth-dependent. N supplementation and N supplementation plus warming reduced bacterial diversity. N supplementation and warming simplified bacterial interactions. The bacterial community was more sensitive to nitrogen supplementation and warming than fungal community. [ABSTRACT FROM AUTHOR]

Grazing is a key regulator of the biodiversity of the desert steppe in Inner Mongolia and has important ecological significance for the sustainable development of underground ecosystems. In a 14‐year grazing intensity experiment, we systematically explored the changes in soil nematode communities in desert steppe soils and comprehensively evaluated the optimal grazing intensity for the sustainability of the desert steppe underground ecosystem. Using high‐throughput sequencing, we analyzed the soil nematode communities and their relationships with environmental factors. The 14‐year grazing experiment revealed a significant impact on the diversity and composition of the soil nematode community in the surface layer (0–10 cm) and on the soil nematode community in the whole soil layer (0–20 cm). Based on LEfSe multilevel discriminant analysis, we found that the relative abundances of Acrobeles, Cephalobus, Filenchus, Aphelenchus, Longidorella, Amplimerlinius, Aporcelaimellus, Acrobeloides, Dorylaimellus, Hemicycliophora, Thonus, Alaimus, and Oxydirus changed significantly under different grazing treatments. Considering the number and function of soil nematode communities, long‐term light grazing was found to significantly promote an increase in soil nematode diversity and helped maintain soil nematode community stability. We determined that the most suitable grazing intensity for the sustainability of the soil underground ecosystem of the desert steppe in Inner Mongolia is light grazing (0.91 sheep hm‐2 0.5 yr‐1). We have, thus, provided a tool for determining and evaluating optimal grazing intensities for sustainable soil underground ecosystems. [ABSTRACT FROM AUTHOR]

Background: Grazing disturbance plays an important role in the desert steppe ecosystem in Inner Mongolia, China. Previous studies found that grazing affected the spatial distribution of species in a community, and showed patchiness characteristics of species under different grazing treatments. Artemisia frigida is the dominant species and semi-shrub in desert steppe, and whether grazing interference will affect the spatial distribution of A. frigida is studied. In this study, geo-statistical methods were mainly used to study the spatial distribution characteristics of A. frigida population in desert steppe of Inner Mongolia at two scales (quadrat size 2.5 m × 2.5 m, 5 m × 5 m) and four stocking rates (control, CK, 0 sheep·ha–1·month–1; light grazing, LG, 0.15 sheep·ha–1·month–1, moderate grazing, MG, 0.30 sheep·ha–1·month–1, heavy grazing, HG, 0.45 sheep·ha–1·month–1). Results: The results showed that the spatial distribution of A. frigida tended to be simplified with the increase of stocking rate, and tended to be banded with increased spatial scale. The density and height of A. frigida increased with increasing scale. With increased stocking rate, the density of A. frigida population decreased linearly, while its height decreased in a step-wise fashion. The spatial distribution of A. frigida was mainly affected by structural factors at different scales and stocking rate. The density of A. frigida was more sensitive to change in stocking rate, and the patchiness distribution of A. frigida was more obvious with increase in scale. Conclusions: Stocking rate has a strong regulatory effect on the spatial pattern of A. frigida population in the desert steppe. Heavy grazing reduced the spatial heterogeneity of A. frigida in the desert steppe. The smaller dominant populations are unfavourable for its survival in heavy grazing condition, and affects the stability and productivity of the grassland ecosystem. [ABSTRACT FROM AUTHOR]

Ecological restoration of open‐pit mine wasteland is critical to the sustainable development of the mining industry. Using high‐throughput sequencing, we analyzed soil properties and nematode community structure and function to evaluate the impact of ecological package restoration on the quality of underground ecosystem reclamation in desert steppe open‐pit mine wasteland. After 7 years of ecological package restoration at an open‐pit quarry, two management methods (annual removal of dominant plant genera and annual reseeding of missing plants) achieved the expected outcomes of the restoration project (return to the conditions of the pre‐disturbed ecosystem). Based on LEfSe multi‐level discriminant analysis and shared genera analysis, we suggest that Oxydirus, Dorylaimus, Trichotylenchus, Plectus, Scutylenchus, Paratylenchus, Tylencholaimus, and Cephalobus may be the key soil nematode genera in the damaged open‐pit quarry ecosystem. We also evaluated the soil health status of different ecological package restoration time periods (2 and 5 years) at an abandoned desert steppe open‐pit iron mine by analysis of the soil properties and nematode communities. We suggest that ecological package restoration for 5 years achieved the expected restoration outcomes in the open‐pit iron mine wasteland. Based on LEfSe analysis and shared genera analysis, we suggest that Acrobeles, Microdorylaimus, Cehalobus, Tripylina, and Ecumenicus may be the key soil nematode genera in the damaged open‐pit iron mine ecosystem. Our findings provide a reference for evaluating the reclamation effect of ecological package restoration in open‐pit mine areas. [ABSTRACT FROM AUTHOR]

Repair of damaged areas in open‐pit (opencast) coal mines has emerged as an important environmental concern. Our research investigated the mechanism by which different ecological restoration methods affected soil nematode communities in damaged areas of desert steppe coal mines. Using high‐throughput sequencing technology, nematode community composition, diversity, and function were analyzed to determine the response of nematodes to different ecological restoration methods in damaged areas of coal mines. For slope rehabilitation, vegetation blanket restoration exhibited more favorable effects than those exhibited by vegetation bag restoration and natural restoration. For rehabilitation of the platform area under the slope, the diversity of soil nematodes and the soil fauna analysis under alien soil restoration conditions were performed and exhibited similar characteristics to those of the native vegetation. Findings based on Linear discriminant analysis Effect Size (LEfSe) multi‐level discriminant analysis and determination of shared genera suggest that Paraphelenchus, Cervidellus, Panagrolaimus, Microdorylaimus, Cephalobus, and Ecumenicus may be the key genera of soil nematodes in the damaged ecosystem of open‐pit coal mines in the desert steppe. We found that reasonable water and fertilizer management in slope restoration and under‐slope platform area restoration may play a key role in the restoration of damaged ecosystems in open‐pit coal mines. We comprehensively analyzed the response of soil nematode communities and their functions to different ecological restoration methods, and provided a reference for evaluating the quality of underground ecosystem restoration of damaged areas in abandoned desert steppe open‐pit coal mines. [ABSTRACT FROM AUTHOR]

Currently, the impact of changes in precipitation and increased nitrogen(N) deposition on ecosystems has become a global problem. In this study, we conducted a 8-year field experiment to evaluate the effects of interaction between N deposition and precipitation change on soil bacterial communities in a desert steppe using high-throughput sequencing technology. The results revealed that soil bacterial communities were sensitive to precipitation addition but were highly tolerant to precipitation reduction. Reduced precipitation enhanced the competitive interactions of soil bacteria and made the ecological network more stable. Nitrogen addition weakened the effect of water addition in terms of soil bacterial diversity and community stability, and did not have an interactive influence. Moreover, decreased precipitation and increased N deposition did not have a superimposed effect on soil bacterial communities in the desert steppe. Soil pH, moisture content, and NH4+-N and total carbon were significantly related to the structure of bacterial communities in the desert steppe. Based on network analysis and relative abundance, we identified Actinobacteria, Proteobacteria, Acidobacteria and Cyanobacteria members as the most important keystone bacteria that responded to precipitation changes and N deposition in the soil of the desert steppe. In summary, we comprehensively analyzed the responses of the soil bacterial community to precipitation changes and N deposition in a desert steppe, which provides a model for studying the effects of ecological factors on bacterial communities worldwide. [ABSTRACT FROM AUTHOR]

Purpose: Global warming and drying are important environmental issues. Our study aimed to investigate how warming and precipitation changes affect soil nematode communities in an Inner Mongolian desert steppe for 10 years. Materials and methods: Soil nematodes were extracted by the Baermann funnel method. Changes in the nematode communities under artificial warming and precipitation conditions were assayed by analyzing their abundance and ecological indices. Results and discussion: Soil nematode abundance decreased significantly by 37.47% under artificial warming; however, there was no significant effect of warming on the nematode community diversity. As for precipitation experiment, the decreased precipitation eliminated some of non-dominant nematode genera, such as Pratylenchus, Helicotylenchus, and Aphelenchus. It caused not only a significant decrease (37.65%) in soil nematode abundance but also a more structured food web and shorter food chain. However, nematode faunal analysis indicated that the soil nematode community was more resistant to drought. Both soil nematode abundance and community diversity increased significantly as increase of precipitation. In particular, the abundance of plant parasitic nematodes increased by 46.69%, which may due to the increase in total nitrogen content in soil. Nematode faunal analysis showed that increased precipitation improved soil environment for the nematodes, and increased food web connectivity and food chain length. However, bacterivorous nematode abundance decreased by 74.39%, and the decomposition pathway of the nematode community had switched from the bacterial channel to the fungal channel. Conclusions: In the Inner Mongolian steppe, both climate drying and warming had negative impacts on soil nematode abundance; however, only drying affected nematode community diversity and food web structure and slowly changed nematode ecological functions. Increased precipitation may aid soil nematode community recovery. [ABSTRACT FROM AUTHOR]