In order to understand the effects of nitrogen deposition on soil fungal diversity, a study was conducted with a Deyeuxia augustifolia wetland in the Sanjiang Plain, China, using an experimental setup simulating nitrogen deposition at different loads over a five-year period. Three conditions were investigated: N1 (no artificial deposits, control), N2 with low-level nitrogen deposition (4 g N·hm -2 a -1) and N3 with high-level nitrogen deposition (8 g N·hm -2 a -1). At the end of the experiment the soil physiochemical characteristics were determined and high-throughput sequencing was employed to monitor the soil fungal diversity. The addition of exogenous nitrogen to the soils changed the physicochemical properties of the soils and affected the fungal community composition and the relative abundance of species: low doses increased the diversity while high doses reduced the fungal diversity. In each of the three types of nitrogen-amended soils, the most predominant phyla were Ascomycota followed by Basidiomycota. The abundance of Basidiomycota decreased with nitrogen deposition, while Ascomycota changed in the opposite direction. A heatmap tree based on ITS rDNA sequences illustrated how different fungal communities responded differently to nitrogen deposition. The findings in the present study provide fundamental data and theoretical insights that can be employed to predict the effects of atmospheric nitrogen deposition on wetland soil fungi and wetland ecosystems in Sanjiang Plain.

Different perturbation regimes,including disturbance caused by cultivation or the process of natural restoration can have significant effects on the soil acidobacterial community in wetland. The relationship between the community composition and diversity of acidobacteria and perturbation in wetland to quantify the extent of such disturbance related changes in northeast China. We assessed the diversity of acidobacterial communities in nine samples of wetland soil collected from pristine marsh, neighboring cropland and a restoration forest land. High-throughput sequencing of a acidobacteria-specific genomic sequence the internal transcribed spacer (16S rRNA) region was used to identify acidobacterial taxa. We obtained 1, 523, 313 sequences that represented 7881 acidobacterial operational taxonomic units across the three types of sampling sites. Of these, 2847OTUs occurred at all three site types, 814 were shared between farmland and pristine wetland, 206 were shared between forestland and pristine wetland 1459 were shared between farmland and forestland. All sites also hosted unique acidobacterial OTUs with 639 OTUs exclusive to farmland 1616 exclusive to pristine wetland and 300 exclusive to forestland. Sequences were affiliated to 25 acidobacterial subgroups throughout the dataset. Sequence abundance showed that members of Acidobacteria_Gp1, Acidobacteria_Gp3, Acidobacteria_Gp7, Acidobacteria_Gp6, Acidobacteria_Gp2, Acidobacteria_Gp4, Acidobacteria_Gp13 (relative abundance>1%), which represented an overwhelming proportion of the soil acidobacterial communities and another 18 subgroups with an average relative abundance were＜1%. The dominant subgroups that showed the greatest variation among habitat types. The soil bacterial community diversity decreased from a maximum in farmland, through the wetland, to a minimum in forestland. Canonical correlation analyses demonstrated that land use patterns changing, significantly altered the bacterial community composition of soil. The α-diversity of the soil acidobacterial community was most affected by soil physical and chemical properties, such as pH, soil organic carbon (SOC), total nitrogen (TN), available nitrogen (AN) and available phosphorus (AP). Meanwhile, the soil acidobacterial community composition was significantly affected by pH available phosphorus, nitrogen and organic carbon. Overall, the results from our study showed that the acidobacterial community composition of wetland were affected by SOC, TN, TP and AN. In addition, our results also indicate that cultivation and natural restoration influenced the acidobacterial community structure and diversity. Cultivation can significantly enhance the acidobacterial diversity; however, once the composition of the wetland bacterial community has been altered by cultivated disturbance, it might be difficult to restore to its original state. These findings highlight the importance of effectively managing the soil acidobacterial community to maintain a naturally functioning soil ecosystem.

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