scholarly journals Effects of Simulated Nitrogen Deposition on the Bacterial Community of Urban Green Spaces

2021 ◽  
Vol 11 (3) ◽  
pp. 918
Author(s):  
Lingzi Mo ◽  
Augusto Zanella ◽  
Xiaohua Chen ◽  
Bin Peng ◽  
Jiahui Lin ◽  
...  

Continuing nitrogen (N) deposition has a wide-ranging impact on terrestrial ecosystems. To test the hypothesis that, under N deposition, bacterial communities could suffer a negative impact, and in a relatively short timeframe, an experiment was carried out for a year in an urban area featuring a cover of Bermuda grass (Cynodon dactylon) and simulating environmental N deposition. NH4NO3 was added as external N source, with four dosages (N0 = 0 kg N ha−2 y−1, N1 = 50 kg N ha−2 y−1, N2 = 100 kg N ha−2 y−1, N3 = 150 kg N ha−2 y−1). We analyzed the bacterial community composition after soil DNA extraction through the pyrosequencing of the 16S rRNA gene amplicons. N deposition resulted in soil bacterial community changes at a clear dosage-dependent rate. Soil bacterial diversity and evenness showed a clear trend of time-dependent decline under repeated N application. Ammonium nitrogen enrichment, either directly or in relation to pH decrease, resulted in the main environmental factor related to the shift of taxa proportions within the urban green space soil bacterial community and qualified as a putative important driver of bacterial diversity abatement. Such an impact on soil life induced by N deposition may pose a serious threat to urban soil ecosystem stability and surrounding areas.

Author(s):  
Yinhong Hu ◽  
Weiwei Yu ◽  
Bowen Cui ◽  
Yuanyuan Chen ◽  
Hua Zheng ◽  
...  

Human disturbance and vegetation are known to affect soil microorganisms. However, the interacting effects of pavement and plant species on soil bacterial communities have received far less attention. In this study, we collected soil samples from pine (Pinus tabuliformis Carr.), ash (Fraxinus chinensis), and maple (Acer truncatum Bunge) stands that grew in impervious, pervious, and no pavement blocks to investigate the way pavement, tree species, and their interaction influence soil bacterial communities by modifying soil physicochemical properties. Soil bacterial community composition and diversity were evaluated by bacterial 16S amplicon sequencing. The results demonstrated that soil bacterial community composition and diversity did differ significantly across pavements, but not with tree species. The difference in soil bacterial community composition across pavements was greater in pine stands than ash and maple stands. Soil bacterial diversity and richness indices decreased beneath impervious pavement in pine stands, and only bacterial richness indices decreased markedly in ash stands, but neither showed a significant difference across pavements in maple stands. In addition, bacterial diversity did not differ dramatically between pervious pavement and no pavement soil. Taken together, these results suggest that pavement overwhelmed the effects of tree species on soil bacterial communities, and had a greater effect on soil bacterial communities in pine stands, followed by ash and maple stands. This study highlights the importance of anthropogenic disturbance, such as pavement, which affects soil microbial communities.


1999 ◽  
Vol 65 (8) ◽  
pp. 3622-3626 ◽  
Author(s):  
Klaus Nüsslein ◽  
James M. Tiedje

ABSTRACT The change in vegetative cover of a Hawaiian soil from forest to pasture led to significant changes in the composition of the soil bacterial community. DNAs were extracted from both soil habitats and compared for the abundance of guanine-plus-cytosine (G+C) content, by analysis of abundance of phylotypes of small-subunit ribosomal DNA (SSU rDNA) amplified from fractions with 63 and 35% G+C contents, and by phylogenetic analysis of the dominant rDNA clones in the 63% G+C content fraction. All three methods showed differences between the forest and pasture habitats, providing evidence that vegetation had a strong influence on microbial community composition at three levels of taxon resolution. The forest soil DNA had a peak in G+C content of 61%, while the DNA of the pasture soil had a peak in G+C content of 67%. None of the dominant phylotypes found in the forest soil were detected in the pasture soil. For the 63% G+C fraction SSU rDNA sequence analysis of the three most dominant members revealed that their phyla changed from Fibrobacter andSyntrophomonas assemblages in the forest soil toBurkholderia and Rhizobium–Agrobacteriumassemblages in the pasture soil.


2021 ◽  
Author(s):  
Jun Li ◽  
Xiaoyu Cheng ◽  
Wei Chen ◽  
Hanjie Zhang ◽  
Tianlang Chen ◽  
...  

Abstract Continuous cropping of cut chrysanthemum causes soil degradation and chrysanthemum quality decline, but the biotic and abiotic mechanisms behind it remain unclear. This impedes our ability to assess the true effects of continuous cropping on agricultural soil functions and our ability to repair impaired soils. Here we examined the impact of different replanting years on microbial communities and enzyme activities in rhizosphere soil of cut chrysanthemum (Chrysanthemum morifolium). Our results showed that soil total nitrogen (TN) and organic carbon (SOC) contents were significantly lower in the soil with 12 years of continuous cropping (Y12) than that in the soil with 1 year of cropping (Y1). Compared with Y1, Y12 treatment decreased alkaline phosphatase and β -glucosidase by 12.1 and 24.4%, but increased the activities of soil urease and catalase by 98.2 and 34.8%, respectively. Soil bacterial populations in Y6 (continuous cropping for 6 years) and Y12 treatments decreased by 52.3 and 87.5% compared with that in Y1 treatment. Moreover, the bacterial α-diversity (Shannon index) significantly decreased by 37.3 and 57.6% over 6 and 12 years of continuous cropping, respectively. Long-term monoculture cropping shifted the bacterial community composition, with decreased abundances of dominant phyla such as Proteobacteria and Acidobacteria, but with an increase in the relative abundances of Actinobacteria and Chloroflexi, and Gemmatimonadetes. Moreover, Y6 and Y12 treatments harbored less microbial network complexity, lower bacterial taxa, and fewer linkages among bacterial taxa, relative to Y1. Soil pH, SOC, and TN were the main edaphic factors affecting soil bacterial community compositions and diversity. Overall, our results demonstrate that continuous cropping has a significant negative impact on soil microbial diversity and complexity.


2010 ◽  
pp. 63-67
Author(s):  
Leandro Nascimento Lemos ◽  
Afnan Khalil Ahmad Suleiman ◽  
Antônio Batista Pereira ◽  
Luiz Fernando Wurdig Roesch

Author(s):  
Shu-chun Tseng ◽  
Chih-ming Liang ◽  
Taipau Chia ◽  
Shan-shin Ton

The structural changes of microorganisms in soil are the focus of soil indicators research. The purpose of this study was to investigate the changes in the composition of the soil bacterial community in heavy metal-contaminated soil. A total of six soil samples (two sampling times) were collected from contaminated farmland at three different depths (surface, middle, and deep layer). The pH value was measured. The concentrations of heavy metals (Cr, Ni, Cu, Zn, Cd, and Pb) and the soil bacterial community were analyzed using ICP-OES and 16S rRNA gene sequencing. The results of the two samplings showed that the pH value in the deep layer decreased from 6.88 to 6.23, and the concentrations of Cu, Zn, Cd, and Pb, with a smaller ion radius, increased by 16–28%, and Shannon, Chao1 increased by ~13%. The bacteria community composition at the three depths changed, but Proteobacteria, Acidobacteria, and Actinobacteria were the dominant phyla. In the copper and zinc tolerance test, the isolated bacterium that was able to tolerate copper and zinc was Bacillus sp. We found that, the longer the heavy metal pollution was of concern, the higher the tolerance. These results can be used as references for the microbial remediation of heavy metal-contaminated farmland.


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