Cessation of grazing causes biodiversity loss and homogenization of soil food webs

There is widespread concern that cessation of grazing in historically grazed ecosystems is causing biotic homogenization and biodiversity loss. Here, we used 12 montane grassland sites along an 800-km north-south gradient across the United Kingdom, to test whether cessation of grazing affects local ɑ- and β-diversity of belowground food webs. We show that cessation of grazing leads to strongly decreased ɑ-diversity of both soil microbial and faunal diversity. In contrast, the β-diversity varied between groups of soil organisms. While soil microbial communities exhibited increased homogenization after cessation of grazing, we observed decreased homogenization for soil fauna after cessation of grazing. Overall, our results indicate that grazer exclusion from historically grazed montane grasslands has far-ranging consequences for the diversity and composition of belowground food webs, and underscore the importance of grazers for maintaining the diversity of belowground communities, which play a central role in ecosystem functioning.

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Microplastics negatively affect soil fauna but stimulate microbial activity: insights from a field-based microplastic addition experiment

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2020.1268 ◽

2020 ◽

Vol 287 (1934) ◽

pp. 20201268 ◽

Cited By ~ 1

Author(s):

Dunmei Lin ◽

Guangrong Yang ◽

Pengpeng Dou ◽

Shenhua Qian ◽

Liang Zhao ◽

...

Keyword(s):

Food Webs ◽

Structural Equation ◽

Soil Fauna ◽

Soil Microbial Communities ◽

Ecological Impacts ◽

Trophic Levels ◽

Soil Community ◽

Soil Microbial ◽

Soil Food Webs ◽

Manipulation Experiment

Microplastics are recognized as an emerging contaminant worldwide. Although microplastics have been shown to strongly affect organisms in aquatic environments, less is known about whether and how microplastics can affect different taxa within a soil community, and it is unclear whether these effects can cascade through soil food webs. By conducting a microplastic manipulation experiment, i.e. adding low-density polyethylene fragments in the field, we found that microplastic addition significantly affected the composition and abundance of microarthropod and nematode communities. Contrary to soil fauna, we found only small effects of microplastics on the biomass and structure of soil microbial communities. Nevertheless, structural equation modelling revealed that the effects of microplastics strongly cascade through the soil food webs, leading to the modification of microbial functioning with further potential consequences on soil carbon and nutrient cycling. Our results highlight that taking into account the effects of microplastics at different trophic levels is important to elucidate the mechanisms underlying the ecological impacts of microplastic pollution on soil functioning.

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Tracing boundaries in Eastern Antarctica: Multi-scale drivers of soil microbial communities across the hyperarid Vestfold Hills

10.1101/2021.09.22.461446 ◽

2021 ◽

Author(s):

Eden Zhang ◽

Paul Czechowski ◽

Aleks Terauds ◽

Sin Yin Wong ◽

Devan S. Chelliah ◽

...

Keyword(s):

Rank Order ◽

Soil Microbial Communities ◽

Biodiversity Loss ◽

Ecosystem Dynamics ◽

Soil Microbiome ◽

Successful Implementation ◽

Predictive Capacity ◽

Forest Modelling ◽

Soil Microbial ◽

Vestfold Hills

AbstractMicroorganisms are key to sustaining core ecosystem processes across terrestrial Antarctica but they are rarely considered in conservation frameworks. Whilst greater advocacy has been made towards the inclusion of microbial data in this context, there is still a need for better tools to quantify multispecies responses to environmental change. Here, we extend the scope of Gradient Forest modelling beyond macroorganisms and small datasets to the comprehensive polar soil microbiome encompassing >17, 000 sequence variants for bacteria, micro-eukarya and archaea throughout the hyperarid Vestfold Hills of Eastern Antarctica. Quantification of microbial diversity against 79 physiochemical variables revealed that whilst rank-order importance differed, predictors were broadly consistent between domains, with greatest sharing occurring between bacteria and micro-eukarya. Moisture was identified as the most robust predictor for shaping the regional soil microbiome, with highest compositional turnover or “splits” occurring within the 10 – 12 % moisture content range. Often the most responsive taxa were rarer lineages of bacteria and micro-eukarya with phototrophic and nutrient-cycling capacities such as Cyanobacteria (up to 61.81 % predictive capacity), Chlorophyta (62.17 %) and Ochrophyta (57.81 %). These taxa groups are thus at greater risk of biodiversity loss or gain to projected climate trajectories, which will inevitably disturb current ecosystem dynamics. Better understanding of these threshold tipping points will positively aid conservation efforts across Eastern Antarctica. Furthermore, the successful implementation of an improved Gradient Forest model also presents an exciting opportunity to broaden its use on microbial systems globally.

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Soil Bacterial and Fungal Composition and Diversity Responses to Seasonal Deer Grazing in a Subalpine Meadow

Diversity ◽

10.3390/d13020084 ◽

2021 ◽

Vol 13 (2) ◽

pp. 84

Author(s):

Andéole Niyongabo Turatsinze ◽

Baotian Kang ◽

Tianqi Zhu ◽

Fujiang Hou ◽

Saman Bowatte

Keyword(s):

Relative Abundance ◽

Soil Microbial Communities ◽

Gansu Province ◽

Total Carbon ◽

Mountain Range ◽

Microbial Composition ◽

Soil Microbial ◽

Β Diversity ◽

Α Diversity ◽

Soil Bacterial

Soil microbial composition and diversity are widely recognized for their role in ecological functioning. This study examined the differences of soil microbial communities between two seasonally grazed grasslands. The study area was in the Gansu red deer farm located on the Qilian Mountain range in the Gansu province of northwestern China. This farm adopted a seasonal rotation grazing system whereby grasslands at higher altitudes are grazed in summer (SG), whilst grasslands at lower altitudes are grazed in winter (WG). The soil bacterial and fungal communities were examined by Illumina MiSeq sequencing. We found that soil water content (SWC), organic carbon (OC), total carbon (TC), and total nitrogen (TN) were significantly higher, whereas the C/N ratio was significantly lower in SG than WG pastures. The α-diversity of bacteria was greater than that of fungi in both pastures, while both bacterial and fungal α-diversity were not significantly different between the pastures. The bacterial β-diversity was significantly different between the pastures, but fungal β-diversity was not. The bacterial phylum Actinobacteria and fungal phylum Ascomycota were dominant in both pastures. The relative abundance of Actinobacteria in soil was significantly higher in WG pastures, whereas the relative abundance of Proteobacteria in soil was significantly higher in SG pastures. Significant correlations between bacterial and fungal phyla and soil properties were observed, but this varied between the two grasslands. This study showed that distinct microbial community structures developed in two pastures within the same geographic location that were grazed in different seasons.

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The soil microbial food web revisited: Predatory myxobacteria as keystone taxa?

The ISME Journal ◽

10.1038/s41396-021-00958-2 ◽

2021 ◽

Author(s):

Sebastian Petters ◽

Verena Groß ◽

Andrea Söllinger ◽

Michelle Pichler ◽

Anne Reinhard ◽

...

Keyword(s):

Food Web ◽

Food Webs ◽

Microbial Food Web ◽

Organic Soils ◽

Ssu Rrna ◽

Soil Microbial ◽

Soil Food Webs ◽

Community Profiling ◽

Predatory Bacteria ◽

Mineral Soils

AbstractTrophic interactions are crucial for carbon cycling in food webs. Traditionally, eukaryotic micropredators are considered the major micropredators of bacteria in soils, although bacteria like myxobacteria and Bdellovibrio are also known bacterivores. Until recently, it was impossible to assess the abundance of prokaryotes and eukaryotes in soil food webs simultaneously. Using metatranscriptomic three-domain community profiling we identified pro- and eukaryotic micropredators in 11 European mineral and organic soils from different climes. Myxobacteria comprised 1.5–9.7% of all obtained SSU rRNA transcripts and more than 60% of all identified potential bacterivores in most soils. The name-giving and well-characterized predatory bacteria affiliated with the Myxococcaceae were barely present, while Haliangiaceae and Polyangiaceae dominated. In predation assays, representatives of the latter showed prey spectra as broad as the Myxococcaceae. 18S rRNA transcripts from eukaryotic micropredators, like amoeba and nematodes, were generally less abundant than myxobacterial 16S rRNA transcripts, especially in mineral soils. Although SSU rRNA does not directly reflect organismic abundance, our findings indicate that myxobacteria could be keystone taxa in the soil microbial food web, with potential impact on prokaryotic community composition. Further, they suggest an overlooked, yet ecologically relevant food web module, independent of eukaryotic micropredators and subject to separate environmental and evolutionary pressures.

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Relative Importance of Deterministic and Stochastic Processes on Soil Microbial Community Assembly in Temperate Grasslands

Microorganisms ◽

10.3390/microorganisms9091929 ◽

2021 ◽

Vol 9 (9) ◽

pp. 1929

Author(s):

Nana Liu ◽

Huifeng Hu ◽

Wenhong Ma ◽

Ye Deng ◽

Qinggang Wang ◽

...

Keyword(s):

Stochastic Processes ◽

Soil Microbes ◽

Explanatory Power ◽

Soil Microbial Communities ◽

Northern China ◽

Temperate Grasslands ◽

Soil Layers ◽

Soil Microbial ◽

Β Diversity ◽

Deterministic Processes

Changes in species composition across communities, i.e., β-diversity, is a central focus of ecology. Compared to macroorganisms, the β-diversity of soil microbes and its drivers are less studied. Whether the determinants of soil microbial β-diversity are consistent between soil depths and between abundant and rare microorganisms remains controversial. Here, using the 16S-rRNA of soil bacteria and archaea sampled at different soil depths (0–10 and 30–50 cm) from 32 sites along an aridity gradient of 1500 km in the temperate grasslands in northern China, we compared the effects of deterministic and stochastic processes on the taxonomic and phylogenetic β-diversity of soil microbes. Using variation partitioning and null models, we found that the taxonomic β-diversity of the overall bacterial communities was more strongly determined by deterministic processes in both soil layers (the explanatory power of environmental distance in topsoil: 25.4%; subsoil: 47.4%), while their phylogenetic counterpart was more strongly determined by stochastic processes (the explanatory power of spatial distance in topsoil: 42.1; subsoil 24.7%). However, in terms of abundance, both the taxonomic and phylogenetic β-diversity of the abundant bacteria in both soil layers was more strongly determined by deterministic processes, while those of rare bacteria were more strongly determined by stochastic processes. In comparison with bacteria, both the taxonomic and phylogenetic β-diversity of the overall abundant and rare archaea were strongly determined by deterministic processes. Among the variables representing deterministic processes, contemporary and historical climate and aboveground vegetation dominated the microbial β-diversity of the overall and abundant microbes of both domains in topsoils, but soil geochemistry dominated in subsoils. This study presents a comprehensive understanding on the β-diversity of soil microbial communities in the temperate grasslands in northern China. Our findings highlight the importance of soil depth, phylogenetic turnover, and species abundance in the assembly processes of soil microbial communities.

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No apparent effect of invasive alien goldenrod on soil microbial communities or soil fauna feeding activity

Acta Oecologica ◽

10.1016/j.actao.2020.103669 ◽

2020 ◽

Vol 109 ◽

pp. 103669

Author(s):

Beata Klimek ◽

Małgorzata Jaźwa ◽

Marcin Gołębiewski ◽

Marcin Sikora ◽

Edyta Deja-Sikora

Keyword(s):

Microbial Communities ◽

Soil Fauna ◽

Feeding Activity ◽

Soil Microbial Communities ◽

Apparent Effect ◽

Soil Microbial

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Plant Community and Nitrogen Deposition as Drivers of Alpha and Beta Diversities of Prokaryotes in Reconstructed Oil Sand Soils and Natural Boreal Forest Soils

Applied and Environmental Microbiology ◽

10.1128/aem.03319-16 ◽

2017 ◽

Vol 83 (9) ◽

Cited By ~ 12

Author(s):

Jacynthe Masse ◽

Cindy E. Prescott ◽

Sébastien Renaut ◽

Yves Terrat ◽

Sue J. Grayston

Keyword(s):

Boreal Forest ◽

Microbial Communities ◽

Nitrogen Deposition ◽

Plant Species ◽

Forest Soils ◽

Soil Microbial Communities ◽

Oil Sand ◽

Soil Microbial ◽

Β Diversity ◽

Α Diversity

ABSTRACT The Athabasca oil sand deposit is one of the largest single oil deposits in the world. Following surface mining, companies are required to restore soil-like profiles that can support the previous land capabilities. The objective of this study was to assess whether the soil prokaryotic alpha diversity (α-diversity) and β-diversity in oil sand soils reconstructed 20 to 30 years previously and planted to one of three vegetation types (coniferous or deciduous trees and grassland) were similar to those found in natural boreal forest soils subject to wildfire disturbance. Prokaryotic α-diversity and β-diversity were assessed using massively parallel sequencing of 16S rRNA genes. The β-diversity, but not the α-diversity, differed between reconstructed and natural soils. Bacteria associated with an oligotrophic lifestyle were more abundant in natural forest soils, whereas bacteria associated with a copiotrophic lifestyle were more abundant in reconstructed soils. Ammonia-oxidizing archaea were most abundant in reconstructed soils planted with grasses. Plant species were the main factor influencing α-diversity in natural and in reconstructed soils. Nitrogen deposition, pH, and plant species were the main factors influencing the β-diversity of the prokaryotic communities in natural and reconstructed soils. The results highlight the importance of nitrogen deposition and aboveground-belowground relationships in shaping soil microbial communities in natural and reconstructed soils. IMPORTANCE Covering over 800 km2, land disturbed by the exploitation of the oil sands in Canada has to be restored. Here, we take advantage of the proximity between these reconstructed ecosystems and the boreal forest surrounding the oil sand mining area to study soil microbial community structure and processes in both natural and nonnatural environments. By identifying key characteristics shaping the structure of soil microbial communities, this study improved our understanding of how vegetation, soil characteristics and microbial communities interact and drive soil functions.

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