Effects of snow cover on CO 2 production and microbial composition in a thin topsoil layer

2020 ◽  
Author(s):  
Dalia López ◽  
Francisco Matus ◽  
Carolina Merino
Keyword(s):  
Organic Matter ◽  
Microbial Community ◽  
Redox Potential ◽  
Snow Cover ◽  
Soil Microbiology ◽  
Snow Melting ◽  
Freezing And Thawing ◽  
Microbial Composition ◽  
Clear Cut ◽  
Organic Matter Mineralization

<p>Temperate rain forest soils (>8000 mm yr -1 ) of south of Chile in the East Andes range are<br>intensively affected by increasing freezing and thawing cycles (FTC) due to increasing<br>climate variability in the last 20 years. Most of these volcanic forests soils are unpolluted<br>(pristine) and receive seasonal snow-cover. In spite of pollutant free precipitations, the<br>snow cover in these ecosystems contains aerosols, nutrients and microorganisms from<br>circumpolar south west winds. These inputs and FTC generate specific conditions at the<br>shallow layer at the soil surface for soil microbiology and biochemistry. The objectives of<br>the study were to compare (micro)biological and chemical properties of topsoil and snow<br>cover in an pristine forest and after clear-cut. The organic matter mineralization was<br>monitored in a microcosm experiment to explore the effects of FTC and snow melting on<br>redox potential and other topsoil parameters. FTC for soil+snow released more CO 2 in<br>closed forest (81.9 mg CO 2 kg -1 ) than that after clear-cut (20.5 mg CO 2 kg -1 ). Soil texture<br>and soil organic matter accumulation played a crucial role for organic matter mineralization<br>and CO 2 fluxes. Gradually increase of temperature after freezing reveled that loamy soils<br>with certain amount of available C maintain active microbial population that response very<br>fast to temperature change. Sandy soils with very low C content showed the opposite<br>results – very slow response of microbial community and CO 2 fluxes. In conclusion,<br>microbial community structure and functions have distinct transition from snow to the soil<br>in temperate snow-covered forest ecosystem. FTC showed that different microbial groups</p><p>are responsible for organic matter mineralization in soil under forest and clear-cut, because<br>the pH and redox potential are influenced by snow melting.</p>

Influence of moisture and freeze–thaw on leaf microbial community dynamics

2010 ◽  
Vol 40 (2) ◽  
pp. 394-400 ◽  
Author(s):  
C. Corrigan ◽  
M. Oelbermann
Keyword(s):  
Organic Matter ◽  
Community Structure ◽  
Microbial Community ◽  
Sugar Maple ◽  
Community Dynamics ◽  
Nitrogen Concentration ◽  
Fagus Grandifolia ◽  
Nutrient Inputs ◽  
Freezing And Thawing ◽  
Freeze Thaw

In forest ecosystems, litterfall that collects in trapping devices, to quantify organic matter and nutrient inputs, is exposed to periods of wetting, drying, freezing, and thawing. These fluctuating environmental conditions may influence the microbial community structure inhabiting the leaves and may result in the loss of mobile nutrients, leading to an underestimation of actual organic matter and nutrient inputs. The objectives of this study were to evaluate the influence of (i) different quantities of moisture (LOW = 30 mm, MED = 60 mm, HI = 100 mm) and (ii) freeze–thaw (FT) on leaf (sugar maple ( Acer saccharum Marsh.), American basswood ( Tilia americana L.), and American beech ( Fagus grandifolia Ehrh.)) microbial activity and community structure. There was a significantly greater (p < 0.05) CO2 production rate in LOW and FT treatments for sugar maple and beech, and in HI and FT treatments for basswood. A similar trend occurred for leaf nitrogen concentration but not for carbon (C). Utilization of C substrates was up to 10% greater in the FT treatments. Principal components analysis on the activity of C source utilization showed a distinct clustering between leaf species and between treatments following a pattern similar to that of microbial respiration. Results from this study suggested that the collection of litter should take place more frequently during seasons when frost is imminent.

scholarly journals Host reproductive cycle influences the pouch microbiota of wild southern hairy-nosed wombats (Lasiorhinus latifrons)

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Sesilje Weiss ◽  
David Taggart ◽  
Ian Smith ◽  
Kristofer M. Helgen ◽  
Raphael Eisenhofer
Keyword(s):  
Microbial Community ◽  
Reproductive Cycle ◽  
Tammar Wallaby ◽  
The Body ◽  
Rrna Gene ◽  
Microbial Composition ◽  
Birth Canal ◽  
Gram Positive Bacteria ◽  
Rigorous Framework ◽  
The 16S Rrna Gene

Abstract Background Marsupials are born much earlier than placental mammals, with most crawling from the birth canal to the protective marsupium (pouch) to further their development. However, little is known about the microbiology of the pouch and how it changes throughout a marsupial’s reproductive cycle. Here, using stringent controls, we characterized the microbial composition of multiple body sites from 26 wild Southern Hairy-nosed Wombats (SHNWs), including pouch samples from animals at different reproductive stages. Results Using qPCR of the 16S rRNA gene we detected a microbial community in the SHNW pouch. We observed significant differences in microbial composition and diversity between the body sites tested, as well as between pouch samples from different reproductive stages. The pouches of reproductively active females had drastically lower microbial diversity (mean ASV richness 19 ± 8) compared to reproductively inactive females (mean ASV richness 941 ± 393) and were dominated by gram positive bacteria from the Actinobacteriota phylum (81.7–90.6%), with the dominant families classified as Brevibacteriaceae, Corynebacteriaceae, Microbacteriaceae, and Dietziaceae. Three of the five most abundant sequences identified in reproductively active pouches had closest matches to microbes previously isolated from tammar wallaby pouches. Conclusions This study represents the first contamination-controlled investigation into the marsupial pouch microbiota, and sets a rigorous framework for future pouch microbiota studies. Our results indicate that SHNW pouches contain communities of microorganisms that are substantially altered by the host reproductive cycle. We recommend further investigation into the roles that pouch microorganisms may play in marsupial reproductive health and joey survival.

T4-like Phages Reveal the Potential Role of Viruses in Soil Organic Matter Mineralization

2021 ◽  
Author(s):  
Xiaomeng Wei ◽  
Tida Ge ◽  
Chuanfa Wu ◽  
Shuang Wang ◽  
Kyle Mason-Jones ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Potential Role ◽  
Organic Matter Mineralization

scholarly journals Microbial Community Structure Affects Marine Dissolved Organic Matter Composition

2016 ◽  
Vol 3 ◽  
Author(s):  
Elizabeth B. Kujawinski ◽  
Krista Longnecker ◽  
Katie L. Barott ◽  
Ralf J. M. Weber ◽  
Melissa C. Kido Soule
Keyword(s):  
Organic Matter ◽  
Community Structure ◽  
Microbial Community ◽  
Dissolved Organic Matter ◽  
Microbial Community Structure ◽  
Organic Matter Composition

scholarly journals Disentangling Responses of the Subsurface Microbiome to Wetland Status and Implications for Indicating Ecosystem Functions

2021 ◽  
Vol 9 (2) ◽  
pp. 211
Author(s):  
Jie Gao ◽  
Miao Liu ◽  
Sixue Shi ◽  
Ying Liu ◽  
Yu Duan ◽  
...  
Keyword(s):  
Microbial Community ◽  
High Throughput Sequencing ◽  
Carbon Fixation ◽  
Microbial Community Composition ◽  
Ecosystem Functions ◽  
Microbial Composition ◽  
Wetland Ecosystems ◽  
Soil Microbial ◽  
Geochemical Properties ◽  
Microbial Groups

In this study, we analyzed microbial community composition and the functional capacities of degraded sites and restored/natural sites in two typical wetlands of Northeast China—the Phragmites marsh and the Carex marsh, respectively. The degradation of these wetlands, caused by grazing or land drainage for irrigation, alters microbial community components and functional structures, in addition to changing the aboveground vegetation and soil geochemical properties. Bacterial and fungal diversity at the degraded sites were significantly lower than those at restored/natural sites, indicating that soil microbial groups were sensitive to disturbances in wetland ecosystems. Further, a combined analysis using high-throughput sequencing and GeoChip arrays showed that the abundance of carbon fixation and degradation, and ~95% genes involved in nitrogen cycling were increased in abundance at grazed Phragmites sites, likely due to the stimulating impact of urine and dung deposition. In contrast, the abundance of genes involved in methane cycling was significantly increased in restored wetlands. Particularly, we found that microbial composition and activity gradually shifts according to the hierarchical marsh sites. Altogether, this study demonstrated that microbial communities as a whole could respond to wetland changes and revealed the functional potential of microbes in regulating biogeochemical cycles.

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