Microbial biomass and respiration responses to nitrogen fertilization in a polar desert

Ball, Becky A.; Virginia, Ross A.

doi:10.1007/s00300-014-1459-0

Cited by 26 publications

(7 citation statements)

References 60 publications

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“…Therefore, it was speculated that the microbial respiration Q 10 down the slope decreased due to the preferential use of nutrient-rich SOC of microbes when soil is rich in decomposable SOC [ 89 ]. Microbial substrate utilization downslope likely changed from relative more recalcitrant C, such as lignin and cellulose (upper slope position), to simple soluble C (lower slope position), which requires a lower activation energy for chemical and microbial decomposition [ 39 , 90 ]. These are the evidence that erosional distribution of water and substrate leads to differential microbial utilization of SOC at different slope positions.…”

Section: Discussionmentioning

confidence: 99%

Spatial variations of soil respiration and temperature sensitivity along a steep slope of the semiarid Loess Plateau

Sun

Wang

et al. 2018

PLoS ONE

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The spatial heterogeneity of soil respiration and its temperature sensitivity pose a great challenge to accurately estimate the carbon flux in global carbon cycling, which has primarily been researched in flatlands versus hillslope ecosystems. On an eroded slope (35°) of the semiarid Loess Plateau, soil respiration, soil moisture and soil temperature were measured in situ at upper and lower slope positions in triplicate from 2014 until 2016, and the soil biochemical and microbial properties were determined. The results showed that soil respiration was significantly greater (by 44.2%) at the lower slope position (2.6 μmol m–2 s–1) than at the upper slope position, as were soil moisture, carbon, nitrogen fractions and root biomass. However, the temperature sensitivity was 13.2% greater at the upper slope position than at the lower slope position (P < 0.05). The soil fungal community changed from being Basidiomycota-dominant at the upper slope position to being Zygomycota-dominant at the lower slope position, corresponding with increased β-D-glucosidase activity at the upper slope position than at the lower slope position. We concluded that soil respiration was enhanced by the greater soil moisture, root biomass, carbon and nitrogen contents at the lower slope position than at the upper slope position. Moreover, the increased soil respiration and decreased temperature sensitivity at the lower slope position were partially due to copiotrophs replacing oligotrophs. Such spatial variations along slopes must be properly accounted for when estimating the carbon budget and feedback of future climate change on hillslope ecosystems.

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Section: Discussionmentioning

confidence: 99%

Spatial variations of soil respiration and temperature sensitivity along a steep slope of the semiarid Loess Plateau

Sun

Wang

et al. 2018

PLoS ONE

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“…then centrifuged at a low speed, 50 × g , to settle out the coarser sediment particles (at least 1 h at 4°C). The supernatant (2–3 mls), including the cells and the finest sediment fraction was then filtered onto a 0.2 μm polycarbonate filter and stained with 25X SYBR Gold nucleic acid stain (Invitrogen TM ) for 15 min ( Ball and Virginia, 2014 ). Filters were rinsed with 1 ml of 0.2 μm filtered nanopure water and enumerated using epi-fluorescence microscopy (Leica DM5500B with an excitation filter set BP 480/40).…”

Section: Methodsmentioning

confidence: 99%

Microbial sulfur transformations in sediments from Subglacial Lake Whillans

et al. 2014

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Diverse microbial assemblages inhabit subglacial aquatic environments. While few of these environments have been sampled, data reveal that subglacial organisms gain energy for growth from reduced minerals containing nitrogen, iron, and sulfur. Here we investigate the role of microbially mediated sulfur transformations in sediments from Subglacial Lake Whillans (SLW), Antarctica, by examining key genes involved in dissimilatory sulfur oxidation and reduction. The presence of sulfur transformation genes throughout the top 34 cm of SLW sediments changes with depth. SLW surficial sediments were dominated by genes related to known sulfur-oxidizing chemoautotrophs. Sequences encoding the adenosine-5′-phosphosulfate (APS) reductase gene, involved in both dissimilatory sulfate reduction and sulfur oxidation, were present in all samples and clustered into 16 distinct operational taxonomic units. The majority of APS reductase sequences (74%) clustered with known sulfur oxidizers including those within the “Sideroxydans” and Thiobacillus genera. Reverse-acting dissimilatory sulfite reductase (rDSR) and 16S rRNA gene sequences further support dominance of “Sideroxydans” and Thiobacillus phylotypes in the top 2 cm of SLW sediments. The SLW microbial community has the genetic potential for sulfate reduction which is supported by experimentally measured low rates (1.4 pmol cm-3d-1) of biologically mediated sulfate reduction and the presence of APS reductase and DSR gene sequences related to Desulfobacteraceae and Desulfotomaculum. Our results also infer the presence of sulfur oxidation, which can be a significant energetic pathway for chemosynthetic biosynthesis in SLW sediments. The water in SLW ultimately flows into the Ross Sea where intermediates from subglacial sulfur transformations can influence the flux of solutes to the Southern Ocean.

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“…Warmer temperatures increase the availability of meltwater from permafrost and glaciers, affecting N-cycling by soil microbial communities [ 116 , 121 ]. For instance, warm and wet conditions stimulated microbial activity when glycine and tryptic soy broth were added to a maritime Antarctic soil in the Signy Island [ 122 ], resulting in the increase in both organic and inorganic N. In particular, the input of carbon in Antarctic soils (either through meltwater or other sources) has been shown to significantly change the kinetics of N-cycling, resulting in net N immobilization [ 117 , 118 ] and changes in the N mineralization process [ 108 , 118 , 119 , 122 , 123 ].…”

Section: N Supplementation Experimentsmentioning

confidence: 99%

Microbial Nitrogen Cycling in Antarctic Soils

et al. 2020

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The Antarctic continent is widely considered to be one of the most hostile biological habitats on Earth. Despite extreme environmental conditions, the ice-free areas of the continent, which constitute some 0.44% of the total continental land area, harbour substantial and diverse communities of macro-organisms and especially microorganisms, particularly in the more “hospitable” maritime regions. In the more extreme non-maritime regions, exemplified by the McMurdo Dry Valleys of South Victoria Land, nutrient cycling and ecosystem servicing processes in soils are largely driven by microbial communities. Nitrogen turnover is a cornerstone of ecosystem servicing. In Antarctic continental soils, specifically those lacking macrophytes, cold-active free-living diazotrophic microorganisms, particularly Cyanobacteria, are keystone taxa. The diazotrophs are complemented by heterotrophic bacterial and archaeal taxa which show the genetic capacity to perform elements of the entire N cycle, including nitrification processes such as the anammox reaction. Here, we review the current literature on nitrogen cycling genes, taxa, processes and rates from studies of Antarctic soils. In particular, we highlight the current gaps in our knowledge of the scale and contribution of these processes in south polar soils as critical data to underpin viable predictions of how such processes may alter under the impacts of future climate change.

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Microbial biomass and respiration responses to nitrogen fertilization in a polar desert

Cited by 26 publications

References 60 publications

Spatial variations of soil respiration and temperature sensitivity along a steep slope of the semiarid Loess Plateau

Spatial variations of soil respiration and temperature sensitivity along a steep slope of the semiarid Loess Plateau

Microbial sulfur transformations in sediments from Subglacial Lake Whillans

Microbial Nitrogen Cycling in Antarctic Soils

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