Flooded Soils

Conrad, Ralf; Frenzel, Peter

doi:10.1002/0471263397.env034

Cited by 16 publications

(11 citation statements)

References 279 publications

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“…Still, these values are lower than those obtained for mature biocrusts from the Negev Desert (Angel et al, 2012), indicating either that these Himalayan crusts still undergo development, or that cold desert crust inherently harbor a smaller methanogenic community. The numbers of methanogens were also much lower than the densities observed in anoxic soils such as rice fields (usually 10 6 to 10 7 copies gdw −1 ; Conrad and Frenzel, 2002). …”

Section: Discussionmentioning

confidence: 90%

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas

et al. 2013

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Methanogens typically occur in reduced anoxic environments. However, in recent studies it has been shown that many aerated upland soils, including desert soils also host active methanogens. Here we show that soil samples from high-altitude cold deserts in the western Himalayas (Ladakh, India) produce CH4 after incubation as slurry under anoxic conditions at rates comparable to those of hot desert soils. Samples of matured soil from three different vegetation belts (arid, steppe, and subnival) were compared with younger soils originating from frontal and lateral moraines of receding glaciers. While methanogenic rates were higher in the samples from matured soils, CH4 was also produced in the samples from the recently deglaciated moraines. In both young and matured soils, those covered by a biological soil crust (biocrust) were more active than their bare counterparts. Isotopic analysis showed that in both cases CH4 was initially produced from H2/CO2 but later mostly from acetate. Analysis of the archaeal community in the in situ soil samples revealed a clear dominance of sequences related to Thaumarchaeota, while the methanogenic community comprised only a minor fraction of the archaeal community. Similar to other aerated soils, the methanogenic community was comprised almost solely of the genera Methanosarcina and Methanocella, and possibly also Methanobacterium in some cases. Nevertheless, ~103 gdw−1 soil methanogens were already present in the young moraine soil together with cyanobacteria. Our results demonstrate that Methanosarcina and Methanocella not only tolerate atmospheric oxygen but are also able to survive in these harsh cold environments. Their occurrence in newly deglaciated soils shows that they are early colonizers of desert soils, similar to cyanobacteria, and may play a role in the development of desert biocrusts.

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Section: Discussionmentioning

confidence: 90%

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas

et al. 2013

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“…One of the interesting characteristics of vegetated soils, and particularly of wetland soils, is their heterogeneity in space and time (Paul and Clark, 1989; Conrad and Frenzel, 2002; Bodelier, 2011). Microbiological batch experiments, even those containing multiple organisms, hardly resemble these soils.…”

Section: Heterogeneity In Soils Drives Biodiversity and Functioningmentioning

confidence: 99%

Microbial Transformations of Nitrogen, Sulfur, and Iron Dictate Vegetation Composition in Wetlands: A Review

Lamers¹,

Diggelen²,

Camp³

et al. 2012

Front. Microbio.

108

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The majority of studies on rhizospheric interactions focus on pathogens, mycorrhizal symbiosis, or carbon transformations. Although the biogeochemical transformations of N, S, and Fe have profound effects on vegetation, these effects have received far less attention. This review, meant for microbiologists, biogeochemists, and plant scientists includes a call for interdisciplinary research by providing a number of challenging topics for future ecosystem research. Firstly, all three elements are plant nutrients, and microbial activity significantly changes their availability. Secondly, microbial oxidation with oxygen supplied by radial oxygen loss from roots in wetlands causes acidification, while reduction using alternative electron acceptors leads to generation of alkalinity, affecting pH in the rhizosphere, and hence plant composition. Thirdly, reduced species of all three elements may become phytotoxic. In addition, Fe cycling is tightly linked to that of S and P. As water level fluctuations are very common in wetlands, rapid changes in the availability of oxygen and alternative terminal electron acceptors will result in strong changes in the prevalent microbial redox reactions, with significant effects on plant growth. Depending on geological and hydrological settings, these interacting microbial transformations change the conditions and resource availability for plants, which are both strong drivers of vegetation development and composition by changing relative competitive strengths. Conversely, microbial composition is strongly driven by vegetation composition. Therefore, the combination of microbiological and plant ecological knowledge is essential to understand the biogeochemical and biological key factors driving heterogeneity and total (i.e., microorganisms and vegetation) community composition at different spatial and temporal scales.

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“…Over the past few years, work on paddy soils has mostly been confined to microbiology and concerns about greenhouse gas emissions (Aulakh et al, 2001;Cai et al, 2003Cai et al, , 2005Conrad and Frenzel, 2002;Conrad, 2007;Kimura et al, 2004;Neue and Roger, 2003;Wassmann et al, 2000a,b). When alternative electron acceptors are consumed, equimolar amounts of CO 2 and CH 4 are the end products of anaerobic carbon mineralization (Kirk, 2004).…”

Section: Introduction -General Characteristics Of Paddy Soilsmentioning

confidence: 99%

Biogeochemistry of paddy soils

et al. 2010

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Flooded Soils

Abstract: Biogeochemical Cycling Anaerobic Degradation of Organic Matter to Methane Microbial Oxidation of Methane Microbial Cycling of Oxidants Isotope Effects Competition Among Microorganisms Interaction Between Microorganisms and Plants

Cited by 16 publications

References 279 publications

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas

Methanogens at the top of the world: occurrence and potential activity of methanogens in newly deglaciated soils in high-altitude cold deserts in the Western Himalayas

Microbial Transformations of Nitrogen, Sulfur, and Iron Dictate Vegetation Composition in Wetlands: A Review

Biogeochemistry of paddy soils

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