Variation in N<sub>2</sub>Fixation in Subarctic Tundra in Relation to Landscape Position and Nitrogen Pools and Fluxes

Diáková, Kateřina; Biasi, Christina; Čapek, Petr; Martikainen, Pertti J.; Marushchak, Maija E.; Патова, Е. Н.; Šantrůčková, Hana

doi:10.1657/aaar0014-064

Cited by 22 publications

(17 citation statements)

References 69 publications

(91 reference statements)

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“…The low NO − 3 consumption in BP suggests that microbial demands are met in BP surfaces. This suggestion agrees with the findings of Diáková et al (2016), who observed significantly higher net N mineralization rates in BP compared with VP, indicating that microbial communities in BP had a surplus of available N. Gross mineralization, nitrification and NO − 3 consumption in VP are negligible, indicating severe N limitations in these soils.…”

Section: Gross Mineralization and Nitrification Rates From Bp And Vp ...supporting

confidence: 91%

Sources of nitrous oxide and the fate of mineral nitrogen in subarctic permafrost peat soils

et al. 2022

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Abstract. Nitrous oxide (N2O) emissions from permafrost-affected terrestrial ecosystems have received little attention, largely because they have been thought to be negligible. Recent studies, however, have shown that there are habitats in the subarctic tundra emitting N2O at high rates, such as bare peat (BP) surfaces on permafrost peatlands. Nevertheless, the processes behind N2O production in these high-emission habitats are poorly understood. In this study, we established an in situ 15N-labeling experiment with two main objectives: (1) to partition the microbial sources of N2O emitted from BP surfaces on permafrost peatlands and (2) to study the fate of ammonium and nitrate in these soils and in adjacent vegetated peat (VP) surfaces showing low N2O emissions. Our results confirm the hypothesis that denitrification is mostly responsible for the high N2O emissions from BP. During the study period, denitrification contributed ∼ 79 % of the total N2O emissions from BP, whereas the contribution from ammonia oxidation was less (about 19 %). Both gross N mineralization and gross nitrification rates were higher in BP than in VP, with high C/N ratios and a low water content likely limiting N transformation processes and, consequently, N2O production in the latter soil type. Our results show that multiple factors contribute to high N2O production in BP surfaces on permafrost peatlands, with the most important factors being the absence of plants, an intermediate to high water content and a low C/N ratio, which all affect the mineral-N availability for soil microbes, including those producing N2O. The process understanding produced here is important for the development of process models that can be used to evaluate future permafrost–N feedbacks to the climate system.

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Section: Gross Mineralization and Nitrification Rates From Bp And Vp ...supporting

confidence: 91%

Sources of nitrous oxide and the fate of mineral nitrogen in subarctic permafrost peat soils

et al. 2022

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“…Soil pH, the key factor influencing soil microorganisms, was not significantly changed by P addition ( Mao et al, 2017 ) and it did not even increase, as shown by a meta-analysis ( Xiao et al, 2018 ). However, P addition directly alters the plant community productivity, especially the legume biomass ( Zhao et al, 2019 ), and it indirectly significantly affects the surrounding microorganisms ( Hartmann et al, 2008 ; Berendsen et al, 2012 ) through rhizodeposition ( Zak et al, 2003 ; Eisenhauer et al, 2010 ) or symbiotic N fixation ( Augusto et al, 2013 ; Diáková et al, 2018 ) and the increasing mycorrhizal colonisation of plant roots ( Lagrange et al, 2013 ). Thus, the effects of P addition on soil microorganisms might be correlated with plant factors, but not with soil factors.…”

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confidence: 99%

Differentiate Responses of Soil Microbial Community and Enzyme Activities to Nitrogen and Phosphorus Addition Rates in an Alpine Meadow

Wang

2022

Front. Plant Sci.

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Nitrogen (N) and phosphorus (P) are the dominant limiting nutrients in alpine meadows, but it is relatively unclear how they affect the soil microbial community and whether their effects are rate dependent. Here, N and P addition rates (0, 10, 20, and 30 g m–2 year–1) were evaluated in an alpine meadow and variables related to plants and soils were measured to determine the processes affecting soil microbial community and enzyme activities. Our results showed that soil microbial biomass, including bacteria, fungi, gramme-negative bacteria, and actinomycetes, decreased along with N addition rates, but they first decreased at low P addition rates (10 g m–2 year–1) and then significantly increased at high P addition rates (30 g m–2 year–1). Both the N and P addition stimulated soil invertase activity, while urease and phosphatase activities were inhibited at low N addition rate and then increased at high N addition rate. P addition generally inhibited peroxidase and urease activities, but increased phosphatase activity. N addition decreased soil pH and, thus, inhibited soil microbial microorganisms, while P addition effects were unimodal with addition rates, achieved through altering sedge, and available P in the soil. In conclusion, our studies indicated that soil microbial communities and enzyme activities are sensitive to short-term N and P addition and are also significantly influenced by their addition rates.

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“…2c). This mechanism is documented for symbiotic N 2 fixation 38,39,40,41 and mycorrhizal colonization of plant roots 42,43 , which increases with P fertilization.…”

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A plant–microbe interaction framework explaining nutrient effects on primary production

et al. 2018

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In most terrestrial ecosystems, plant growth is limited by nitrogen and phosphorus. Adding either nutrient to soil usually affects primary production, but their effects can be positive or negative. Here we provide a general stoichiometric framework for interpreting these contrasting effects. First, we identify nitrogen and phosphorus limitations on plants and soil microorganisms using their respective nitrogen to phosphorus critical ratios. Second, we use these ratios to show how soil microorganisms mediate the response of primary production to limiting and non-limiting nutrient addition along a wide gradient of soil nutrient availability. Using a meta-analysis of 51 factorial nitrogen-phosphorus fertilization experiments conducted across multiple ecosystems, we demonstrate that the response of primary production to nitrogen and phosphorus additions is accurately predicted by our stoichiometric framework. The only pattern that could not be predicted by our original framework suggests that nitrogen has not only a structural function in growing organisms, but also a key role in promoting plant and microbial nutrient acquisition. We conclude that this stoichiometric framework offers the most parsimonious way to interpret contrasting and, until now, unresolved responses of primary production to nutrient addition in terrestrial ecosystems.

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Variation in N₂Fixation in Subarctic Tundra in Relation to Landscape Position and Nitrogen Pools and Fluxes

Cited by 22 publications

References 69 publications

Sources of nitrous oxide and the fate of mineral nitrogen in subarctic permafrost peat soils

Sources of nitrous oxide and the fate of mineral nitrogen in subarctic permafrost peat soils

Differentiate Responses of Soil Microbial Community and Enzyme Activities to Nitrogen and Phosphorus Addition Rates in an Alpine Meadow

A plant–microbe interaction framework explaining nutrient effects on primary production

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Variation in N2Fixation in Subarctic Tundra in Relation to Landscape Position and Nitrogen Pools and Fluxes

Cited by 22 publications

References 69 publications

Sources of nitrous oxide and the fate of mineral nitrogen in subarctic permafrost peat soils

Sources of nitrous oxide and the fate of mineral nitrogen in subarctic permafrost peat soils

Differentiate Responses of Soil Microbial Community and Enzyme Activities to Nitrogen and Phosphorus Addition Rates in an Alpine Meadow

A plant–microbe interaction framework explaining nutrient effects on primary production

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Variation in N₂Fixation in Subarctic Tundra in Relation to Landscape Position and Nitrogen Pools and Fluxes