Nitrogen fixation and methanotrophy in forest mosses along a N deposition gradient

Leppänen, Sanna M.; Salemaa, Maija; Smolander, Aino; Mäkipää, Raisa; Tiirola, Marja

doi:10.1016/j.envexpbot.2012.12.006

Cited by 89 publications

(94 citation statements)

References 42 publications

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“…5; F 1,12 = 11.92, p < 0.01), indicating competition and/or inhibition by acetylene. The weighted average of the 15 N 2 incorporation in mosses incubated with both acetylene and 15 N 2 generated a conversion factor of 3.11 (mol N 2 fixed/mol C 2 H 2 reduced) similar to those found in other studies (Leppänen et al 2013), although showing high variation (SEM = 1.1).…”

Section: N Label Incorporationsupporting

confidence: 59%

“…In several other studies, conversion factors between acetylene reduction and N 2 fixation rates were calculated by complementing the AR method with 15 N 2 incorporation, resulting in a wide range of values for conversion factors (Leppänen et al 2013;Vile et al 2014;Knorr et al 2014). Unlike in these studies, repeated measurements of the same microcosms in the present study made the use of the otherwise preferable, but destructive 1 5 N 2 uptake method impossible.…”

Section: Methodological Considerationsmentioning

confidence: 68%

“…These results are comparable to observations for nitrogenase activity in forest mosses (Pleurozium spp.) along an N deposition gradient, where sites with higher N deposition showed lower N 2 fixation rates (Leppänen et al 2013). Surprisingly however, nitrogenase activity in Sphagnum mosses with a long-term history of low N deposition strongly decreased upon incubation and repeated ARA, while activity remained equally for the high N site (see BMethodological considerations^below).…”

Section: Discussionmentioning

confidence: 99%

“…12 to 15 mg of each sample was transferred into a 5 × 8 mm tin cup and combusted by flash combustion (1800°C) on a CNS analyzer (EA 1110 Carlo Erba -Thermo Fisher Scientific) coupled to an Isotopic Ratio Mass Spectrometer (Finnigan DeltaPlus, interface Conflo III). Conversion factors were calculated according to Leppänen et al (2013). Background 15 N 2 levels were uniform, for the 10P mosses average Δ15N/14N (‰) was 0.797 ± 0.396.…”

Section: N Fertilization Treatmentsmentioning

confidence: 99%

“…However, when the Pleurozium mosses were experimentally deprived of N, after having been exposed to high N deposition rates, their microbial community reacted with an increase in N 2 fixation rates (Rousk et al 2013b). Similarly, along a natural gradient of N deposition levels, the diazotrophic activity (mainly of cyanobacteria) associated with the forest mosses Hylocomium splendens and P. schreberi was shown to decrease with increasing N deposition levels (Leppänen et al 2013). Studies on the effect of N fertilization on S. fuscum and S. angustifolium-associated diazotrophs in a pristine peat bog showed that the diazotrophic activity was negatively affected by high N input, although moss productivity did not change (Vile et al 2014).…”

Section: Introductionmentioning

confidence: 99%

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Effects of nitrogen fertilization on diazotrophic activity of microorganisms associated with Sphagnum magellanicum

et al. 2016

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Background and aims In pristine ombrotrophic Sphagnum-dominated peatland ecosystems nitrogen (N) is often a limiting nutrient, which is replenished by biological N 2 fixation and atmospheric N deposition. It is, however, unclear which impact long-term N deposition has on microbial N 2 fixing activity and diazotrophic diversity, and whether phosphorus (P) modulates the response. Therefore, we studied the impact of increased N deposition and N depletion on microbial N 2 fixation and diazotrophic diversity associated with the peat moss Sphagnum magellanicum, and their interaction with P availability. Methods Nitrogenase activities of S. magellanicumassociated microorganisms were determined by acetylene reduction assays (ARA) and 15 N 2 tracer methods on mosses from two geographically distinct locations with different N deposition histories, high or low N deposition, and in samples depleted in N (grown 3 years in the greenhouse) versus recent field samples. The short-term response to increased N deposition was tested for mosses differing in N and P fertilization histories. In addition, diversity of diazotrophic microorganisms was assessed by nifH gene amplicon sequencing of N-depleted mosses. Results We showed distinct and persistent differences in diazotrophic communities and their activities associated with S. magellanicum from sites with high versus low N deposition. Initially, diazotrophic activity was six times higher for the low N site. During incubation and repeated ARA, however, this activity strongly decreased, while it remained stable for the high N site. Activity for the high N site could not be increased by long-term experimental N deprivation. Short-term, experimental N application had an inhibitory effect on N 2 fixation for both sites, which was not observed in mosses with high indirect P availability. Conclusions We conclude that although N deposition negatively affects N 2 fixation as also shown in previous studies, long-term effects of N deprivation on the diazotrophic activity and community are more complex. Furthermore, our results indicated that P availability might be an important factor in modulating the response of Sphagnum-associated diazotrophs to N deposition.

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Section: N Label Incorporationsupporting

confidence: 59%

Section: Methodological Considerationsmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 99%

Section: N Fertilization Treatmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effects of nitrogen fertilization on diazotrophic activity of microorganisms associated with Sphagnum magellanicum

et al. 2016

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Modern Topics in the Phototrophic Prokaryotes

Hallenbeck¹

2017

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Filamentous cyanobacteria are important primary producers and N2 fixers in many terrestrial environments. As reduced nitrogen is often limiting, some thalloid liverworts (Marchantiophyta), hornworts (Anthocerophyta), the water fern Azolla (Salviniales), cycads (Cycadophyta), and the angiosperm Gunnera (Gunnerales) have evolved the ability to establish stable and structurally well-defined symbioses with N2-fixing cyanobacteria. Also a wide diversity of lichen-forming fungi have cyanobacteria as photosynthetic symbionts or as N2-fixing symbionts. Cyanolichen symbioses have evolved independently in different fungal lineages, and evolution has often resulted in convergent morphologies in distantly related groups. DNA techniques have provided a wealth of new information on the diversity of symbiotic cyanobacteria and their hosts. The fact that many plants and fungi engage in many different symbioses simultaneously underlines the probable significance of diffuse evolutionary relationships between different symbiotic systems, including cyanobacterial and mycorrhizal associations. This review introduces the reader to recent research on symbiotic cyanobacteria in terrestrial ecosystems and shortly describes the astonishing range of diversity in these ecologically important associations.

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Cyanobacteria in Terrestrial Symbiotic Systems

Rikkinen

2017

Modern Topics in the Phototrophic Prokaryotes

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Filamentous cyanobacteria are important primary producers and N 2 fixers in many terrestrial environments. As reduced nitrogen is often limiting, some thalloid liverworts (Marchantiophyta), hornworts (Anthocerophyta), the water fern Azolla (Salviniales), cycads (Cycadophyta), and the angiosperm Gunnera (Gunnerales) have evolved the ability to establish stable and structurally welldefined symbioses with N 2 -fixing cyanobacteria. Also a wide diversity of lichenforming fungi have cyanobacteria as photosynthetic symbionts or as N 2 -fixing symbionts. Cyanolichen symbioses have evolved independently in different fungal lineages, and evolution has often resulted in convergent morphologies in distantly related groups. DNA techniques have provided a wealth of new information on the diversity of symbiotic cyanobacteria and their hosts. The fact that many plants and fungi engage in many different symbioses simultaneously underlines the probable significance of diffuse evolutionary relationships between different symbiotic systems, including cyanobacterial and mycorrhizal associations. This review introduces the reader to recent research on symbiotic cyanobacteria in terrestrial ecosystems and shortly describes the astonishing range of diversity in these ecologically important associations.

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Nitrogen fixation and methanotrophy in forest mosses along a N deposition gradient

Cited by 89 publications

References 42 publications

Effects of nitrogen fertilization on diazotrophic activity of microorganisms associated with Sphagnum magellanicum

Effects of nitrogen fertilization on diazotrophic activity of microorganisms associated with Sphagnum magellanicum

Modern Topics in the Phototrophic Prokaryotes

Cyanobacteria in Terrestrial Symbiotic Systems

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