Long-Term Experimental Nitrogen Deposition Alters the Composition of the Active Fungal Community in the Forest Floor

Entwistle, Elizabeth; Zak, Donald R.; Edwards, Ivan P.

doi:10.2136/sssaj2013.05.0179

Cited by 46 publications

(47 citation statements)

References 75 publications

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“…The ACE and Chao1 indices reveal that the high N-added crust contains a higher richness than do the other crusts (Table 2). These findings contrast with previous studies (Porras-Alfaro et al, 2011;Entwistle et al, 2013), which found no significant shifts in Chao1 richness and inverse Simpson diversity with N addition and significantly lower or no change in the Shannon diversity with N addition, but our work is partly consistent with the work by Robinson et al (2004), in which low N addition (0.5 g N m À2 y À1 ) could marginally increase the fungal species richness in a high Arctic polar semidesert ecosystem. Interestingly, our results also revealed that a large proportion of the fungal diversity corresponds to nonassignable fungal sequences (no_rank_Fungi and unclassified_Fungi), which made up the second most common group next to Ascomycota in the control, low-N and medium-N crusts and mostly dominated in the high-N crusts.…”

Section: Shifts Of Fungal Diversity and Communitiescontrasting

confidence: 99%

“…Amongst other changes, a shift towards bacteria-dominated microbial communities is expected (Tietema, 1998). Changes in the diversity and composition of soil microbial community after N addition have recently received increased attention in ecosystems, including forests (Entwistle et al, 2013), steppes (Zhang et al, 2008), grasslands and agriculture fields (Ramirez et al, 2010), and alpine tundras (Nemergut et al, 2008). A consensus of recent studies suggests that excess soil N reduces microbial biomass and activity and decreases the soil microbial respiration levels (Ramirez et al, 2010(Ramirez et al, , 2012.…”

Section: Introductionmentioning

confidence: 99%

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Impact of inorganic nitrogen additions on microbes in biological soil crusts

Wang

Bao

et al. 2015

Soil Biology and Biochemistry

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Section: Shifts Of Fungal Diversity and Communitiescontrasting

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impact of inorganic nitrogen additions on microbes in biological soil crusts

Wang

Bao

et al. 2015

Soil Biology and Biochemistry

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“…Such responses have been previously noted; N enrichment elicited a shift in bacterial community composition in agricultural, alpine, tundra, and grassland soils (63)(64)(65)(66) as well as in laboratory assays in soil from 28 sites across the United States (67). Similarly, ectomycorrhizal and saprotrophic fungal compositions are sensitive to N enrichment (32,61,68).…”

Section: Discussionsupporting

confidence: 62%

“…Our observations add to an existing body of literature detailing ecosystem responses to long-term experimental N deposition in a northern hardwood ecosystem (Fig. 4), wherein 20 years of experimental N deposition has led to increased N in soil solution and plant litter, which together have repressed the activities of fungal lignocellulolytic exoenzymes and fungal laccase expression, leading to incomplete lignin decay and increased SOM accumulation and phenolic DOC leaching (6,32,68,72). In this report, we present evidence that a more abundant, less diverse, and compositionally different bacterial LMCO assemblage occurred concomitantly with a decreased extent of litter decay and increased DOC production in our long-term field experiment, supporting the hypothesis that experimental N deposition favors bacteria with the physiological ability to metabolize both plant litter and humidified soil organic matter.…”

Section: Discussionmentioning

confidence: 52%

Atmospheric N Deposition Increases Bacterial Laccase-Like Multicopper Oxidases: Implications for Organic Matter Decay

Freedman

Zak

2014

Appl Environ Microbiol

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Anthropogenic release of biologically available nitrogen (N) has increased dramatically over the last 150 years, which can alter the processes controlling carbon (C) storage in terrestrial ecosystems. In a northern hardwood forest ecosystem located in Michigan in the United States, nearly 20 years of experimentally increased atmospheric N deposition has reduced forest floor decay and increased soil C storage. This change occurred concomitantly with compositional changes in Basidiomycete fungi and in Actinobacteria, as well as the downregulation of fungal lignocelluloytic genes. Recently, laccase-like multicopper oxidases (LMCOs) have been discovered among bacteria which can oxidize ␤-O-4 linkages in phenolic compounds (e.g., lignin and humic compounds), resulting in the production of dissolved organic carbon (DOC). Here, we examined how nearly 2 decades of experimental N deposition has affected the abundance and composition of saprotrophic bacteria possessing LMCO genes. In our experiment, LMCO genes were more abundant in the forest floor under experimental N deposition whereas the abundances of bacteria and fungi were unchanged. Experimental N deposition also led to less-diverse, significantly altered bacterial and LMCO gene assemblages, with taxa implicated in organic matter decay (i.e., Actinobacteria, Proteobacteria) accounting for the majority of compositional changes. These results suggest that experimental N deposition favors bacteria in the forest floor that harbor the LMCO gene and represents a plausible mechanism by which anthropogenic N deposition has reduced decomposition, increased soil C storage, and accelerated phenolic DOC production in our field experiment. Our observations suggest that future rates of atmospheric N deposition could fundamentally alter the physiological potential of soil microbial communities.

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“…Nearby our study site, Chen et al (2012) reported that NH 4 NO 3 addition at rates of 7.5 and 15 g N m −2 year −1 significantly decreased the C/N ratio of masson pine litter by 27.6 % in a 540-day incubation study. The molecular mechanism mediating a decline in microbial activity under high level of N addition is the transcriptional downregulation of fungal genes encoding phenol oxidase, Mn peroxidase, and lignin peroxidase (Hassett et al 2009;Entwistle et al 2013). Such a response could translate a decline in organic matter decomposition (Zak et al 2008).…”

Section: Discussionmentioning

confidence: 99%

Contrasting effects of ammonium and nitrate inputs on soil CO2 emission in a subtropical coniferous plantation of southern China

et al. 2015

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Increased nitrogen (N) deposition has been found controversial affecting soil CO 2 emission in terrestrial ecosystems, which leads to serious debate on the efficiency of estimated C sequestration induced by N enrichment. The forms of input N might be responsible for this controversy. This study aims to explore the effects of NH 4 + (reduced N) and NO 3 − (oxidized N) on soil CO 2 flux and the underlying microbial mechanisms. An N addition experiment, two N fertilizers (NH 4 Cl and NaNO 3 ) and two rates (40 and 120 kg N ha −1 year −1 ), was carried out in a slash pine plantation of southern China. Soil-atmospheric CO 2 exchange, soil microbial biomass, and community composition were measured using static chamber-gas chromatography and phospholipid fatty acid (PLFA) analyses in the active growing and nonactive growing seasons, respectively. Low level of NaNO 3 addition significantly increased soil CO 2 flux in the active growing season, whereas other N treatments did not change soil CO 2 flux. High level of NH 4 Cl addition significantly reduced soil fungal biomass (fungal PLFA) and changed microbial community composition (ratio of fungal to bacterial (F/B) PLFAs). The positive relationships between the change in soil CO 2 flux and the change in fungal biomass, as well as between the change in soil CO 2 flux and the change in community composition, were observed in the nonactive growing season. The N forms as NO 3 − or NH 4 + are important factors affecting C cycles in the subtropical coniferous plantation. These results suggested that the variations of soil CO 2 emission and microbial biomass and community composition in the subtropical plantation depended on the seasons and the levels and forms of N addition.

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Long-Term Experimental Nitrogen Deposition Alters the Composition of the Active Fungal Community in the Forest Floor

Cited by 46 publications

References 75 publications

Impact of inorganic nitrogen additions on microbes in biological soil crusts

Impact of inorganic nitrogen additions on microbes in biological soil crusts

Atmospheric N Deposition Increases Bacterial Laccase-Like Multicopper Oxidases: Implications for Organic Matter Decay

Contrasting effects of ammonium and nitrate inputs on soil CO2 emission in a subtropical coniferous plantation of southern China

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