scholarly journals The core root microbiome of Spartina alterniflora is predominated by sulfur-oxidizing and sulfate-reducing bacteria in Georgia salt marshes, USA

2021 ◽  
Author(s):  
Jose L Rolando ◽  
Max Kolton ◽  
Tianze Song ◽  
Joel E. Kostka
Keyword(s):  
Spartina Alterniflora ◽  
Primary Productivity ◽  
Salt Marshes ◽  
Root Zone ◽  
N Fixation ◽  
Core Microbiome ◽  
Sulfate Reducing ◽  
C And N ◽  
S Oxidation ◽  
Root Microbiome

Background: Salt marshes are dominated by the smooth cordgrass Spartina alterniflora on the US Atlantic and Gulf of Mexico coastlines. Although soil microorganisms are well known to mediate important biogeochemical cycles in salt marshes, little is known about the role of root microbiomes in supporting the health and productivity of marsh plant hosts. Leveraging in situ gradients in aboveground plant biomass as a natural laboratory, we investigated the relationships between S. alterniflora primary productivity, sediment redox potential, and the physiological ecology of bulk sediment, rhizosphere, and root microbial communities at two Georgia barrier islands over two growing seasons. Results: A marked decrease in prokaryotic alpha diversity with high abundance and increased phylogenetic dispersion was found in the S. alterniflora root microbiome. Significantly higher rates of enzymatic organic matter decomposition, as well as the relative abundances of putative sulfur (S)-oxidizing, sulfate-reducing, and nitrifying prokaryotes correlated with plant productivity. Moreover, these functional guilds were overrepresented in the S. alterniflora rhizosphere and root core microbiomes. Core microbiome bacteria from the Candidatus Thiodiazotropha genus, with the metabolic potential to couple S oxidation with C and N fixation, were shown to be highly abundant in the root and rhizosphere of S. alterniflora. Conclusions: The S. alterniflora root microbiome is dominated by highly active and competitive species taking advantage of available carbon substrates in the oxidized root zone. Two microbially-mediated mechanisms are proposed to stimulate S. alterniflora primary productivity: (i.) Enhanced microbial activity replenishes nutrients and terminal electron acceptors in higher biomass stands, and (ii.) coupling of chemolithotrophic S oxidation with carbon (C) and nitrogen (N) fixation by root and rhizosphere associated prokaryotes detoxify sulfide in the root zone while potentially transferring fixed C and N to the host plant.

scholarly journals The Impact of Sea Embankment Reclamation on Greenhouse Gas GHG Fluxes and Stocks in Invasive Spartina alterniflora and Native Phragmites australis Wetland Marshes of East China

2021 ◽  
Vol 13 (22) ◽  
pp. 12740
Author(s):  
Jian Li ◽  
Zhanrui Leng ◽  
Yueming Wu ◽  
Guanlin Li ◽  
Guangqian Ren ◽  
...  
Keyword(s):  
Salt Marsh ◽  
Greenhouse Gas ◽  
Spartina Alterniflora ◽  
Phragmites Australis ◽  
Salt Marshes ◽  
Coastal Wetlands ◽  
Organic N ◽  
C And N ◽  
The Impact ◽  
Ghg Fluxes

The introduction of embankment seawalls to limit the expansion of the exotic C4 perennial grass Spartina alteniflora Loisel in eastern China’s coastal wetlands has more than doubled in the past decades. Previous research focused on the impact of sea embankment reclamation on the soil organic carbon (C) and nitrogen (N) stocks in salt marshes, whereas no study attempted to assess the impact of sea embankment reclamation on greenhouse gas (GHG) fluxes in such marshes. Here we examined the impact of sea embankment reclamation on GHG stocks and fluxes of an invasive Spartina alterniflora and native Phragmites australis dominated salt marsh in the Dongtai wetlands of China’s Jiangsu province. Sea embankment reclamation significantly decreased soil total organic C by 54.0% and total organic N by 73.2%, decreasing plant biomass, soil moisture, and soil salinity in both plants’ marsh. It increased CO2 emissions by 38.2% and 13.5%, and reduced CH4 emissions by 34.5% and 37.1%, respectively, in the Spartina alterniflora and Phragmites australis marshes. The coastal embankment wall also significantly increased N2O emission by 48.9% in the Phragmites australis salt marsh and reduced emissions by 17.2% in the Spartina alterniflora marsh. The fluxes of methane CH4 and carbon dioxide CO2 were similar in both restored and unrestored sections, whereas the fluxes of nitrous oxide N2O were substantially different owing to increased nitrate as a result of N-loading. Our findings show that sea embankment reclamation significantly alters coastal marsh potential to sequester C and N, particularly in native Phragmites australis salt marshes. As a result, sea embankment reclamation essentially weakens native and invasive saltmarshes’ C and N sinks, potentially depleting C and N sinks in coastal China’s wetlands. Stakeholders and policymakers can utilize this scientific evidence to strike a balance between seawall reclamation and invasive plant expansion in coastal wetlands.

scholarly journals A model using marginal efficiency of investment to analyze carbon and nitrogen interactions in terrestrial ecosystems (ACONITE Version 1)

2014 ◽  
Vol 7 (5) ◽  
pp. 2015-2037 ◽  
Author(s):  
R. Q. Thomas ◽  
M. Williams
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Primary Productivity ◽  
N Uptake ◽  
Terrestrial Ecosystems ◽  
N Fixation ◽  
Earth System ◽  
Area Index ◽  
Temperate Deciduous ◽  
C And N

Abstract. Carbon (C) and nitrogen (N) cycles are coupled in terrestrial ecosystems through multiple processes including photosynthesis, tissue allocation, respiration, N fixation, N uptake, and decomposition of litter and soil organic matter. Capturing the constraint of N on terrestrial C uptake and storage has been a focus of the Earth System Modeling community. However, there is little understanding of the trade-offs and sensitivities of allocating C and N to different tissues in order to optimize the productivity of plants. Here we describe a new, simple model of ecosystem C–N cycling and interactions (ACONITE), that builds on theory related to plant economics in order to predict key ecosystem properties (leaf area index, leaf C : N, N fixation, and plant C use efficiency) based on the outcome of assessments of the marginal change in net C or N uptake associated with a change in allocation of C or N to plant tissues. We simulated and evaluated steady-state ecosystem stocks and fluxes in three different forest ecosystems types (tropical evergreen, temperate deciduous, and temperate evergreen). Leaf C : N differed among the three ecosystem types (temperate deciduous < tropical evergreen < temperature evergreen), a result that compared well to observations from a global database describing plant traits. Gross primary productivity (GPP) and net primary productivity (NPP) estimates compared well to observed fluxes at the simulation sites. Simulated N fixation at steady-state, calculated based on relative demand for N and the marginal return on C investment to acquire N, was an order of magnitude higher in the tropical forest than in the temperate forest, consistent with observations. A sensitivity analysis revealed that parameterization of the relationship between leaf N and leaf respiration had the largest influence on leaf area index and leaf C : N. A parameter governing how photosynthesis scales with day length had the largest influence on total vegetation C, GPP, and NPP. Multiple parameters associated with photosynthesis, respiration, and N uptake influenced the rate of N fixation. Overall, our ability to constrain leaf area index and allow spatially and temporally variable leaf C : N can help address challenges simulating these properties in ecosystem and Earth System models. Furthermore, the simple approach with emergent properties based on coupled C–N dynamics has potential for use in research that uses data-assimilation methods to integrate data on both the C and N cycles to improve C flux forecasts.

scholarly journals Elucidation of the rhizosphere microbiome linked to Spartina alterniflora phenotype in a salt marsh on Skidaway Island, Georgia, USA

2020 ◽  
Vol 96 (4) ◽  
Author(s):  
Max Kolton ◽  
José L Rolando ◽  
Joel E Kostka
Keyword(s):  
Salt Marsh ◽  
Spartina Alterniflora ◽  
Salt Marshes ◽  
Root Zone ◽  
The United States ◽  
Microbial Interactions ◽  
Tall Plant ◽  
Plant Phenotype ◽  
Selective Forces ◽  
Oxidation Chemistry

ABSTRACT Smooth cordgrass, Spartina alterniflora, dominates salt marshes on the east coast of the United States. While the physicochemical cues affecting S. alterniflora productivity have been studied intensively, the role of plant–microbe interactions in ecosystem functioning remains poorly understood. Thus, in this study, the effects of S. alterniflora phenotype on the composition of archaeal, bacterial, diazotrophic and fungal communities were investigated. Overall, prokaryotic communities were more diverse and bacteria were more abundant in the areas colonized by the tall plant phenotype in comparison to those of short plant phenotype. Diazotrophic methanogens (Methanomicrobia) preferentially colonized the area of the short plant phenotype. Putative iron-oxidizing Zetaproteobacteria and sulfur-oxidizing Campylobacteria were identified as indicator species in the rhizosphere of tall and short plant phenotypes, respectively. Finally, while diazotrophic populations shaped microbial interactions in the areas colonized by the tall plant phenotype, fungal populations filled this role in the areas occupied by the short plant phenotype. The results here demonstrate that S. alterniflora phenotype and proximity to the root zone are selective forces dictating microbial community assembly. Results further reveal that reduction–oxidation chemistry is a major factor driving the selection of belowground microbial populations in salt marsh habitats.

Nitrogen cycling in microbial mat communities: The quantitative importance of N-fixation and other sources of N for primary productivity

1994 ◽  
pp. 265-271 ◽  
Author(s):  
Brad M. Bebout ◽  
Hans W. Paerl ◽  
James E. Bauer ◽  
Donald E. Canfield ◽  
David J. Des Marais
Keyword(s):  
Nitrogen Cycling ◽  
Primary Productivity ◽  
Microbial Mat ◽  
N Fixation ◽  
Quantitative Importance

Dieback of Salt-water Cordgrass (Spartina alterniflora Loisel.) in the Lower Cape Fear Estuary of North Carolina: An Experimental Approach to Re-establishment

1980 ◽  
Vol 7 (1) ◽  
pp. 59-66 ◽  
Author(s):  
Rick A. Linthurst ◽  
Ernest D. Seneca
Keyword(s):  
North Carolina ◽  
Spartina Alterniflora ◽  
Salt Marshes ◽  
Salt Water ◽  
High Water ◽  
The United States ◽  
Salicornia Europaea ◽  
Web Studies ◽  
Mean High Water ◽  
Cape Fear

Spartina alterniflora is the dominant endemic saltmarsh angiosperm along the East and Gulf coasts of the United States. Dieback of S. alterniflora became evident through aerial surveys of the Lower Cape Fear Estuary of North Carolina. The areas affected varied in size, the largest being greater than 40 ha in areal extent. As S. alterniflora productivity losses can subsequently affect the productivity of the estuarine detritus-based food-web, studies were initiated in 1975 to examine the dieback phenomenon, follow successional trends, and determine the recolonization potential of S. alterniflora in dieback-affected salt-marshes.Three S. alterniflora dieback sites in the Lower Cape Fear Estuary were selected for study. Two of the sites, both above mean high-water, were recolonized by Salicornia europaea, Distichlis spicata, Scirpus robustus, Spartina patens, and S. alterniflora. At a third site, found to be below mean high-water, all volunteer plants were of S. alterniflora. Final stabilization of all three sites was mainly by S. alterniflora, with the living standing-crop biomass ranging from 341 to 1,565 g/m2 in September of 1978.Experimental plots within each of the three dieback sites were sprigged with S. alterniflora plants from three sources: (i) sandy dredge-material, (ii) volunteer plants within affected sites, and (iii) unaffected sites near the dieback areas. The success of these sprigs was strongly site-dependent. It is suggested that the plants used for revegetation of dieback sites should be obtained from areas similar to the site that is being transplanted and/or plants which have large rhizome systems.

scholarly journals Recovery and Phylogenetic Analysis ofnifH Sequences from Diazotrophic Bacteria Associated with Dead Aboveground Biomass of Spartina alterniflora

2001 ◽  
Vol 67 (11) ◽  
pp. 5308-5314 ◽  
Author(s):  
Charles R. Lovell ◽  
Michael J. Friez ◽  
John W. Longshore ◽  
Christopher E. Bagwell
Keyword(s):  
South Carolina ◽  
Spartina Alterniflora ◽  
Salt Marshes ◽  
Gel Electrophoresis ◽  
Azospirillum Brasilense ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Diazotrophic Bacteria ◽  
The North ◽  
Standing Dead ◽  
Gradient Gel Electrophoresis

ABSTRACT DNA was extracted from dry standing dead Spartina alterniflora stalks as well as dry Spartinawrack from the North Inlet (South Carolina) and Sapelo Island (Georgia) salt marshes. Partial nifH sequences were PCR amplified, the products were separated by denaturing gradient gel electrophoresis (DGGE), and the prominent DGGE bands were sequenced. Most sequences (109 of 121) clustered with those from α-Proteobacteria, and 4 were very similar (>99%) to that of Azospirillum brasilense. Seven sequences clustered with those from known γ-Proteobacteria and five with those from known anaerobic diazotrophs. The diazotroph assemblages associated with dead Spartina biomass in these two salt marshes were very similar, and relatively few major lineages were represented.

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