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

High primary productivity and nitrogen cycling after the Paleoproterozoic phosphogenic event in the Aravalli Supergroup, India

2009 ◽  
Vol 171 (1-4) ◽  
pp. 37-56 ◽  
Author(s):  
Dominic Papineau ◽  
Ritesh Purohit ◽  
Tatiana Goldberg ◽  
Daohui Pi ◽  
Graham A. Shields ◽  
...  
Keyword(s):  
Nitrogen Cycling ◽  
Primary Productivity ◽  
Aravalli Supergroup

scholarly journals Balance between resource supply and demand determines nutrient limitation of primary productivity in the ocean

2016 ◽  
Author(s):  
George I. Hagstrom ◽  
Simon A. Levin ◽  
Adam C. Martiny
Keyword(s):  
Nutrient Cycling ◽  
Primary Productivity ◽  
Supply And Demand ◽  
Marine Ecology ◽  
N Fixation ◽  
P Availability ◽  
Surface Ocean ◽  
Ocean Region ◽  
Limiting Nutrient ◽  
Resource Ratios

AbstractWhat is the ultimate limiting nutrient in the ocean? The dominant theory, which was first proposed by Redfield and later formalized by Tyrrell[1, 2], states that despite the scarcity of fixed nitrogen (N) in the surface ocean, phosphorus (P) availability ultimately determines primary productivity. Two recent findings directly challenge the assumptions of the Redfield-Tyrrell paradigm: the discovery of systematic variations of phytoplankton cellular N:P:Fe and widespread iron-limitation of phytoplankton. Here we use a simple model of nitrogen, phosphorus, and iron (Fe) cycling to show how the resource demand ratios and biogeography of phytoplankton interact with external resource supply ratios to govern nutrient cycling and primary productivity. We find that all three nutrients can limit global primary productivity, and that the ratio of geochemical supply to biological demand of each nutrient in each ocean region determines the limiting nutrients, with nitrogen N fixation providing a mechanism for the cycles to interact. These results have important consequences for our understanding of biogeochemical cycles, ocean-atmosphere interactions, marine ecology, and the response of ocean ecosystems to climate change. Our work demonstrates the importance of resource ratios and suggests that future studies of the physiological and geochemical regulation of these ratios are indispensable to building accurate theories and future predictions of nutrient cycling and primary productivity.

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 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 Namib Desert primary productivity is driven by cryptic microbial community N-fixation

2018 ◽  
Vol 8 (1) ◽  
Author(s):  
Jean-Baptiste Ramond ◽  
Stephan Woodborne ◽  
Grant Hall ◽  
Mary Seely ◽  
Don A. Cowan
Keyword(s):  
Microbial Community ◽  
Primary Productivity ◽  
N Fixation ◽  
Namib Desert

scholarly journals Temporal variation in the biomass and nutrient status of Azolla filiculoides Lam. (Salviniaceae) in a small shallow dystrophic lake

2012 ◽  
Vol 23 (4) ◽  
pp. 368-375 ◽  
Author(s):  
Claudio Rossano Trindade Trindade ◽  
Edélti Faria Albertoni ◽  
Cleber Palma-Silva
Keyword(s):  
Temporal Variation ◽  
Primary Productivity ◽  
Tap Water ◽  
Rio Grande ◽  
Nutrient Status ◽  
N:P Ratio ◽  
N Fixation ◽  
Nitrogen And Phosphorus ◽  
Azolla Filiculoides ◽  
Dystrophic Lake

AIM: This study determined the temporal variation of the biomass and the concentrations of carbon, nitrogen and phosphorus in Azolla filiculoides Lam. in a small (0.5 ha) shallow dystrophic lake located in the city of Rio Grande (Rio Grande do Sul State, Brazil). METHOD: Sampling was conducted monthly between November 2000 and October 2001. The macrophytes were collected randomly in three replicates with a circular collector 0.3 m in diameter and subsequently washed with tap water and oven-dried at 60 ºC for determination of the dry weight and the nutrient status (i.e., carbon, nitrogen and phosphorus). Primary productivity was estimated by the variation in biomass among successive samples. RESULTS: A. filiculoides was present in the lake throughout the year and occupied between 50 and 80% of the surface area. The biomass values ranged from 34.2 g DW.m-2, recorded in May (autumn), to 170.9 g DW.m-2 in January (summer). The highest rate of primary productivity was 3.3 g DW.m-2.d-1, observed in June. The concentrations of carbon, nitrogen and phosphorus in the plant ranged between 403 and 551 g.kg-1, 13.4 and 25.7 g.kg-1 and 0.5 and 1.9 g.kg-1, respectively. The water N:P ratio ranged between 19:1 and 368:1. CONCLUSION: The coverage of the surface of the lake by A. filiculoides throughout the study period and the nutritional status of the plant demonstrate the importance of the cycling of nutrients by macrophytes in this aquatic environment. The higher N:P ratio in the water column, compared with other neighboring environments without macrophytes, shows that the enrichment of the lake may result from the biological N-fixation activity produced by A. filiculoides.

scholarly journals Nitrate Reducing and Denitrifying Bacteria in Oil/Brine Contaminated Soils

2020 ◽  
pp. 699-705
Author(s):  
Samer AbuBakr
Keyword(s):  
Crude Oil ◽  
Nitrogen Cycling ◽  
Contaminated Soils ◽  
Denitrifying Bacteria ◽  
Nitrite Reduction ◽  
Contaminated Sites ◽  
N2o Emissions ◽  
N Fixation ◽  
Soil Ecosystem ◽  
Available Nitrogen

Soil microorganisms are a fundamental part of biogeochemical cycling of nitrogen. Denitrification is an important component of nitrogen cycling, in which some microorganisms (e.g. denitrifying bacteria) use nitrate or nitrite as alternative electron acceptors. In fact, several studies have focused on various aspects of nitrogen cycling. Philippot et al. (2009) linked the distribution of the fraction of bacteria with the genetic capacity to reduce N2O to N2 to areas with low potential N2O emissions in a pasture. In addition, it was shown that a map of denitrification activity across a whole farm was reflected by maps displaying the community size and structure of a specific fraction of the denitrifyers at the site (Enwall et al., 2010). Since denitrification releases mineralized nitrogen in the soil ecosystem to the atmosphere, the balance between denitrification and N-fixation can determine the biologically available nitrogen for soils. Denitrification could be affected by soil ecosystem contaminants such as crude oil and brine as they may alter the abundance and species composition of denitrifying bacteria in predictable ways. For example, γ-Proteobacteria are known to increase in crude-oil contaminated sites and in fact, a wide diversity of γ-Proteobacteria including Pseudomonas and Vibrio species were shown to degrade hydrocarbons under nitrate reducing (NR) conditions (Rockne et al., 2000). Other studies showed that strains for several genera of γ-Proteobacteria have the ability to denitrify. In fact, it was shown that nitrate and nitrite reduction rates were increasingly inhibited at increasing NaCl concentrations when comparing treatment of fishery wastewaters. Bacterial diversity in brine-contaminated sites is expected to be less because of selection for salt-tolerant genera such as Bacillus and Pseudomonas.

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