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107 results for “Nitrogen fixation”
Post-fire Variability in Siberian Alder in Interior Alaska: Distribution Patterns, Nitrogen Fixation Rates, and Ecosystem Consequences VIII - Soils 2015
This data set was collected as a part of Brian Houseman's MS Thesis, Post-fire Variability in Siberian Alder in Interior Alaska: Distribution Patterns, Nitrogen Fixation Rates, and Ecosystem Consequences (December 2017). Data include soil characteristics (temperature, moisture, depth, N, C, P, and pH) that were measured in 2015. Data were collected on study plots established across two burn scars (2004 Boundary Fire and 1971 Wickersham Dome Fire) within the Yukon-Tanana Uplands ecoregion of interior Alaska.
Post-fire Variability in Siberian Alder in Interior Alaska: Distribution Patterns, Nitrogen Fixation Rates, and Ecosystem Consequences IX - Plant Identifications 2015
This data set was collected as a part of Brian Houseman's MS Thesis, Post-fire Variability in Siberian Alder in Interior Alaska: Distribution Patterns, Nitrogen Fixation Rates, and Ecosystem Consequences (December 2017). Data include plant voucher collections that were collected on study plots in 2015. Data were collected on study plots established across two burn scars (2004 Boundary Fire and 1971 Wickersham Dome Fire) within the Yukon-Tanana Uplands ecoregion of interior Alaska.
Post-fire Variability in Siberian Alder in Interior Alaska: Distribution Patterns, Nitrogen Fixation Rates, and Ecosystem Consequences X - Research Project Site Information 2014
This data set was collected as a part of Brian Houseman's MS Thesis, Post-fire Variability in Siberian Alder in Interior Alaska: Distribution Patterns, Nitrogen Fixation Rates, and Ecosystem Consequences (December 2017). Data include research site location information. Data were collected on study plots established across two burn scars (2004 Boundary Fire and 1971 Wickersham Dome Fire) within the Yukon-Tanana Uplands ecoregion of interior Alaska.
Raw data: High-throughput screening of soybean di-nitrogen fixation and seed nitrogen content using spectral sensing
<p>Symbiotic di-nitrogen fixation of grain legumes has a substantial impact on crop performance, harvest product quality, and nitrogen (N) balance of crop rotations, particularly under organic management regimes. In soybean breeding, selection for increased nitrogen fixation is desirable for improving seed protein content and N balance of cropping systems. However, the lack of high-throughput screening methods for direct measurement of N 2 fixation rates prohibits practical breeding efforts. Therefore, hyperspectral canopy reflectance measurement as a field-based phenotyping method was evaluated in three environments for indirect estimation of N fixation and uptake of soil nitrogen in a set of early maturity soybean genotypes exhibiting a wide range in seed protein content. Reflectance spectra were collected in repeated measurements during flowering and early seed filling stages. Subsequently, various spectral reflectance indices (SRIs) were calculated for characterizing nitrogen accumulation of individual genotypes. Moreover, prediction models for seed protein content as an end-of-season target trait were developed utilizing full spectral information in partial-least-square regression (PLSR) models. A number of N-related SRIs calculated from spectral reflectance data recorded at the beginning of the seed filling stage were significantly correlated to seed protein content. The best prediction of seed protein content, however, was achieved in PLSR models (validation R 2 =0.805 across all three environments). Environments lower in initial soil mineral N content appeared as more favorable selection sites in terms of prediction accuracy, because N fixation is not masked by soil N uptake in such environments. Hyperspectral reflectance data proved to be a valuable method for determining genetic variation in crop N accumulation, which might be implemented in high-throughput screening protocols for N fixation in plant breeding programs.</p>
Data and analyses for Perkowski et al. (2024) manuscript accepted to AoB Plants: "Symbiotic nitrogen fixation reduces belowground biomass carbon costs of nitrogen acquisition under low, but not high, nitrogen availability"
<p>This repository contains data and scripts for analyses and plots in Perkowski et al. (2024), titled "Symbiotic nitrogen fixation reduces belowground biomass carbon costs of nitrogen acquisition under low, but not high, nitrogen availability".</p> <p>v2.0 updates code and scripts per reviewer comments and is the final release prior to manuscript proofing.</p>
Nitrogen fixation responds to soil nitrogen at low but not high light in two invasive understory species
<p>Light and soil nitrogen availability can be strong controls of plant nitrogen (N) fixation, but data on how understory N-fixing plants respond to these drivers are limited despite their important role in ecosystem N cycling. Furthermore, ecosystem N cycling can be altered by the introduction of species with nutrient use patterns that differ from natives. We assessed how N fixation of two exotic, understory species responded to varying light and soil N environments. We sampled leaf tissue from <em>Mimosa pudica </em>L., <em>Desmodium triflorum</em> (L.) DC., and a non-fixing reference plant (<em>Axonopus</em>) growing in control and two N fertilization treatments under either N-fixing or non-N-fixing trees, which may alter local soil nutrient cycling, across a range of light conditions. We measured N fixation with <sup>15</sup>N isotope dilution, and ensured that N-fixing neighbor trees were in fact fixing N. All understory plants were wild-growing species not native to the study location. <em>Desmodium </em>and <em>Mimosa </em>acquired 82.6% and 71.6% of their nitrogen from fixation (%N<sub>dfa</sub>) in the control, compared to 66.8% and 58.1% in the +10 g N m<sup>−2</sup> y<sup>−1</sup> treatment and 73.1% and 64.7% in the +15 g N m<sup>−2</sup> y<sup>−1</sup> treatment. These subtle %N<sub>dfa</sub> differences across fertilization treatments were more apparent at low light availability and disappeared at high light availability. The amount of N fixed by neighboring trees did not influence %N<sub>dfa</sub> in the understory species. Our study shows some differences in N fixation across different nutrient environments at low light for two N-fixing species, though the changes were small, and both species derived most of their N from fixation. These findings imply that introduced N-fixing species could exacerbate ecosystem N enrichment, particularly under high soil N conditions</p>
Data from: Associative nitrogen fixation (ANF) in switchgrass (Panicum virgatum) across a nitrogen input gradient
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Data from: Rainfall events stimulate episodic associative nitrogen fixation in switchgrass
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Nitrogen Fixation Responses in Sphagnum fuscum to N-Additions to an Alberta Peatland, 2012-2015
Development of the oil sands has led to increasing atmospheric N deposition, with values as high as 17 kg N ha-1 yr-1; regional background levels <2 kg N ha-1 yr-1. Bogs, being ombrotrophic, may be especially susceptible to increasing N deposition. To examine responses to N deposition, over five years, we experimentally applied N (as NH4NO3) to a bog near Mariana Lakes, Alberta, at rates of 0, 5, 10, 15, 20, and 25 kg N ha-1 yr-1, plus controls (no water or N addition). We measured N2-fixation using the acetylene reduction technique between 2012 and 2015. All measurements were made between June and August. Mean acetylene reduction rates ranged from 2.2 mg m-2 da-1 (late June 2012) to 12.3 mg m-2 da-1 (late July 2014). Averaged across all measurement dates, rates were highest in the 5 kg N ha-1 yr-1 treatment, and decreased with increasing N loading. The acetylene reduction/N2 fixation response to N addition was described by a segmented linear regression, with rates increasing as N addition increased to 3.1 ± 1.5 kg N ha-1 yr-1 and decreasing with further increases in N addition. Water addition alone had no significant effect on N fixation rates on any of the measurement dates (p >= 0.79). While increasing N deposition may not substantively change total inputs of new N to bogs, the form on new N inputs shifts to inorganic N in deposition, rather than organic N produced by the microorganisms that are fixing N2.
Nitrogen Fixation Responses in Sphagnum Mosses to N-Additions to an Alberta Poor Fen, 2012-2015
Development of the oil sands has led to increasing atmospheric N deposition, with values as high as 17 kg N ha-1 yr-1; regional background levels <2 kg N ha-1 yr-1. To examine responses to N deposition, over five years, we experimentally applied N (as NH4NO3) to a poor fen near Mariana Lake, Alberta, at rates of 0, 5, 10, 15, 20, and 25 kg N ha-1 yr-1, plus controls (no water or N addition). Between June and August of each year, we measured N2-fixation using the acetylene reduction technique between 2012 and 2015Averaged across all measurement dates, whether described by a linear or segmented regression, N2-fixation rates decreased with increasing N addition. N2-fixation rates were not different between the water addition only treatments and the control treatments (p = 0.44). While increasing N deposition may not substantively change total inputs of new N to bogs, the form of new N inputs shifts to inorganic N in deposition, rather than organic N produced by the microorganisms that are fixing N2.
Co-occurrence of in-stream nitrogen fixation and denitrification across a nitrogen gradient in a western U.S. watershed, 2015 - 2016
This data was collected as part of the NSF CAREER Grant DEB 14-51919 to Amy Marcarelli to evaluate if nitrogen fixation and denitrification co-occur in streams across a gradient of nitrate concentrations. This data was collected during summer 2015 and 2016 in the Portneuf River watershed near Pocatello, ID. In summer 2015, rates of nitrogen fixation were only measured on rock substrate and denitrification only on sediment substrate. In summer 2016, both process rates were measured on both rock and sediment substrate to more accurately capture variation in rates.
Effects of stem canker disease on N fixation inputs by Alnus tenuifolia to early-successional floodplains in interior and south-central Alaska. I. Nitrogen fixation rates, leaf chemistry and soil chemistry.
This dataset contains data on nitrogen fixation rates, leaf chemistry, soil temperature and moisture, and soil chemistry on trees selected for studying disease-mediated declines in N-fixation inputs by Alnus tenuifolia to early-successional floodplains in interior and south-central Alaska
Nitrogen fixation, nodule respiration, and nodule Frankia identiy in alder growing in control, N-fertilized, and P-fertilized stands.
This data file includes data of simultaneous measurements of nitrogen fixation and nodule respiration in nodule clusters where Frankia identities were determined using molecular techniques from Alnus tenuifolia growing in replicate control, N-fertilized, and P-fertilized mid-successional stands along the Tanana River.
Murphy Dome: Nitrogen fixation rate by moss-associated cyanobacteria
This dataset contains the d15N, d13C, %N, %C or enriched samples, and natural abundance of d15N in the control samples. The data was collected in three blocks (A, B, and C) of adjacent black spruce and paper birch stands at Murphy Dome (access via Cache Creek road) in 2013, 2014 and 2015.
Aphid infestation differently affects the defences of nitrate-fed and nitrogenfixing Medicago truncatula and alters symbiotic nitrogen fixation
<p>Legumes can meet their nitrogen requirements through root nodule symbiosis, which could also trigger plant systemic resistance against pests. The pea aphid Acyrthosiphon pisum, a legume pest, can harbour different facultative symbionts (FS) influencing various traits of their hosts. It is, therefore, worth determining if and how the symbionts of the plant and the aphid modulate their interaction. We used different pea aphid lines without FS or with a single one (Hamiltonella defensa, Regiella insecticola, Serratia symbiotica) to infest Medicago truncatula plants inoculated with Sinorhizobium meliloti (symbiotic nitrogen fixation (SNF)) or supplemented with nitrate (non-inoculated (NI)). The growth of SNF and NI plants was reduced by aphid infestation, while aphid weight (but not survival) was lowered on SNF compared to NI plants. Aphids strongly affected the plant nitrogen fixation depending on their symbiotic status, suggesting indirect relationships between aphid- and plant-associated microbes. Finally, all aphid lines triggered expression of Pathogenesis-Related Protein 1 (PR1) and Proteinase Inhibitor (PI), respective marker for salicylic and jasmonic pathways, in SNF plants, compared to only PR1 in NI plants. We demonstrate that the plant symbiotic status influences plant–aphid interactions while that of the aphid can modulate the amplitude of the plant's defence response.</p>
Data from: Environmental change alters nitrogen fixation rates and microbial parameters in a subarctic biological crust
<p>Together, Biological Soil Crust (BSC) and other cryptogamic groundcovers can contribute up to half of the global nitrogen (N) fixation. BSC also stabilizes the soil (reducing erosion and dust emissions), fixes carbon (C), retains moisture, and acts as a hotspot of microbial diversity and activity. Much of the knowledge about how climate change is affecting the composition and functioning of BSC comes from hot arid and semiarid regions. The comparatively smaller body of research on BSC from cold and mesic environments has been primarily observational, for example along chronosequences after a glacier retreat. Few studies have experimentally investigated the effects of the environment on BSC from high latitudes. Such experiments allow unraveling of relationships at a resolution that can only be achieved by controlling for confounding factors. We measured short-term (2-4 days) responses of a liverwort-based (Anthelia juratzkana) BSC from the south of Iceland to a range of temperature, moisture and light conditions. Warming increased N fixation rates, especially when moisture was at a saturation level, and only when light was not limiting. A correlation analysis suggests that increases in N fixation rates were linked to cyanobacterial abundance on the BSC surface and to the rates of their metabolic activity. Warming and moisture changes also induced compositional and structural modification of the bacterial community, with consequences at the functional level. In contrast to many observations on BSC from hot drylands, the BSC from our cold and mesic study site is more limited by low temperature and light than by moisture. Our findings show possible ways in which BSC from cold and mesic ecosystems can respond to short-term manifestations of climate change, such as increasingly frequent heat waves.</p>
Data from: Disentangling the variability of symbiotic nitrogen fixation rate and the controlling factors
<p>Symbiotic nitrogen (N) fixation (SNF), replenishing bioavailable N for terrestrial ecosystems, exerts decisive roles in N cycling and gross primary production. Nevertheless, it remains unclear what determines the variability of SNF rate, which retards the accurate prediction for global N fixation in earth system models. This study synthesized 1230 isotopic observations to elucidate the governing factors underlying the variations of SNF rate. The SNF rates varied significantly from 3.69 to 12.54 g N m<sup>-2</sup> yr<sup>-1</sup> across host plant taxa. The traits of host plant (e.g., biomass characteristics and taxa) far outweighed soil properties and climatic factors in explaining the variations of SNF rate, accounting for 79.0% of total relative importance. Furthermore, annual SNF yield contributed to more than half of N uptake for host plants, which was consistent across different ecosystem types. This study highlights that the biotic factors, especially host plant traits (e.g., biomass characteristics and taxa), play overriding roles in determining SNF rate compared with soil properties. The suite of parameters for SNF lend support to improve N fixation module in earth system models that can provide more confidence in predicting bioavailable N changes in terrestrial ecosystems.</p>
Data from: Dissolved nitrogen uptake versus nitrogen fixation: Mode of nitrogen acquisition affects stable isotope signatures of a diazotrophic cyanobacterium and its grazer
<p>Field studies suggest that changes in the stable isotope ratios of phytoplankton communities can be used to track changes in the utilization of different nitrogen sources, i.e., to detect shifts from dissolved inorganic nitrogen (DIN) uptake to atmospheric nitrogen (N<sub>2</sub>) fixation by diazotrophic cyanobacteria as an indication of nitrogen limitation. We explored changes in the stable isotope signature of the diazotrophic cyanobacterium <em>Trichormus variabilis</em> in response to increasing nitrate (NO<sub>3</sub><sup>-</sup>) concentrations (0 to 170 mg L<sup>-1</sup>) under controlled laboratory conditions. In addition, we explored the influence of nitrogen utilization at the primary producer level on trophic fractionation by studying potential changes in isotope ratios in the freshwater model <em>Daphnia magna</em> feeding on the differently grown cyanobacteria. We show that <em>δ</em><sup>15</sup>N values of the cyanobacterium increase asymptotically with DIN availability, from -0.7 ‰ in the absence of DIN (suggesting N<sub>2</sub> fixation) to 2.9 ‰ at the highest DIN concentration (exclusive DIN uptake). In contrast, <em>δ</em><sup>13</sup>C values of the cyanobacterium did not show a clear relationship with DIN availability. The stable isotope ratios of the consumer reflected those of the differently grown cyanobacteria but also revealed significant trophic fractionation in response to nitrogen utilization at the primary producer level. Nitrogen isotope turnover rates of <em>Daphnia</em> were highest in the absence of DIN as a consequence of N<sub>2</sub> fixation and resulting depletion in <sup>15</sup>N at the primary producer level. Our results highlight the potential of stable isotopes to assess nitrogen limitation and to explore diazotrophy in aquatic food webs.</p>
Data from: More diverse rhizobial communities can lead to higher symbiotic nitrogen fixation rates, even in nitrogen-rich soils
<p>Symbiotic nitrogen fixation (SNF) by legumes and their rhizobial partners is one of the most important sources of bioavailable nitrogen to terrestrial ecosystems. While most work on the regulation of SNF has focused on abiotic drivers such as light, water, and soil nutrients, the diversity of rhizobia with which an individual legume partners may play an important but under-recognized role in regulating nitrogen inputs from SNF. By experimentally manipulating the diversity of rhizobia available to legumes, we demonstrate that rhizobial diversity can increase average SNF rates by more than 90%, and that high rhizobial diversity can induce increased SNF even under conditions of high soil N fertilization. However, the effects of rhizobial diversity, the conditions under which diversity effects were strongest, and the likely mechanisms driving these diversity effects differed between the two legume species we assessed. These results provide evidence that biodiversity-ecosystem function relationships can occur at scales of an individual plant, and that the effects of rhizobial diversity may be as important as long-established abiotic factors, such as nitrogen availability, in driving terrestrial nitrogen inputs via SNF.</p>
Biological nitrogen fixation in cropland
<p>Methods are documented in the README.md of the source code repository:</p> <p><a href="https://doi.org/10.5281/zenodo.7133336">https://doi.org/10.5281/zenodo.7133336</a></p> <p>The version number of this dataset corresponds to the version number of the source code.</p>
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