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33 results for “nitrogen uptake”
Organic and Inorganic Nitrogen Uptake by Sarracenia Purpurea at Harvard Forest and Fort Albany ON 2007
The nitrogen-limited carnivorous pitcher plant Sarracenia purpurea and its associated detritus-based food web is a model system for studying plant nutrient dynamics. We tested if S. purpurea can directly take up intact amino acids and compared uptake of organic and inorganic forms of nitrogen (N) across a gradient of N deposition. At sites in Canada and the United States, individual pitchers with complete or incomplete food webs were fed U-13C-15N-glycine, U-13C-15N-phenylalanine and 15NH415NO3 individually and in mixture. Plants took up intact amino acids. Acquisition of each N form provided in isolation exceeded uptake of the same form in mixture. At the high deposition site, uptake of 15N from amino acids was higher than uptake of 15N from inorganic nitrogen. At the low deposition site, uptake of 15N from all three forms of N were similar. Completeness of the associated food web had no effect on 15N uptake. By taking up intact amino acids, Sarracenia purpurea can short-circuit the inorganic N cycle, thus minimizing potential bottlenecks in N availability that result from the plant’s reliance for nitrogen mineralization on a seasonally reconstructed food web operating on infrequent and irregular prey capture.
Rapid root to leaf uptake of inorganic and amino acid nitrogen in three dryland plant species.
Our aim was to quantify inorganic and organic nitrogen (N) uptake and compare short-term nutrient acquisition patterns among three dryland plant species: Bouteloua eriopoda, Achnatherum hymenoides, and Gutierrezia sarothrae collected from a mixed grassland community in the Northern Chihuahuan Desert to better understand how asynchronous resource availability may influence biotic interactions and nutrient retention in these ecosystems. We collected living plants from two locations within the Sevilleta National Wildlife Refuge and transplanted them into pots maintained in the greenhouse with supplemental light and water for two months. We then conducted a greenhouse experiment using these species to compare nutrient uptake of 15N-labeled ammonium (NH4+), nitrate (NO3-), and glutamate (an amino acid) over 12 to 48 hours. Our study examined three main questions: (1) How rapidly do these dryland plants take up available soil N?, (2) Does leaf uptake differ among inorganic and amino acid N forms?, and (3) Do plant species differ in the speed or form of short-term N uptake?. In the greenhouse, we applied one of three isotopic 15N tracers directly to plant roots and quantified N uptake and recovery in leaves after 12, 24, and 48 hours. We found that plants took up inorganic and amino acid N to leaves as rapidly as 12 h following application, and N uptake more than doubled between 24 and 48 h. Inorganic N uptake was 3-4x higher than organic N uptake in all three species, and plants took up ammonium and nitrate at 2-3x faster rates than glutamate. On average, B. eriopoda had higher inorganic N recovery and uptake speeds, while G. sarothrae had the highest organic N uptake over time. A. hymenoides root to leaf uptake was ~50% lower than the other two species after 48 h. Plants showed similar patterns of short-term foliar uptake and recovery indicating a lack of niche partitioning by N form among the three dryland species measured. Our results suggest that soil inorganic N, par
Lotic Intersite Nitrogen eXperiment II (LINX II): a cross-site study of the effects of anthropogenic land use change on nitrate uptake and retention in 72 streams across 8 different biomes (2003 – 2006).
The LINX II (Lotic Intersite Nitrogen eXperiment) project was designed to quantify the rates and mechanisms of nitrate retention in streams using stable isotope tracer additions. The study encompassed 72 stream reaches spread across 8 North American biomes. Within each biome, 9 streams were selected in three watershed land-use categories: 3 reference, 3 agricultural, and 3 urbanized. The core of the study was a 24-hour release of 15N- labeled nitrate. Prior to the isotope addition, physical, chemical and biological characteristics of the stream were measured. The measurements included, but were not limited to, dissolved nutrient concentrations, dissolved conservative tracer additions (to quantify hydraulic and hyporheic retention, velocity and discharge), standing stocks of primary uptake biota (including suspended and benthic particulate materials) as well as channel dimensions, photosynthetically active radiation, and water temperature. During the isotope release, whole stream rates of ecosystem metabolism were quantified (including quantification of re-aeration coefficients using tracer gas additions), and concentrations of 15N-labeled NO3, NH4, N2 and N2O were measured. Immediately following the isotope addition, 15N uptake by aquatic organisms was quantified by sampling biomass components on the stream bed. The data generated from these 72 stream reaches were used to develop a stream nitrogen retention model for each biome, which was expanded to entire drainage networks to predict nitrogen fluxes. The LINX II study demonstrated how biotic uptake of nitrate and denitrification increased with increasing nitrate concentrations. However, the efficiency of total uptake and denitrification actually declined with increasing nitrate concentrations (such as those seen on agricultural or urbanized streams), yielding higher rates of dissolved nitrogen exports downstream. The datasets presented here consist of the primary data collected by the LINX II study participants.
Post-fire succession in 1994 Hajdukovich Creek Burn: in-situ measurements of aspen and spruce inorganic nitrogen uptake rates
This dataset contains in-situ measurements of inorganic nitrogen uptake rates in aspen and spruce saplings regenerating in one severely and one lightly burned site in the 1994 Hajdukovich Creek burn.
Climate Change Across Seasons Experiment (CCASE) at the Hubbard Brook Experimental Root Nitrogen Uptake Capacity
Fine root nitrogen uptake capacity was measured on excised roots prior to experimental treatment in 2013 and throughout the growing seasons of 2014 and 2015 on all Climate Change Across Seasons Experiment (CCASE) plots. Reference (or control) plots are shared with the collaborating Northern Forest DroughtNet experiment. There are six plots total (each 11 x 14m). Two are warmed 5 degrees C throughout the growing season (Plots 3 and 4). Two others are warmed 5 degrees C in the growing season and have snow removed during winter to induce soil freeze/thaw cycles (Plots 5 and 6). Four kilometers (2.5 mi) of heating cable are buried in the soil to warm these four plots. Two additional plots serve as controls for our experiment (Plots 1 and 2). Analysis and results from these data are presented in Sanders-DeMott 2018. These data were gathered as part of the Hubbard Brook Ecosystem Study (HBES). The HBES is a collaborative effort at the Hubbard Brook Experimental Forest, which is operated and maintained by the USDA Forest Service, Northern Research Station. Sanders-DeMott, R., Sorensen, P.O., Reinmann, A.B. et al. Growing season warming and winter freeze–thaw cycles reduce root nitrogen uptake capacity and increase soil solution nitrogen in a northern forest ecosystem. Biogeochemistry 137, 337–349 (2018). https://doi.org/10.1007/s10533-018-0422-5
SBC LTER: Reef: Kelp Nitrogen uptake in Carpinteria and Mohawk kelp forests, 2016-2017
A large on-going time-series monthly water samples have been taken at 1m, 5 m and 10 m depth from the offshore edge of five kelp forests near Santa Barbara, CA, USA (Arroyo Burro, Arroyo Quemado, Carpinteria, Mohawk, Naples). See dataset: http://sbc.lternet.edu/cgi-bin/showDataset.cgi?docid=knb-lter-sbc.10. Two datasets are presented here. One is a field study conducted in two of the sites (Mohawk or Carpinteria) to test the N uptake of giant kelp (Macrocystis pyrifera) and phytoplankton from May 2016 to October 2017. In situ rates of urea, ammonium and nitrate uptake by giant kelp blades and phytoplankton, which were enclosed together within polyethylene blade bags, from the surface canopy of Mohawk or Carpinteria kelp forests. The second dataset has the results of laboratory experiments for testing the direct uptake of urea by whole blades and natural phytoplankton communities entrained in surface canopy waters.
Host-derived viral transporter protein for nitrogen uptake in infected marine phytoplankton
<p>Dataset for the article "Host-derived viral transporter protein for nitrogen uptake in infected marine phytoplankton", Monier et al.</p> <p>Data for all phylogenetic tree reconstructions (raw and masked protein sequence alignments in fasta format, tree file in newick format) and placement file (jplace format) of two environmental sequences are available.</p> <p>Data for all assay experiments are available: ammonium and urea assays, Omnilog phenotype screening (Nitrogen substrates).</p>
Figure 1 in Relative uptake of organic and inorganic nitrogen by common weed species
Figure 1. Estimated intact amino acid uptake (root) and translocation (shoot) plotted against the excess 15N (atom percent excess 15N [15N APE]) found in each respective tissue type (amino acid 15N treatment only) for each weed species. Whole amino acid uptake and translocation were calculated by dividing the observed 15N:13C in plant tissue with the measured 15N:13C in the dual-labeled fertilizer. Data are means ± SE (n = 5). See Table 1 for list of full species names.
Figure 2 in Relative uptake of organic and inorganic nitrogen by common weed species
Figure 2. Canonical plot displaying the results of a linear discriminant analysis evaluating patterns in 15N uptake by species (Wilks's lambda = 0.0157, F(42, 83) = 2.8227, P <0.0001). The first two canonical axes were the most explanatory, accounting for 66.9% and 19.7% of the model variation. Species multivariate means (þ symbols) are surrounded by 95% confidence ellipses. Weighted biplots of N form by tissue atom percent excess 15N (15N APE) values are emanating from the grand mean of the data set, and their length and direction indicate the relative strength of their correlation with the first two axes. See Table 1 for list of full species names.
SBC LTER: Reef: Surge uptake capability in Macrocystis pyrifera in response to pulses of three different forms of nitrogen
This data describes the capacity of the giant kelp, Macrocystis pyrifera to exhibit surge uptake of three different forms of nitrogen in whole-blade incubation experiments done in spring and summer 2019. The data is contained in 2 tables: 1) uptake rates of 15N labeled nitrate, ammonium, and urea by blades exposed to pulses of nitrogen for periods lasting 1, 5, 15 and 45 min, 2) uptake rates of 15N labeled nitrate, ammonium, and urea for specific time intervals of pulsed nitrogen (e.g., 0-1 min, 1-5 min, 5-15 min and 15-45 min).
A non‐steady state model based on dual nitrogen and oxygen isotopes to constrain moss nitrate uptake and reduction
<p><span><span>Epilithic mosses are early colonizers of the terrestrial biosphere, constitute a special ecosystem regulating rock-atmosphere interactions, and may be more restricted in their nitrogen (N) supply than other mosses.<sup> </sup>Terrestrial mosses can take up nitrate (NO<sub>3</sub><sup>-</sup>), a major form of bioavailable N, from soil substrates. However, the importance of substrate NO<sub>3</sub><sup>-</sup> relative to atmospheric NO<sub>3</sub><sup>-</sup> remains unclear in moss NO<sub>3</sub><sup>-</sup> utilization. This has prevented the understanding of moss NO<sub>3</sub><sup>-</sup> dynamics and its responses to environmental N loadings. Here we investigated the monthly concentrations, δ<sup>15</sup>N, and δ<sup>18</sup>O of NO<sub>3</sub><sup>-</sup> in four epilithic moss species from August, 2006 to August, 2007 in Guiyang, southwestern China. We developed a non-steady state isotope mass-balance model based on dual N and O isotopes to evaluate fractional contributions of atmospheric NO<sub>3</sub><sup>-</sup> (<i>Ф</i><sub>atm</sub>) and soil NO<sub>3</sub><sup>-</sup> (<i>Ф</i><sub>soil</sub>), moss NO<sub>3</sub><sup>-</sup> uptake flux (<i>F</i><sub>influx</sub>), moss NO<sub>3</sub><sup>-</sup> reduction flux (<i>F</i><sub>reduction</sub>), and the percentage of NO<sub>3</sub><sup>-</sup> reduction in total NO<sub>3</sub><sup>-</sup> uptake of mosses (expressed as <i>f</i><sub>reduced</sub>). Monthly <i>Ф</i><sub>soil</sub> values averaged 53 ± 13% and monthly <i>f</i><sub>reduced</sub> values averaged 50 ± 35%. Both monthly<i> F</i><sub>reduction</sub> and <i>f</i><sub>reduced</sub> values increased with monthly <i>F</i><sub>influx</sub> values, particularly when <i>Ф</i><sub>soil</sub> values were higher than <i>Ф</i><sub>atm</sub> values. However, the amount of annual NO<sub>3</sub><sup>-</sup> reduction (219.7 ± 30.5 μg-N/g, dw) accounted for only 1.0 ± 0.2% in bulk N of mosses. We conclude that half of NO<sub>3</sub><sup>-</sup> in epilithic mosses is derived from soil NO<sub>3</sub><sup>-</sup> and that NO<sub>3</sub><sup>-</sup> uptake from soil induces moss NO<sub>3</sub><sup>-</sup> reduction, but the total NO<sub>3</sub><sup>-</sup> assimilation contributed a low fraction to total N of study mosses. These findings are important for understanding N sources and dynamics in terrestrial mosses.</span></span></p>
Data and code for: Suppression of nitrogen deposition on global forest soil CH4 uptake depends on nitrogen status
<p>Methane (CH4) is the second most important atmospheric greenhouse gas (GHG) and forest soils are a significant sink for atmospheric CH4. Uptake of CH4 by global forest soils is affected by nitrogen (N) deposition; clarifying the effect of N deposition helps to reduce uncertainties of the global CH4 budget. However, it remains an unsolved puzzle why N input stimulates soil CH4 flux (RCH4) in some forests while suppressing it in others. Combining previous findings and data from N addition experiments conducted in global forests, we proposed and tested a “stimulating-suppressing-weakened effect” (“three stages”) hypothesis on the changing responses of RCH4 to N input. Specifically, we calculated the response factors (f) of RCH4 to N input for N-limited and N-saturated forests across biomes; the phased changes in f values supported our hypothesis. We also estimated the global forest soil CH4 uptake budget to be approximately 11.2 Tg yr–1. CH4 uptake hotspots were located predominantly in temperate forests. Furthermore, we quantified that current level of N deposition reduced global forest soil CH4 uptake by ~3%. This suppression effect was more pronounced in temperate forests than in tropical or boreal forests, likely due to differences in N status. The proposed “three stages” hypothesis in this study generalizes the diverse effects of N input on RCH4, which could help improve experimental design. Additionally, our findings imply that by regulating N pollution and reducing N deposition, soil CH4 uptake can be significantly increased in the N-saturated forests in tropical and temperate biomes.</p> <p>Specifically, Data Set S1 (CH4_exp dataset in main text) was used to derive the response factors of soil CH4 flux to N input in global forests; Data Set S2 (CH4_obs dataset in main text) was used to estimate the soil CH4 fluxes in global forests; Data Sets S3–S7 were used to classify the N-limited and N-saturated forests on global level; Data Set S8 contains environmental factors (MAT, MAP, soil texture, etc.) for global estimations on grid level; Data Set S9 contains global forest soil CH4 budgets reported in previous studies. The data analysis process and produced figures can be replicated with the uploaded R script (Code S1).</p>
Tree water uptake enhances nitrogen acquisition in a fertilized boreal forest – but not under nitrogen poor conditions
<p><span>Understanding how plant water uptake interacts with acquisition of soil nitrogen (N) and other nutrients is fundamental for predicting plant responses to a changing environment, but it is an area where models disagree.</span></p> <p><span>We present a novel isotopic labelling approach which reveals spatial patterns of water and N uptake, and their interaction, by trees. The stable isotopes <sup>15</sup>N and <sup>2</sup>H were applied to a small area of the forest floor in stands with high and low soil N availability. Uptake by surrounding trees was measured. The sensitivity of N acquisition to water uptake was quantified by statistical modelling.</span></p> <p><span>Trees in the high-N stand acquired twice as much <sup>15</sup>N as in the low-N stand and around half of their N uptake was dependent on water uptake (<sup>2</sup>H enrichment). In contrast, in the low-N stand there was no positive effect of water uptake on N uptake. </span></p> <p><span>We conclude that tree N acquisition was only marginally dependent on water flux toward the root surface under low N conditions but under high-N conditions, the water-associated N uptake was substantial. The results suggest a fundamental shift in N acquisition strategy under high-N conditions. </span></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>
Drought intensity alters productivity, carbon allocation, and plant nitrogen uptake in fast versus slow grassland communities
<p><span>Grasslands face more frequent and extreme droughts, yet their responses to increasing drought intensity are poorly understood. Increasing drought intensity likely triggers abrupt shifts (thresholds) in grassland ecosystem functioning which can implicate recovery trajectories. </span></p> <p><span>Here, we determined how drought intensity affects plant productivity, and plant-soil carbon (C) and nitrogen (N) cycling. We exposed model grassland plant communities with contrasting resource acquisition strategies (a fast- vs a slow-strategy plant community), to a gradient of drought intensity. The drought gradient ranged from well-watered to severely water-limited conditions. We identified thresholds of plant community productivity (above-ground biomass) at peak drought and two months after re-wetting, and measured net ecosystem exchange and ecosystem respiration of carbon throughout the drought and recovery phases. At peak drought and one week after re-wetting, we traced recently acquired C from plants to the soil and into microbial biomass and fatty acids using <sup>13</sup>C pulse labelling, and measured plant and soil N. </span></p> <p><span>At peak drought, slow-strategy plant communities were more drought resistant than fast-strategy communities, as the threshold in plant productivity occurred at a higher drought intensity for the slow- than the fast-strategy community. Shortly after re-wetting, microbial uptake of recent plant-assimilated C increased with increasing past drought intensity, coinciding with an increase in soil N availability and leaf N. Threshold responses to drought intensity at peak drought translated into non-linear recovery responses, with greater compensatory growth in the fast-strategy community. At peak drought, increasing drought intensity reduced C uptake and increased relative C partitioning to leaves and microbial biomass. Upon re-wetting, plant community strategy mediated drought intensity effects on plant and soil C and N dynamics and plant recovery trajectories. The fast strategy community recovered quickly, with higher leaf N than the slow community, while the slow community increased C allocation to microbial biomass. </span></p> <p><strong><span>Synthesis:</span></strong><span> Our findings highlight that C and N dynamics in the plant-soil system display non-linear responses to increasing drought intensity both during and after drought, which has implications for trajectories of plant community recovery. </span></p>
Independent and differential effects of arbuscular mycorrhizal fungal composition and plant pathogens on plant traits and nitrogen uptake
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Drought intensity alters productivity, carbon allocation, and plant nitrogen uptake in fast versus slow grassland communities
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A non‐steady state model based on dual nitrogen and oxygen isotopes to constrain moss nitrate uptake and reduction
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Tree water uptake enhances nitrogen acquisition in a fertilized boreal forest – but not under nitrogen poor conditions
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Microbial nitrogen: Schizachyrium scoparium Nutrient Uptake Profiles
The objective of this experiment is to determine the distances over which Schizachyrium scoparium can reduce available soil N. This experiment is being conducted in field B, outside the fenced area of the microplots. Each experimental unit consists of a circular plot of 3 meters diameter, at the center of which there is a Schizachyrium scoparium plant. Two treatments are being tested: 1 (=A). All the vegetation around the central S. scoparium was killed with roundup at a rate of 2.04 g/m2 (1g of Isopropylamine salt of N (phosphonomethyl ) Glycine ). Spraying was repeated at the same rate as needed (Yearly folder). A plastic barrier, 80 cm high, was placed around each Schizachyrium scoparium plant to protect it from any drift that might occur. The area sprayed is the circle with 2 m radius around the central plant. 2 (=B). The vegetation around S. scoparium is left intact. Each treatment is replicated 5 times. The two treatments were randomly assigned to the 10 plots of the experiment. The plot layout is: Plot # Treatment 1 2 2 1 3 2 4 2 5 1 6 1 7 1 8 2 9 2 10 1 Soil samples were taken several times and the amount of ammonium and nitrate were determined at the lab. Soil samples were also taken once for mineralization rate, microbial biomass and total carbon determination. When plants reached maturity, they were harvested and dried for dry matter determination, then ground for tissue nitrogen determination. For an additional list of treatments see the treatment layouts in file trmte38.
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