Find research datasets worth reusing
Search datasets from major research repositories and use ShareScore to quickly assess how well each record supports discovery, access, and reuse.
34
datasets available to search
ShareScore release 0.9.0
Dataset results
34 results for “nitrogen fluxes”
Vertical fluxes of particulate carbon, nitrogen and phosphorus from a sediment trap deployed west of Palmer Station, Antarctica at a depth of 170 meters, 1992-2019.
Particulate organic matter is exported from the upper ocean euphotic zone in the form of large sinking particles and as dissolved material. Particle fluxes to depth link the surface and mesopelagic realm and supply food to the benthos. Sedimentation flux is typically measured with sediment traps of various designs. Palmer LTER has deployed a time-series trap near 64.5degrees S, 66.0degrees W since late 1992. The trap is moored in 300 m depth and collects sinking particles at 150 m. Deployments and analyses were performed by David Karl, University of Hawaii until 2002 when Hugh Ducklow took over the sediment trap operations.Sedimentation at the PAL site of the West Antarctic Peninsula demonstrates extreme seasonality, with a well-defined pulse in the Austral summer following sea ice retreat. Daily sedimentation rates during the summer flux event are among the highest recorded globally. During the Austral winter when the ocean is covered by sea ice and shrouded in darkness, fluxes are among the lowest observed anywhere. Sedimentation rates at PAL typically vary by 4 orders of magnitude. There is also order of magnitude variability in the total annual flux (area under the curve).
Seasonal N dynamics and fluxes of nitrogen in leachate and runoff from experimental rainfalls on fertilized and unfertilized lawns in Baltimore County, Maryland
The aim of this research was to examine the spatial and temporal variation in export control points of nitrogen on residential lawns (locations prone to mobilizing nitrogen during a rain event) and to examine if previously measured hydrobiogeochemical properties were predictive of N mobilization in lawns. This data set contains measurements of saturated infiltration rates, sorptivity, soil moisture, soil organic matter, bulk density, pH, soil nitrate, soil ammonium, N2O, N2 and CO2 fluxes from soil cores, nitrogen mineralization rates and fluxes of N in runoff and leachate from fertilized and unfertilized residential and institutional lawns. Study lawns were located at homes of people who agreed to volunteer their lawn for the study from a door knocking campaign. Four sampling houses were located in an exurban neighborhood in Baisman Run. Five sampling houses were located in a suburban neighborhood in Dead Run. Two sampling locations on institutional lawns were located at University of Maryland Baltimore County. At the exurban study houses and institutional lawns sites, we identified one hillslope to conduct sampling on. At the Dead Run houses we identified one hillslope on the front yard and one in the backyard as there were distinct locations that were not present in the exurban neighborhood. Locations within the yards for sampling were selected based on sampling conducted in October 2017. Locations were grouped into four categories based on have either high or low potential denitrification rates and high or low saturated infiltration rates (n=48). These locations were also distributed across yard types (exurban, suburban or institutional), fertilizer treatments, and hillslope location (top or bottom of hillslope). At each sampling location we ran a Cornell Sprinkle Infiltrometer to generate an experimental rainfall during which we collected runoff and leachate to quantity N flux. We also measure sorptivity and saturated infiltration rates. Volumetric water conten
Modeled dry deposition flux of nitrogen (NO) in central Arizona, USA (1998)
The role of urban vegetation on NOx-derived dry deposition fluxes was investigated for the arid Phoenix (Arizona, USA) metropolitan area using the Community Multiscale Air Quality Model (CMAQ) (9-13 June 1998). A new land cover classification and updated land cover data were introduced in the model to account for spatial extent and heterogeneity of urban land cover. Adjustments were made in the deposition velocity calculations to consider the adaptation of local plants to the environmental conditions of Central Arizona. According to the simulations 25 % of the NOx derived dry deposition fluxes in the urban area were deposited on vegetation. When urban vegetation was excluded from the simulations NO2 deposition was reduced by 57 % because of the significantly lower deposition velocities of impervious compared to vegetated surfaces; nitric acid deposition was relatively unchanged. Using a diagnostic model with input data from urban air quality monitoring sites, hourly NO and NO2 dry N deposition fluxes were simulated for the entire year 1998 to ~6 kg ha-1 yr-1. Dry deposition declined during the summer months, due to lower pollutant concentrations and temperature-induced closure of the plant stomata during afternoon hours.
Modeled dry deposition flux of nitrogen dioxide (NO2) in central Arizona, USA (1998)
The role of urban vegetation on NOx-derived dry deposition fluxes was investigated for the arid Phoenix (Arizona, USA) metropolitan area using the Community Multiscale Air Quality Model (CMAQ) (9-13 June 1998). A new land cover classification and updated land cover data were introduced in the model to account for spatial extent and heterogeneity of urban land cover. Adjustments were made in the deposition velocity calculations to consider the adaptation of local plants to the environmental conditions of Central Arizona. According to the simulations 25 % of the NOx derived dry deposition fluxes in the urban area were deposited on vegetation. When urban vegetation was excluded from the simulations NO2 deposition was reduced by 57 % because of the significantly lower deposition velocities of impervious compared to vegetated surfaces; nitric acid deposition was relatively unchanged. Using a diagnostic model with input data from urban air quality monitoring sites, hourly NO and NO2 dry N deposition fluxes were simulated for the entire year 1998 to ~6 kg ha-1 yr-1. Dry deposition declined during the summer months, due to lower pollutant concentrations and temperature-induced closure of the plant stomata during afternoon hours.
Modeled dry deposition flux of nitrogen (HNO3) in central Arizona, USA (1998)
The role of urban vegetation on NOx-derived dry deposition fluxes was investigated for the arid Phoenix (Arizona, USA) metropolitan area using the Community Multiscale Air Quality Model (CMAQ) (9-13 June 1998). A new land cover classification and updated land cover data were introduced in the model to account for spatial extent and heterogeneity of urban land cover. Adjustments were made in the deposition velocity calculations to consider the adaptation of local plants to the environmental conditions of Central Arizona. According to the simulations 25 % of the NOx derived dry deposition fluxes in the urban area were deposited on vegetation. When urban vegetation was excluded from the simulations NO2 deposition was reduced by 57 % because of the significantly lower deposition velocities of impervious compared to vegetated surfaces; nitric acid deposition was relatively unchanged. Using a diagnostic model with input data from urban air quality monitoring sites, hourly NO and NO2 dry N deposition fluxes were simulated for the entire year 1998 to ~6 kg ha-1 yr-1. Dry deposition declined during the summer months, due to lower pollutant concentrations and temperature-induced closure of the plant stomata during afternoon hours.
Modeled dry deposition flux of total nitrogen in central Arizona, USA (1998)
The role of urban vegetation on NOx-derived dry deposition fluxes was investigated for the arid Phoenix (Arizona, USA) metropolitan area using the Community Multiscale Air Quality Model (CMAQ) (9-13 June 1998). A new land cover classification and updated land cover data were introduced in the model to account for spatial extent and heterogeneity of urban land cover. Adjustments were made in the deposition velocity calculations to consider the adaptation of local plants to the environmental conditions of Central Arizona. According to the simulations 25 % of the NOx derived dry deposition fluxes in the urban area were deposited on vegetation. When urban vegetation was excluded from the simulations NO2 deposition was reduced by 57 % because of the significantly lower deposition velocities of impervious compared to vegetated surfaces; nitric acid deposition was relatively unchanged. Using a diagnostic model with input data from urban air quality monitoring sites, hourly NO and NO2 dry N deposition fluxes were simulated for the entire year 1998 to ~6 kg ha-1 yr-1. Dry deposition declined during the summer months, due to lower pollutant concentrations and temperature-induced closure of the plant stomata during afternoon hours.
Tracegas fluxes in forests and old fields under enhanced nitrogen regimes at the Kellogg Biological Station, Hickory Corners, MI (2001 to 2020)
Dataset Abstract 10 m2 plots in the old field and forest ecosystems were fertilized with 2 rates of nitrogen. N2O, CO2 and CH4 measurements were made with a static chamber method original data source http://lter.kbs.msu.edu/datasets/53
Reactive nitrogen fluxes over peatland (Bourtanger Moor) and forest (Bavarian Forest National Park) using micrometeorological measurement techniques
<p>Within the framework of the research projects NITROSPHERE and FORESTFLUX, field campaigns were carried out to investigate the biosphere-atmosphere exchange of reactive nitrogen compounds. We applied novel fast-response instruments in eddy-covariance setups for continuous determination of surface ammonia (NH<sub>3</sub>) and total reactive nitrogen (<span class="math-tex">\(\Sigma\)</span>N<sub>r</sub>) fluxes using two different analytical devices. While high-frequency measurements of ammonia were measured with a quantum cascade laser absorption spectrometer (QCL), a custom-built converter called TRANC coupled to a chemiluminescence detector was used for the determination of total reactive nitrogen. High-resolution data of surface-atmosphere fluxes of reactive compounds are still scarce, but highly desired for testing and validating local inferential and larger scale models. We provide access to campaign data including concentrations, fluxes and ancillary measurements of meteorological data. Campaigns were conducted in natural (forest) and semi-natural (peatland) ecosystem types. The published datasets stress the importance of recent advancements in laser spectrometry and help improve our understanding of the temporal variability of surface-atmosphere exchange in different ecosystems, thereby providing validation opportunities for inferential models simulating the exchange of reactive nitrogen.</p>
Data for: Reburning before recovery: Effects of short-interval fire on subalpine forest nitrogen stocks and fluxes
In forests adapted to infrequent (>100-yr) stand-replacing fires, novel short-interval (<30-yr) fires have started to burn young forests before they recover from previous burns. Postfire tree regeneration is reduced, plant communities shift, soils are hotter and drier, but effects on biogeochemical cycling are unresolved. This study focused on how postfire nitrogen (N) stocks, N availability and N fixation varied in lodgepole pine (Pinus contorta var. latifolia) forests burned at long and short intervals in Grand Teton National Park (Wyoming, USA). This data package includes our field data from 2021 and 2022, along with laboratory analyses of foliar and litter chemistry, resin-sorbed N, and field measurements of N fixation. The data included here were also used to compute aboveground N stocks. Our study found that short-interval fires reduced and repartitioned aboveground N stocks, but soil N stocks were unaffected. Results indicate that these shifts in N pools and fluxes suggest reburns can markedly alter N cycling in subalpine forests. The citation for the publication associated with these data is: Turner, M. G., R. E. Heumann, N. G. Kiel, J. A. Warren, and C. C. Cleveland. Reburning before recovery: Effects of short-interval fire on subalpine forest nitrogen stocks and fluxes. Ecosystems (In press)
SBC LTER : Reef: Dissolved nitrogen fluxes from kelp forest sediment
Permeable marine sediments are biogeochemically active and may contribute dissolved nutrients to support primary production in coastal regions. This study examined the potential of permeable marine sediments near giant kelp forests in the Santa Barbara Channel, California to serve as a source of dissolved nutrients to the overlying water column to support the observed growth of kelp during summer months when nitrate availability is low. Over the course of three summers (2017-2019) sediment cores were collected at three nearshore kelp forest sites (ABUR, MICR, GOLB), and flow-through bioreactor incubations were conducted to measure nutrient fluxes. Data are contained in two tables: 1) changes in nutrient concentrations measured over the course of both control (seawater only) and experimental (seawater + sediment) incubations (µM hr-1) and 2) net fluxes of nutrients from sediments (µmol m-2 hr-1). This data package is to support manuscript “Lowman H., Hirsch M., Brezinkski M., and Melack J. Examining the Potential of Sandy Marine Sediments Surrounding Giant Kelp Forests to Provide Recycled Nutrients for Growth. Journal of Coastal Research.”
Fluxes of particulate organic carbon, nitrogen and mass from the Station M abyssal time series in the northeast Pacific, (1989-2022)
<p>Overview:</p> <p>This dataset provides particulate fluxes to Station M in the NE Pacific, from 1989 to 2022. Samples were collected with McLane Parflux sequencing sediment traps deployed on moorings. Data are provided for traps 50 m above bottom and 600 m above bottom, with deployment bottom depths ranging from approximately 3900 m to 4500 m. Gaps reflect lapses in funding, weather disruptions, clogs in sediment traps, or the occasional spilled sample. Where available, GPS coordinates and ship-recorded bottom depth at deployment location are given. Where these are not available, approximate location and depth are given and noted.</p> <p> </p> <p>Methods:</p> <p>This program used McLane Parflux sequencing sediment traps. Attempts to avoid sediment trap clogs, which increasingly became an issue, included replacing manufacture-supplied plastic funnels with Teflon-coated fiberglass funnels (October 2014), doubling the size of sediment trap collection cups (from 250 ML to 500 ML starting in October 2014), and adding a function that periodically agitated material in the funnel constriction (starting in June 2015).</p> <p>Before deployment, sediment trap cups were acid-washed and filled with a preservative (mercuric chloride from 1989 to 2009, 3%–5% buffered formalin from 2009 to 2022). Formalin brine recipe followed that recommended by McLane. Following sample recovery, zooplankton that many have swum into the traps were identified visually and manually removed (KLS). Samples were returned to the lab, freeze-dried, and weighed to calculate mass flux. The freeze-dried sample was analyzed for inorganic carbon content using a coulometer (UIC), and total carbon, hydrogen, and nitrogen using an elemental analyzer (Perkin-Elmer or Exeter Analytical, University of California Santa Barbara Marine Science Institute Analytical Laboratory). Dry mass was corrected for salt content using a AgNO<sub>3</sub> titration (<a href="https://www.sciencedirect.com/science/article/pii/S0967064519302395#bib99">Strickland and Parsons, 1972</a>). Data [mass flux, particulate organic carbon flux, and total nitrogen flux] from the 600 mab trap were used. Gaps in this data set were infilled using the linear relationship between data from the 600 mab and 50 mab traps. Full details of these methods can be found in Baldwin et al. (<a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2022GL101018#grl65243-bib-0002">1998</a>).</p> <p>Data provided have been quality-controlled, and only usable data are included here.</p> <p> </p> <p>References:</p> <p>Baldwin, R. J., Glatts, R. C., & Smith Jr, K. L. (1998). Particulate matter fluxes into the benthic boundary layer at a long time-series station in the abyssal NE Pacific: composition and fluxes. Deep Sea Research Part II: Topical Studies in Oceanography, 45(4-5), 643-665.</p> <p>Strickland, J.D.H., Parsons, T.R. (1972) A Practical Handbook of Seawater Analysis. Fisheries Research Board of Canada, Ottawa </p> <p>Smith, K. L., Huffard, C. L., & Ruhl, H. A. (2020). Thirty-year time series study at a station in the abyssal NE Pacific: An introduction. <em>Deep Sea Research Part II: Topical Studies in Oceanography</em>, <em>173</em>, 104764.</p>
Leaf area, biomass, carbon and nitrogen content by species for harvests taken as part of the ITEX flux survey.
Leaf area, biomass, foliar carbon and nitrogen by species for destructive vegetation harvests. Plots were located in the Toolik Lake LTER fertilization experiment in Alaska; at Imnavait Creek, Alaska; at Paddus, Latnjajaure and the Stepps site near Abisko in northern Sweden; and at various sites in Adventdalen, Svalbard, in Zackenberg valley, Northeast Greenland, and at BEO near Barrow, Alaska. Harvests were taken during the growing seasons 2003 to 2009.
Interactive effects of hemlock mortality and nitrogen availability on nutrient pools and fluxes in the southern Appalachian mountains from 2009 to 2011
The impacts of exotic insects and pathogens on forest ecosystems are increasingly recognized, yet the factors influencing the magnitude of effects remain poorly understood. Eastern hemlock (Tsuga canadensis) exerts strong control on nitrogen (N) dynamics, and its loss due to infestation by the hemlock woolly adelgid (Adelges tsugae) is expected to affect nutrient dynamics in impacted stands. We evaluated the potential for variation in N availability to influence the magnitude of effects of hemlock decline on N and P dynamics in mixed hardwood stands. We measured N and P pools and fluxes at three elevations (low, mid, high) subjected to increasing atmospheric N deposition where hemlock was declining or absent (as reference) in western North Carolina. Specifically, this study was conducted at Coweeta Hydrologic Laboratory, a USDA Forest Service experimental forest in the southern Appalachian mountains of western North Carolina, USA from October 2009 to February 2011.
Sediment oxygen, di-nitrogen (gas), nitrate, nitrite, ammonium, phosphate, and silicate flux from sealed, whole sediment core incubations from a fertilized (Sweeney) and reference (West) creek in the Plum Island Estuary, Massachusetts.
Salt marsh ecosystems serve as critical nutrient filters by removing reactive nitrogen (N) through denitrification. We examined the influence of long-term fertilization on N transformation and removal in a salt marsh tidal creek ecosystem fringing the Plum Island Sound estuary in northern Massachusetts, USA. Sediment oxygen demand was within the range of other marsh systems (1271.9 to 7855.0 µmol m-2 h-1) and was not significantly different between the fertilized and reference creek. Net N2 fluxes ranged from net N fixation of -402.7 µmol N2-N m-2 h-1 in the reference creek to net denitrification of 524.9 µmol N2-N m-2 h-1 in the fertilized creek. Net N2 flux and nitrate uptake were significantly higher in the fertilized creek, and in both creeks, net denitrification appeared to be nitrate limited. We calculated rates of dissimilatory nitrate reduction to ammonium (DNRA) and found it to be significantly higher in the fertilized creek, representing 45 and 11% of the total nitrate uptake in the fertilized and reference creeks, respectively. Additionally, there was a strong relationship between ammonium and nitrite fluxes in both creeks. These results suggest that DNRA may outcompete denitrification at high nitrate concentrations. Increased anthropogenic nutrient loading may therefore have a detrimental effect on the N removal capacity of salt marsh ecosystems. (From: Vieillard and Fulweiler (2012) Marine Ecology Progress Series 147: 11-22. DOI:10.3354/meps10013).
Water column nitrate and ammonium concentrations, sediment oxygen, di-nitrogen (gas), nitrate, nitrite, ammonium, phosphate, and silicate flux from sealed, whole core incubations, Rowley River, Rowley, MA.
Tidal flats are critical components of coastal estuarine ecosystems characterized by high rates of benthic primary productivity and biogeochemical cycling. In order to investigate the impact of anthropogenic nutrient loading on tidal flat biogeochemistry we carried out a two-week fertilization experiment. Throughout the course of the study we conducted two light-dark, whole-core incubations and took measurements of three indicators of microphytobenthos activity in addition to quantifying the resident eastern mud snail (Ilyanassa obsoleta) population.
A Baseline of Terrestrial Freshwater and Nitrogen Fluxes to the Southern California Bight, USA
<p>Terrestrial freshwater discharges into the Southern California Bight (SCB) contains nutrient and carbonate system constituents that make the region susceptible to eutrophication. This respository contains comprehensive time series discharge and constituent data of point and non-point sources, which consist of ocean outfalls, inland wastewater treatment plants, and rivers, to the SCB from the past twenty years and more. Constituents include nitrogen (N), phosphorus (P), carbon (C), iron (Fe), silica (Si) and carbonate system parameters. Many local and state government and non-government organization databases were accessed to construct this data set. In-house data that was previously not publicly available are published here as well. Predictive models and expert analysis addressed unmonitored sources and data gaps. </p> <p>The spreadsheet 'rivers_1997_2017_daily.xlsx' contains the data from 1997 to 2017 for 75 rivers alphabetically. River constituents include discharge volume, ammonium, nitrate, dissolved oxygen, temperature, pH, total N, total P, phosphate, organic P, total organic C, organic N, total Fe, alkalinity, salinity, dissolved Fe, total inorganic C, and silicate.<br> File 'major_potw_1971_2017.xlsx' contains data from 1971 to 2017 for the four large POTWs in the SCB, of which data before 2007 was not publicly available until now. Constituents in this file are discharge volume, ammonium, nitrate, nitrite, dissolved oxygen, temperature, biological oxygen demand, pH, TP, phosphate, OP, TOC, ON, TN, total Fe, silicate, alkalinity, salinity, and dissolved Fe. <br> The 'minor_potw_1997_2017.xlsx' contains data from 1997 to 2017 for the 19 minor POTWs alphabetically. Data from year 2000 was not publicly available until now. Constituents in this file are discharge volume, ammonium, nitrate, nitrite, dissolved oxygen, temperature, biological oxygen demand, pH, TP, phosphate, OP, TOC, ON, TN, total Fe, silicate, alkalinity, salinity, and dissolved Fe. <br> The 'inland_POTW.xlsx' file contains averaged data from the year 2009, unless otherwise noted, for the 18 inland POTWs. The region and city given for each plant. The discharge volume, TN, TP, dissolved inorganic N, and dissolved inorganic P are listed for each plant. <br> The 'natural_rivers.xlsx' file contains summarized annually averaged input of natural riverine sources for each region of the SCB. The approximate watershed area of each region is given and constituents in this file are TN, TP, DIN, and DIP.</p>
Data and code for: Influence of atmospheric nitrogen deposition on soil greenhouse gas fluxes from forests in China and the world
<p><span>Since the industrial revolution, greenhouse gas emissions (particularly CO<sub>2</sub>, CH<sub>4</sub>, and N<sub>2</sub>O) caused by human activities have accelerated global climate change. To avoid catastrophic transitions in the Earth system, many countries including China have set goals to achieve “net zero emission” (or “carbon neutrality”) by mid-21<sup>st</sup> century. Forestland-related practices are among the most preferred “natural climate solutions”. However, high uncertainties remain in the greenhouse gas fluxes from forest soils, because of the limited capability to observe soil dynamics at a large spatial scale. Meanwhile, forest soil greenhouse gas fluxes are influenced by multiple anthropogenic environmental changes including enhanced atmospheric nitrogen deposition, which further complicates the interactions between forest ecosystem and the atmosphere. During the past half century, simulated nitrogen deposition (or “nitrogen addition”) experiments have been conducted in various forest sites worldwide, founding a basis for quantifying the spatially-varying responses of soil greenhouse gas flux to nitrogen deposition. </span></p> <p><span>In this research, we systematically synthesized global nitrogen addition experiment data from published literature and public databases, using which we explored the responses of the three major greenhouse gases to N input. Derived sensitivity of soil N<sub>2</sub>O emission to N deposition allowed for determining the N saturation (or limitation) status of global forests. Using process-augmented data-driven approach and random forest regression models, we estimated soil greenhouse gas budgets on regional and global levels. On the basis, we quantified the varying effects of N deposition on soil greenhouse gas fluxes in N-limited and N-saturated forests across biomes. </span><span> </span></p> <p><span>The produced global map of N-saturated forests in this research could facilitate studies on carbon and nitrogen cycles and improve forest nitrogen management. The revealed response patterns and response factors of soil greenhouse gases to N input could help improve the structure and parameters of ecosystem models. Furthermore, the localized N<sub>2</sub>O emission factors for 145 countries could be used to reduce the uncertainties in their national greenhouse gas inventories. The “process-augmented data-driven” approach could potentially bridge the gap between site-level manipulative experiments and the demand for regional greenhouse gas budgets, allowing manipulative experiments to play a more important role in global change research. </span></p>
Data from: Desiccation and rehydration of mosses greatly increases resource fluxes that alter soil carbon and nitrogen cycling
1. Mosses often have positive effects on soil carbon and nitrogen cycling, but we know little about how environmentally determined cycles of desiccation and rehydration in mosses influence these processes. 2. In this context, we compared carbon and nitrogen in throughfall after precipitation passed through eight moss species that were either hydrated continuously or desiccated and rehydrated. Also, the throughfall of four moss species was added to soil and used to determine the net effect of carbon and nitrogen added in moss throughfall on soil CO2 and N2O efflux. 3. Depending on the species, desiccated-rehydrated (rehydrated) mosses lost 2-31 times more carbon in throughfall than mosses that were continuously hydrated (hydrated). Hydrated mosses lost little to no detectable nitrogen; whereas most rehydrated mosses lost some nitrogen in throughfall. Throughfall from both hydrated and rehydrated mosses generated higher CO2 and N2O efflux than water treated soils, but rehydrated moss throughfall promoted larger N2O efflux than hydrated moss throughfall. Throughfall from hydrated mosses caused net negative changes in soil carbon and had very little effect on soil nitrogen, whereas throughfall from rehydrated mosses generated positive changes in soil carbon and nitrogen. 4. Synthesis. Our results indicate that resources lost from desiccated mosses during rehydration influence soil carbon and nitrogen transformations and may be important drivers of carbon and nitrogen cycling and storage in ecosystems.
Mycorrhizal effects on decomposition and soil CO2 flux depend on changes in nitrogen availability during forest succession
<p>Mycorrhizal fungi play a central role in plant nutrition and nutrient cycling, yet our understanding on their effects on free-living microbes, soil carbon (C) decomposition and soil CO2 fluxes remains limited.</p> <p>Here we used trenches lined with mesh screens of varying sizes to isolate mycorrhizal hyphal effects on soil C dynamics in subtropical successional forests.</p> <p>We found that the presence of mycorrhizal hyphae suppressed soil CO2 fluxes by 17% in early-successional forests, but enhanced CO2 losses by 20% and 32% in mid- and late-successional forests, respectively. The inhibitory effects of mycorrhizal fungi on soil CO2 fluxes in the young stands were associated with changes in soil nitrogen (N) mineralization and microbial activities, suggesting that competition between mycorrhizae and saprotrophs for N likely suppressed soil C decomposition. In the mid- and late-successional stands, mycorrhizal enhancement of CO2 release from soil likely resulted from both hyphal respiration and mycorrhizal-induced acceleration of organic matter decay.</p> <p>Synthesis. Our results highlight the sensitivity of mycorrhizal fungi-saprotroph interactions to shifts in nutrient availability and demand, with important consequences for soil carbon dynamics particularly in ecosystems with low nutrient conditions. Incorporating such interactions into models should improve the simulations of forest biogeochemical cycles under global change.</p>
Enhanced isohydric behavior decoupled the whole-tree sap flux response to leaf transpiration under nitrogen addition in a subtropical forest
<p><span>Anthropogenic nitrogen deposition has the potential to change the leaf water-use strategy in the subtropical region of China. Nevertheless, the whole-tree level response crucial for ecosystem functions has not been well addressed over the past decades. In this study, the stem sap flux density (J<sub>S</sub>) was monitored for the whole-tree water transport capacity in two dominant species (<em>Schima</em> <em>superba</em> and <em>Castanopsis</em> <em>chinensis</em>) in a subtropical forest. To simulate the increased nitrogen deposition, the NH<sub>4</sub>NO<sub>3</sub> solutions were sprayed onto the forest canopy at 25 kg </span><span>ha<sup>-1</sup> year<sup>-1</sup></span><span> (CAN25) and 50 kg ha<sup>-1</sup> year<sup>-1</sup> (CAN50), respectively, since April 2013. The </span><span>J<sub>S</sub></span><span> and microclimate (monitored since January 2014) derived from the whole-tree level </span><span>stomatal conductance </span><span>(G<sub>S</sub>) were used to quantify the stomatal behavior </span><span>(G<sub>S</sub> sensitive to</span><span> vapor pressure deficit</span><span>, G<sub>S-VPD</sub>)</span><span> in response to the added nitrogen. </span><span>The maximum shoot hydraulic conductance (Kshoot-max) was also measured for both species. After one year of monitoring</span><span> in January 2015, the </span><span>mid-day (J<sub>S-mid</sub>) and daily mean (J<sub>S-mean</sub>) sap flux rates did not change under all the nitrogen addition treatments (p > 0.05). A consistent</span><span> decline in the </span><span>G<sub>S-VPD</sub></span><span> indicated an enhanced isohydric behavior for both species. In addition, the G<sub>S-VPD</sub></span><span> in the wet season was much lower than that in the dry season. </span><span><em>S</em>. <em>superba</em> </span><span>had a lower </span><span>G<sub>S-VPD</sub></span><span> and decreased J<sub>S-mid</sub>/J<sub>S-mean</sub>, implying a stronger stomatal control under the fertilization, which might be attributed to the low efficient diffuse-porous conduits and a higher JS. In addition, the G<sub>S</sub> for </span><span><em>S</em>. <em>superba</em></span><span> decreased and the </span><span>G<sub>S-VPD</sub></span><span> increased more under CAN50 than that under CAN25, indicating that the high nitrogen dose restrains the extra nitrogen benefits. Our results indicate</span><span>d</span><span> that the J<sub>S</sub> for both species was decoupled from the leaf transpiration for both species due to an enhanced isohydric behavior, and a xylem anatomy difference and fertilization dose would affect the extent of this decoupling relation.</span></p>
ScienceDex guides
Understand access before you commit
These curated guides explain access requirements, typical timelines, costs, and reuse considerations for widely used research datasets.
Allen Brain Atlas
Allen Brain Atlas is an Allen Institute collection of brain map atlases, datasets, APIs, and analysis tools covering mouse, human, and non-human primate brain resources.
Annotated Behaviour and Observability Dataset (ABODe)
ABODe is a University of Edinburgh DataShare dataset for behavior classification in group-housed mice using home-cage video, identities, bounding boxes, ground-plate positions, and annotator labels.
DANDI Archive for NWB datasets
DANDI is a BRAIN Initiative archive for publishing and sharing neurophysiology data, including electrophysiology, optophysiology, and behavioral data packaged as NWB and related standards.
International Brain Laboratory public data
The International Brain Laboratory public data releases expose standardized mouse decision-making experiments, including Neuropixels recordings, widefield calcium imaging, behavior, and session metadata accessed through the ONE API.
OpenNeuro
OpenNeuro is a free, open platform for sharing neuroimaging datasets, with public search, dataset pages, and download paths for web, S3, DataLad, and the OpenNeuro CLI.