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43,008 results for “n”
Extracellular enzyme activities in plots dominated by trees that associate with arbuscular mycorrhizal or ectomycorrhizal fungi in the nitrogen fertilized and reference watershed at the Bear Brook Watershed in Maine, USA during the final year of N fertilization (2016) and during the year after N fertilization ceased (2017).
Our objective was to detect possible differences in N fertilization responses of extracellular enzymes in plots dominated by trees that associate with arbuscular mycorrhizal fungi (AM) or ectomycorrhizal fungi (ECM). To do this, we established a plot network of 6 AM and 6 ECM dominated (>65% diameter at breast height) 10 x 10 m plots in the lower elevation hardwood zone of both the reference and N fertilized watersheds (N=24 plots) at Bear Brook Watershed, in Maine USA. We assayed the potential activity of hydrolytic enzymes that release N (N-acetylglucosaminidase; NAG), phosphorus (acid phosphatase; AP), and simple carbon (ß-glucosidase; BG). The activities of these enzymes were measured separately in bulk mineral, rhizosphere, and organic horizon soils in the final year of N fertilization at Bear Brook in 2016 and during the year after N fertilization ceased in 2017.
Characterization of burned and unburned moist acidic tundra sites for estimating C and N loss from the 2007 Anaktuvuk River Fire, sampled in 2008.
Burned and unburned moist acidic tundra sites used to estimate C and N loss from the Anaktuvuk River Fire (2007). These sites were sampled in summer of 2008. Unburned sites were used to develop a method for estimating soil organic layer depth and plant biomass, and for determining the characteristics of unburned soil organic layers. In burned sites, we characterized residual organic soils and used biometric measurements of tussocks to reconstruct pre-fire soil organic layer depth. Together, these measurements were used to reconstruct pre-fire soil and plant carbon and nitrogen pools and estimate ecosystem losses of these elements during the fire.
Precipitation cations and anions for June, July and August from a wet/dry precipitation, University of Alaska Fairbanks Toolik Field Station, North Slope of Alaska (68 degrees 37' 42"N, 149 degrees 35' 46"W), Arctic LTER 1989 to 2003
Precipitation, collected from a wet/dry precipitation collector located near University of Alaska Fairbanks Toolik Field Station, North Slope of Alaska (68 degrees 37' 42"N, 149 degrees 35' 46"W) was sent out for standardized EPA rain water analysis. Nutrient chemistry was also run on a sub sample at the field station.
Effects of experimentally altered wolf spider densities and warming on soil microarthropods, litter decomposition, litter N, and soil nutrients near Toolik Field Station, AK in summer 2012
Predators can disproportionately impact the structure and function of ecosystems relative to their biomass. These effects may be exacerbated under warming in ecosystems like the Arctic, where the number and diversity of predators are low and small shifts in community interactions can alter carbon cycle feedbacks. Here we show that warming alters the effects of wolf spiders, a dominant tundra predator, on belowground litter decomposition and nutrient dynamics. Specifically, while high densities of wolf spiders result in faster litter decomposition under ambient temperatures, they result instead in slower decomposition under warming. Higher spider densities are also associated with elevated levels of available soil nitrogen, potentially benefitting plant production. Changes in decomposition rates under increased wolf spider densities are accompanied by trends toward fewer fungivorous Collembola under ambient temperatures and more Collembola under warming, suggesting that Collembola mediate the indirect effects of wolf spiders on decomposition. The unexpected reversal of wolf spider effects on Collembola and decomposition suggests that in some cases, warming does not simply alter the strength of top-down effects but instead induces a different trophic cascade altogether. Our results indicate that climate change-induced effects on predators can cascade through other trophic levels, alter critical ecosystem functions, and potentially lead to climate feedbacks with important global implications. Moreover, given the expected increase in wolf spider densities with climate change, our findings suggest that the observed cascading effects of this common predator on detrital processes could potentially buffer concurrent changes in decomposition rates.
Model output, drivers and parameters for Ecosystem Recovery from Disturbance is Constrained by N Cycle Openness, Vegetation-Soil N Distribution, Form of N Losses, and the Balance Between Vegetation and Soil-Microbial Processes
Files used to generate the data for figures in: Rastetter, EB, Kling, GW, Shaver, GR, Crump, BC, Gough, L. Ecosystem Recovery from Disturbance Is Constrained by N Cycle Openness, Vegetation-Soil N Distribution, Form of N Losses, and the Balance between Vegetation and Soil-Microbial Processes. Ecosystems (2020). https://doi.org/10.1007/s10021-020-00542-3. This paper present a framework for assessing biogeochemical recovery of terrestrial ecosystems from disturbance. We identify three recovery phases. In Phase 1, nitrogen is redistributed from soil organic matter to vegetation, but the ecosystem continues to lose nitrogen because the recovering vegetation cannot take up nitrogen as fast as it is released from soil. In Phase 2, the ecosystem begins re-accumulating nitrogen and converges on a quasi-steady state in which vegetation and soil-microbial processes are in balance. In Phase 3, vegetation and soil-microbial processes remain in balance and the ecosystem slowly re-accumulates the remaining nitrogen.
Biomass, %N, and %C data for the BBC collapse scar for 2003 and 2004
This data set contains biomass measurements for a destructively harvested transect 30 m to the east of the permanent transect from the center of the BBC collapse scar (0m) into the surrounding fire scar (30m) of the Survey Line Fire (burned in June-July 2001). Biomass samples were collected on DOY 231 2004. Two 61 cm x 61 cm plots were harvested on the east and west side of every point along the transect (0, 6, 12, 18, 24, and 30 m). We sorted these above-ground biomass samples into plant type (Sphagnum spp., other mosses, Marchantia spp., Eriophorum vaginatum, Carex spp., Grasses, Betula spp., Salix spp., Potentilla palustris, Ledum groenlandicum, Vaccinium uliginosum, Vaccinium vitis-idaea, Chamaedaphne calyculata, other vascular plants, dead mosses, dead Carex spp., dead Graminoid, dead Potentilla palustris, dead Salix spp., and other litter). Photosynthetic green tissues were separated from the above-ground biomass samples. Samples were dried at 60degC to measure the dry mass. Samples were also analyzed for %C and %N. We oven-dried at 50 - 65degC and ground all samples before analysis. We analyzed samples for %C and %N using a Carlo Erba EA1108 CHNS analyzer (CE Instruments, Milan, Italy) and a COSTECH ECS 4010 CHNS-O analyzer (Costech Analytical Technologies Inc., Valencia, CA, USA). Sample standard errors were +/- 0.01% for nitrogen, +/- 0.45% for carbon. For the biomass transect samples, we analyzed for %C and %N when the samples were more than 10% of the plot biomass allowing for representative sampling of carbon and nitrogen from the dominant plant types. This data set was collected to monitor the change in biomass across the transect to relate this to disturbance, topography, soils, soil moisture and measured fluxes of CO2 and CH4 emissions.
Biomass %N, %C, natural abundance 15N and 13C isotopic signatures for common and rare under- and overstory plants in long unburned and burned (1999) boreal forest stands, Caribou-Poker Creek and Delta Junction
This dataset contains leaf, aboveground stem, and fruit carbon and N concentration and natural abundance isotope data for new and old tissue fractions of common and rare plant species in burned and unburned black spruce forest stands. Stands were located in either Caribou-Poker Creek or Delta Junction, in either unburned areas, or in areas burned in 1999 fires. Biomass was collected between 2000 and 2001 in mid-July at peak biomass.
Soil C, N, P, and Frankia nifD-K RFLP genotypes distribution from Alnus tenuifolia nodules in early and late succession 2005
This dataset contains genetic characterizations of Frankia inhabiting Alnus tenuifolia nodules in early and late succession sites in the Bonanza Creek Experimental Forest (BCEF). Characterizations were done using PCR-RFLP on the nifD-K spacer region of the Frankia genome. The position of each plant and each nodule were mapped in order to examine spatial patterns in Frankia distribution within sites. Soil chemistry data, including C, N, P, and pH, were also collected from mineral and organic layers.
Post-fire succession in 1994 Hajdukovich Creek Burn: measurements of root biomass, shoot biomass, total plant C content, total plant N content for aspen and spruce
This dataset contains measurements of root biomass, shoot biomass, total plant C, and total plant N of 10 aspen and 10 spruce saplings harvested in one severely burned and one lightly burned site in the 1994 Hajdukovich Creek burn.
N-fixation rate and leaf N content in two species of Alnus and their relationship to diversity of symbiotic Frankia
This study investigated patterns of nitrogen (N) fixation rates, leaf N content, and geographic diversity in the N-fixing bacterium Frankia occurring in symbiosis with Alnus incana ssp. tenuifolia and A. viridis ssp. fruticosa in early and late successional habitats on the Tanana river floodplain and surrounding uplands in the Bonanza Creek Experimental Forest. Frankia diversity was estimated via polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the nifD-K spacer region, a non-coding region in the nitrogenase-encoding operon. Specific N-fixation rate was measured with a 15N2 uptake assay and leaf N content via mass spectrometry. Additional parameters measured were soil temperature and moisture, leaf del 15N, and specific leaf area.
Plant aboveground biomass data: BioCON : Biodiversity, Elevated CO2, and N Enrichment
BioCON (Biodiversity, CO2, and Nitrogen) is an ecological experiment started in 1997 at the University of Minnesota's Cedar Creek Ecosystem Science Reserve. BioCON's goal is to explore the ways in which plant communities will respond to three environmental changes that are known to be occurring on a global scale: increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity. Why Biodiversity, CO2, and Nitrogen? While there are many uncertainties in global change biology, there are also some well documented facts. Some of these are: 1. The amount of carbon dioxide (CO2) in the atmosphere is rising. Since the industrial revolution, the CO2 concentration in the atmosphere has increased from approximately 275 parts per million (ppm) to about 378 ppm today. This has been largely the result of fossil fuel burning. It is expected that CO2 levels will continue to rise, and that by the year 2050 these levels will be approximately 550 ppm. CO2 is the raw material for photosynthesis and is known to affect plant growth and development. 2. The amount of nitrogen moving through terrestrial ecosystems has increased in the recent past. While natural "background" levels of nitrogen fixation have remained constant, human additions to the system through fertilizer production and fossil fuel use have increased dramatically. Nitrogen is a key nutrient for plant growth and plays a critical role in plant community structure and composition in many environments. 3. Biodiversity levels are falling. While the research and data are not as complete as they are for CO2 and nitrogen, data indicate that the number of species globally, is being reduced. Perhaps more important for ecosystem function, diversity levels on local to regional scales have fallen due to land use change, biotic invasion and many other drivers. While much is known about how each of these factors affects ecosystem functioning, many questions remain. There is also little data on how these issues affe
Nitrogen mineralization rate: BioCON : Biodiversity, Elevated CO2, and N Enrichment
BioCON (Biodiversity, CO2, and Nitrogen) is an ecological experiment started in 1997 at the University of Minnesota's Cedar Creek Ecosystem Science Reserve. BioCON's goal is to explore the ways in which plant communities will respond to three environmental changes that are known to be occurring on a global scale: increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity. Why Biodiversity, CO2, and Nitrogen? While there are many uncertainties in global change biology, there are also some well documented facts. Some of these are: 1. The amount of carbon dioxide (CO2) in the atmosphere is rising. Since the industrial revolution, the CO2 concentration in the atmosphere has increased from approximately 275 parts per million (ppm) to about 378 ppm today. This has been largely the result of fossil fuel burning. It is expected that CO2 levels will continue to rise, and that by the year 2050 these levels will be approximately 550 ppm. CO2 is the raw material for photosynthesis and is known to affect plant growth and development. 2. The amount of nitrogen moving through terrestrial ecosystems has increased in the recent past. While natural "background" levels of nitrogen fixation have remained constant, human additions to the system through fertilizer production and fossil fuel use have increased dramatically. Nitrogen is a key nutrient for plant growth and plays a critical role in plant community structure and composition in many environments. 3. Biodiversity levels are falling. While the research and data are not as complete as they are for CO2 and nitrogen, data indicate that the number of species globally, is being reduced. Perhaps more important for ecosystem function, diversity levels on local to regional scales have fallen due to land use change, biotic invasion and many other drivers. While much is known about how each of these factors affects ecosystem functioning, many questions remain. There is also little data on how these issues affe
Soil moisture: BioCON : Biodiversity, Elevated CO2, and N Enrichment
BioCON (Biodiversity, CO2, and Nitrogen) is an ecological experiment started in 1997 at the University of Minnesota's Cedar Creek Ecosystem Science Reserve. BioCON's goal is to explore the ways in which plant communities will respond to three environmental changes that are known to be occurring on a global scale: increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity. Why Biodiversity, CO2, and Nitrogen? While there are many uncertainties in global change biology, there are also some well documented facts. Some of these are: 1. The amount of carbon dioxide (CO2) in the atmosphere is rising. Since the industrial revolution, the CO2 concentration in the atmosphere has increased from approximately 275 parts per million (ppm) to about 378 ppm today. This has been largely the result of fossil fuel burning. It is expected that CO2 levels will continue to rise, and that by the year 2050 these levels will be approximately 550 ppm. CO2 is the raw material for photosynthesis and is known to affect plant growth and development. 2. The amount of nitrogen moving through terrestrial ecosystems has increased in the recent past. While natural "background" levels of nitrogen fixation have remained constant, human additions to the system through fertilizer production and fossil fuel use have increased dramatically. Nitrogen is a key nutrient for plant growth and plays a critical role in plant community structure and composition in many environments. 3. Biodiversity levels are falling. While the research and data are not as complete as they are for CO2 and nitrogen, data indicate that the number of species globally, is being reduced. Perhaps more important for ecosystem function, diversity levels on local to regional scales have fallen due to land use change, biotic invasion and many other drivers. While much is known about how each of these factors affects ecosystem functioning, many questions remain. There is also little data on how these issues affe
Percent light penetration: BioCON : Biodiversity, Elevated CO2, and N Enrichment
BioCON (Biodiversity, CO2, and Nitrogen) is an ecological experiment started in 1997 at the University of Minnesota's Cedar Creek Ecosystem Science Reserve. BioCON's goal is to explore the ways in which plant communities will respond to three environmental changes that are known to be occurring on a global scale: increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity. Why Biodiversity, CO2, and Nitrogen? While there are many uncertainties in global change biology, there are also some well documented facts. Some of these are: 1. The amount of carbon dioxide (CO2) in the atmosphere is rising. Since the industrial revolution, the CO2 concentration in the atmosphere has increased from approximately 275 parts per million (ppm) to about 378 ppm today. This has been largely the result of fossil fuel burning. It is expected that CO2 levels will continue to rise, and that by the year 2050 these levels will be approximately 550 ppm. CO2 is the raw material for photosynthesis and is known to affect plant growth and development. 2. The amount of nitrogen moving through terrestrial ecosystems has increased in the recent past. While natural "background" levels of nitrogen fixation have remained constant, human additions to the system through fertilizer production and fossil fuel use have increased dramatically. Nitrogen is a key nutrient for plant growth and plays a critical role in plant community structure and composition in many environments. 3. Biodiversity levels are falling. While the research and data are not as complete as they are for CO2 and nitrogen, data indicate that the number of species globally, is being reduced. Perhaps more important for ecosystem function, diversity levels on local to regional scales have fallen due to land use change, biotic invasion and many other drivers. While much is known about how each of these factors affects ecosystem functioning, many questions remain. There is also little data on how these issues affe
Photosynthesis (A max, etc.): BioCON : Biodiversity, Elevated CO2, and N Enrichment
BioCON (Biodiversity, CO2, and Nitrogen) is an ecological experiment started in 1997 at the University of Minnesota's Cedar Creek Ecosystem Science Reserve. BioCON's goal is to explore the ways in which plant communities will respond to three environmental changes that are known to be occurring on a global scale: increasing nitrogen deposition, increasing atmospheric CO2, and decreasing biodiversity. Why Biodiversity, CO2, and Nitrogen? While there are many uncertainties in global change biology, there are also some well documented facts. Some of these are: 1. The amount of carbon dioxide (CO2) in the atmosphere is rising. Since the industrial revolution, the CO2 concentration in the atmosphere has increased from approximately 275 parts per million (ppm) to about 378 ppm today. This has been largely the result of fossil fuel burning. It is expected that CO2 levels will continue to rise, and that by the year 2050 these levels will be approximately 550 ppm. CO2 is the raw material for photosynthesis and is known to affect plant growth and development. 2. The amount of nitrogen moving through terrestrial ecosystems has increased in the recent past. While natural "background" levels of nitrogen fixation have remained constant, human additions to the system through fertilizer production and fossil fuel use have increased dramatically. Nitrogen is a key nutrient for plant growth and plays a critical role in plant community structure and composition in many environments. 3. Biodiversity levels are falling. While the research and data are not as complete as they are for CO2 and nitrogen, data indicate that the number of species globally, is being reduced. Perhaps more important for ecosystem function, diversity levels on local to regional scales have fallen due to land use change, biotic invasion and many other drivers. While much is known about how each of these factors affects ecosystem functioning, many questions remain. There is also little data on how these issues affe
Measurements of Soil %C and %N at the Coweeta LTER Terrestrial Gradient Sites, Coweeta Hydrological Laboratory, Otto, NC.
This project is part of a larger examination of site productivity along an elevational gradient. Soil %C and %N were measured at each of the five terrestrial gradient plots located along an elevational gradient at Coweeta Hydrologic Lab, Otto, NC.
Hubbard Brook Experimental Forest: Hyperspectral Foliar N map and associated field data, 2012
A canopy nitrogen map was created for the Hubbard Brook Experimental Forest and watersheds using airborne imaging spectrometer data collected by SpecTIR LLC (Reno, NV) on August 7, 2012, and associated field data. Leaf samples collected in the field were analyzed for nitrogen concentration, scaled to plot (whole canopy) level, and related to airborne imaging spectrometer reflectance data using partial least squares regression modeling to derive spatially explicit estimates of canopy nitrogen concentration (mass-based) for the spatial extent of the airborne imagery.
Krummholz island soil C and N data for East of Tvan, 1994.
Previous work has shown that passage of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) tree islands across tundra lowers the soil carbon and nitrogen storage capacity of the top 15cm of soil (A horizon) (Pauker and Seastedt 1996). This data forms part of a study which seeks to further examine how changes in carbon storage capacity are associated with changes in soil physical properties. Soils were collected in 1994. We sought to determine whether there were changes in natural abundance of C and N isotopes associated with previously reported changes in C and N content. Any such changes in natural abundance of C and N isotopes may indicate differences in inputs to the ecosystem or differences in ecosystem processes that may account for the differences in N and C content that have been observed. In addition to measuring ratios of natural isotopes of C and N, we also measured C and N contents to provide a comparison with previous studies. To convert % N and C values to kgs of N and C per m2, we used bulk density values, averaged across sampling dates that had been previously measured for these sites. Metadata for these data are available at: https://portal.lternet.edu/nis/mapbrowse?scope=knb-lter-nwt&identifier=131 When N and C soil contents were considered on a percentage basis, levels at windward sites were significantly lower than those of undisturbed tundra, but levels directly beneath krummholz were not significantly different from tundra soils. Bulk density was significantly lower under krummholz than other sites. Thus when N and C amounts were expressed on a volume (Kg/m2, to a depth of 15cm), they were significantly lower in both krummholz and windward sites than in undisturbed tundra. D13C values of soils under krummholz were significantly less negative under krummholz than from windward or undisturbed tundra sites. A less negative d13C value is indicative of less discrimination and may be attributable to either vegetation differences
Krummholz island soil N and root ingrowth data for East of Tvan, 1996 - 1997.
Previous work has shown that passage of Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) tree islands across tundra lowers the soil carbon and nitrogen storage capacity of the top 15cm of soil (A horizon) (Pauker and Seastedt 1996). The presence of tree islands (krummholz) on the tundra acts as a 'snowfence' causing snow to drift within the krummholz and in a semi-circular area leeward of the krummholz. This drifting causes soil within and leeward of the krummholz to have a much deeper, more consistent and longer lasting snow-cover than the adjacent tundra soils. The snowdrifts form a permanent cover over the leeward and krummholz sites from November through June, helping to insulate the soils beneath from the extreme low temperatures and supplying significantly more meltwater in the spring. In contrast, high winds cause the adjacent tundra to be free from snow and exposed to extremely cold temperatures for much of the winter. Studies have shown that atmospheric nitrogen deposition accumulates on snowpacks throughout the winter months and that this is released as a 'pulse' of nitrogen ions at snowmelt (Williams et al. 1996). We hypothesized that accumulation of snowpacks in krummholz and leeward sites may alter nitrogen dynamics in these areas relative to tundra, by either (a) affecting microbial activity via its insulating effect or (b) accumulating large amounts of atmospherically deposited N and releasing it as a pulse at snowmelt. This study sought to examine the nitrogen inputs into tundra, krummholz, and leeward soils over an entire winter season (using buried ion exchange resin bags which collect ions percolating down at snowmelt and early spring rains) and over a short period in spring, immediately following snowmelt (using microlysimeters to collect soil water over a 24 hour period). Belowground NPP (determined from root ingrowth cores) and d13C values of tundra and krummholz vegetation are also presented in this file. NH4+ and NO3-
N and P fertilization experiment net primary productivity data for South of saddle, 1991 - 1997.
A nutrient amendment experiment was initiated in 1990 in 2 alpine plant communities, dry and wet meadow, to determine whether N and/or P limit primary production of these communities, the plants' functional response to increased nutrients, and the community structure and composition responses to changes in nutrient availability.
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Allen Brain Atlas
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DANDI Archive for NWB datasets
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OpenNeuro
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