Nitrogen mineralization was determined on LTER and Sag River tussock tundra using the buried bag method. Yearly bags have been deployed every August since 1990.
Data Set Results
Displaying 151 - 200 of 215
A spectrophotometer was used to scan the canopy vegetation of ITEX flux plots. The resulting reflectance spectra were used to calculate several vegetation indices of interest (NDVI, EVI, EVI2, PRI, WBI, Chlorophyll Index). Average values of these vegetation indices for each ITEX flux plot are presented here.
Above ground plant biomass was measured in a tussock tundra experimental site. The plots were set up in 1981 and have been harvested in previous years (See Shaver and Chapin Ecological Monographs, 61(1), 1991 pp.1-31.) This file is the July 26-27, 1984 harvest of the controls and nitrogen + phosphorus treatments.
Output data sets of the MBL-GEM III model for a typical tussock-tundra hill slope. The model is described in two papers:
Le Dizès, S., Kwiatkowski B.L., Rastetter E.B., Hope A., Hobbie J.E., Stow D., Daeschner S., 2003 Modelling biogeochemical responses of tundra ecosystems to temporal and spatial variations in climate in the Kuparuk River Basin (Alaska), Journal of Geophysical Research Vol. 108 No. D2 10.1029/2001JD000960.
Output data set of the MBL-GEM III model run for tussock tundra in the Kuparuk River Basin, Alaska, described in detail in Le Dizès, S., B. L. Kwiatkowski, E. B. Rastetter, A. Hope, J. E. Hobbie, D. Stow, and S. Daeschner, Modeling biogeochemical responses of tundra ecosystems to temporal and spatial variations in climate in the Kuparuk River Basin (Alaska), J. Geophys. Res., 108(D2), 8165, doi:10.1029/2001JD000960, 2003.
Since 1983, the Streams Project at the Toolik Field Station has monitored physical, chemical, and biological parameters in a 5-km, fourth-order reach of the Kuparuk River near its intersection with the Dalton Highway and the Trans-Alaska Pipeline. In 1989, similar studies were begun on a 3.5-km, third-order reach of a second stream, Oksrukuyik Creek.
Water chemistry (NO3, NH4, TDN, DON, DOC) from Imnavait watershed along hillslope. Sample waters were either collected by lysimeters, needle with syringe, or extracting soil with water or 1N KCl.
Concentrations of NO3 and NH4 and d15N of NO3 and NH4 collected on resin bags from 15N addition plots along hillslope in Imnavait watershed.
Percent carbon and percent nitrogen were measured from above ground plant and belowground stem biomass samples from experimental plots in moist acidic and moist non-acidic tundra. Biomass data are in 2001lgshttbm.dat.
Aboveground plant and belowground stem biomass were measured in moist acidic and moist non-acidic tussock tundra experimental plots. Treatments at the acidic site include control and nitrogen (N) plus phosphorus (P) amendments; treatments at the non-acidic site include N, P, N+P, greenhouse warming, and greenhouse+N+P.
Note: Version 8 corrected an error where Carex vaginata was listed twice under treatment of "Nitrogen Phosphorus". The tissues with 8 quadrats were "Greenhouse" treatment.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Yearly file containing information on bacterial productivity. Samples were collected at various sites near Toolik Research Station (68 38'N, 149 36'W). Sample site descriptors include an assigned number (sortchem), site, date, time and depth.
Decadal file describing the water chemistry in various lakes near Toolik Research Station (68 38'N, 149 36'W) during summers from 1990 to 1999. Chemical analyses were conducted on samples from various depths in the sample lakes either once, or multiple times during the spring, summer and fall months (May to September).
Decadal file describing the water chemistry in various lakes near Toolik Research Station (68 38'N, 149 36'W) during summers from 2000 to 2009. Chemical analyses were conducted on samples from various depths in the sample lakes either once, or multiple times during the spring, summer and fall months (May to September).
Note: Corrections were made to Particulate phosphorus values. See version 5 notes.
Decadal file describing the water chemistry in various lakes near Toolik Research Station (68 38'N, 149 36'W) during summers from 1983 to 1989. Chemical analyses were conducted on samples from various depths in the sample lakes either once, or multiple times during the spring, summer and fall months (May to September).
The Kuparuk River has been the central research location on the impact of added phosphorus to arctic streams. Additions of phosphorus occred since 1983. Today, 4 specific reaches show certain characteristics based on the years that they recieved fertilization. Whole Stream Metabolism is a way to quantify primary production of this stream system. Calculations were done using dissolved oxygen, discharge, stage, light and temperature measured by sondes and other equipment strategically deployed in the field at locations to quantify each of the unique stream reaches.
A study investigating the mechanisms that control long-term response of tussock tundra to fire and to increases in air temperature, CO2, nitrogen deposition and phosphorus weathering. The MBL MEL was used to simulate the recovery of three types of tussock tundra, unburned, moderately burned, and severely burned in response to changes in climate and nutrient additions. The simulations indicate that the recovery of nutrients lost during wildfire is difficult under a warming climate because warming increases nutrient cycles and subsequently leaching within the ecosystem.
The data set describes stable carbon and nitrogen isotopes and carbon and nitrogen concentrations from an August 2012 pluck of a fertilization experiment begun in 2006. Fertilization was with nitrogen (N) and phosphorus (P). Fertilization levels included control, F2, F5, and F10, with F2 corresponding to yearly additions of 2 g/m2 N and 1 g/m2 P, F5 corresponding to yearly additions of 5 g/m2 N and 2.5 g/m2 P, and F10 corresponding to yearly additions of 10 g/m2 N and 5 g/m2 P. After harvest, plants were separated by species and then by tissue.
Decadal file describing the chlorophyll a and primary production in various lakes near Toolik Research Station (68 38'N, 149 36'W) during summers from 2000 to 2009. Sample site descriptors include an assigned number (sortchem), site, date of analysis (incubation), time, depth and rates of primary production. The amount of chlorophyll a and pheophytin were also measured.
Relative percent cover was measured for plant species on Arctic LTER experimental plots at Toolik field station in moist acidic and non-acidic tundra.
Measures of soil nutrient content (available N and P, Extractable N and P, Total C, N and P), and microbial biomass and activity (exoenzyme activity) were measured for organic and mineral soils on Arctic LTER experimental plots at Toolik field station in moist acidic and non-acidic tundra (organic soils only).
An experimental burn conducted in the summer of 2015 to provide sites for an experiment whether seeds of Eriophorum vaginatum from different ecotypes could establish in recently burned areas. It consisted of ten 2 meter X 2 meter plots along with a similar number of control plots. There was little seedling establishment but other data were collected on the plots. Ion exchange membranes were used to measure nutrient availability over two time periods: Early season (June) and mid season (July).
Quantum yield of Photosystem II estimated from chlorophyll fluorescence of Eriophorum vaginatum leaves from tussocks in the reciprocal transplant gardons at Toolik Lake, Coldfoot, and Sagwon in 2016. A single transplant tussock per plot was repeatedly measured through the season.
Transplant gardens at Toolik Lake and Sagwon were established in 2014. At each location, 60 tussocks each from ecotypes of Eriophorum vaginatum from Coldfoot (CF, 67°15′32″N, 150°10′12″W), Toolik Lake (TL, 68°37′44″N, 149°35′0″W), and Sagwon (SG, 69°25′26″N, 148°42′49″W) were transplanted. At the reciprocal transplant gardens, ion exchange membranes were used to measure nutrient availability over two time periods: Early season (June) and mid season (July). Membranes were deployed in the field for either 20 or 21 days, depending on travel constraints.
Data file of the biogeochemistry of samples collected at various sites near Toolik Lake, North Slope of Alaska. Sample site descriptors include a unique assigned number (sortchem), site, date, time, depth, distance (downstream from a reference location), elevation, treatment, date-time, category, and water type (lake, surface, soil). Physical measures collected in the field include temperature (water, soil, well water), conductivity, pH, and average thaw depth in soil. Chemical analyses for the sample include alkalinity; dissolved inorganic and organic carbon (DIC and DOC); dissolved gas
Two Figaro TGS 2600 sensors were installed at the Toolik Wet Sedge site in late June 2012 to 2018.
Soil stratification was determined by measuring the vertical thickness of three main strata (surface acrotelm, mid-depth catotelm, and bottom mineral soil) found in organic-rich or peat soils in the Toolik Lake region, North Slope of Alaska. Additional data for each site include dominant vegetation, landscape position, glacial surface, and microtopography.
Soil cores of 5 cm diameter down to frozen
Dissolved organic carbon (DOC) was leached from permafrost soils near the Toolik Field Station in the Alaskan Arctic and then characterized for its photochemical properties. Oxygen (O2) consumed from photo-oxidation of permafrost DOC was measured as a function of sunlight wavelength, defined as the apparent quantum yield spectrum of photo-oxidation (O2 consumed per mol photon absorbed by DOC). Carbon dioxide (CO2) produced from photomineralization of permafrost DOC was measured as a function of sunlight wavelength, defined as the apparent quantum yield spectrum of photomineralization (CO2
Dissolved organic carbon (DOC) was leached from p
Dissolved organic carbon (DOC) was leached from permafrost soils near the Toolik Field Station in the Alaskan Arctic and then characterized for its photochemical properties. The photodegradation of carboxyl carbon (C) within permafrost DOC was quantified by 13C nuclear magnetic resonance (NMR).
Soils were collected from the frozen permafrost layer (greater than 60 cm below the surface) at six sites underlying tussock or wet sedge vegetation, and on three glacial surfaces on the North Slope of Alaska during the summers of 2015 and 2018. Dissolved organic carbon (DOC) was leached from each permafrost soil and the water chemistry was analyzed.
Dissolved organic carbon (DOC) was leached from permafrost soils near the Toolik Field Station in the Alaskan Arctic and then characterized for its photochemical properties. The radiocarbon (14C) and stable carbon (13C) isotopic compositions of carbon dioxide (CO2) photochemically produced from permafrost DOC were quantified.
Dissolved organic carbon (DOC) was leached from permafrost soils collected from the frozen permafrost layer at five sites underlying moist acidic tussock or wet sedge vegetation, and on three glacial surfaces on the North Slope of Alaska during summer 2018.
Dissolved organic carbon (DOC) was leached from permafrost soils near the Toolik Field Station in the Alaskan Arctic and then characterized for its photochemical properties. The apparent quantum yield of photomineralization (photochemical carbon dioxide, CO2, production) of permafrost DOC was quantified at 309 nm.