Data file describing the bacterial production and bacterial respiration of water samples collected at various sites near Toolik Lake on the North Slope of Alaska. Sample site descriptors include site, date, time, depth, and category representing severity of thermokarst disturbance. A synthesis of the data presented here is published in Cory et al. 2013, PNAS 110:3429-3434, and in Cory et al. 2014, Science 345:925-928.
Data Set Results
The Anaktuvuk River Fire occurred in 2007 on the North Slope of Alaska. In 2008, three eddy covariance towers were established at sites representing unburned tundra, moderately burned tundra, and severely burned tundra. Eriophorum vaginatum flowers were counted from annual photographs of each site during peak flowering season (6/17-7/20).
The Anaktuvuk River Fire occurred in 2007 on the North Slope of Alaska. In 2008, three eddy covariance towers were established at sites represent ing unburned tundra, moderately burned tundra, and severely burned tundra. During the 2008-2014 growing seasons, canopy vegetation within the footprint of each of these towers was scanned with a handheld spectrophotometer several times throughout the growing season. Average reflectance spectra per site and collection day are presented here.
A rock-scrubbing technique was used to collect bottom samples at several different stations with three replicates at each station in the Kuparuk River. The stations are measured relative to the 1984 phosphorus dripper. Only July sampling dates are included in this file (ACG). The samples were preserved in ethanol then picked, sorted, counted, and measured in Duluth using a NIKON MICRO-PLAN II digitizing pad.
A Surber sampler (25 X 25 cm frame fitted with a 243 um mesh net) was used to sample invertebrates at several different stations. Two replicates were taken from each station. The same sampling procedure was used for all dates. The stations were measured relative to the site of the dripper ("-" = upstream of the dripper). Samples were preserved in 4% formaldehyde and transported to Orono, Maine, where invertebrates were removed by hand under 15X magnification and then identified and counted. All values are converted to individuals per square meter.
A Surber sampler (25 X 25 cm frame fitted with a 243 um mesh net) was used to sample invertebrates on a single date at each site. Five replicates were taken from at least two riffles at each site. Samples were preserved in 4% formaldehyde and transported to Orono, Maine, where invertebrates were removed by hand under 15X magnification and then identified and counted. All values are the mean of five replicates and have been converted to individuals per square meter.
Data on the effects of shading tundra vegetation from the sun when it is low in on the horizon in the north. If light quality was altered through shading, phenology might be affected. Senescence (color change) was measured for the common tundra species.
Data on Eriophorum vaginatum leaf length collected from common gardens established at Toolik Lake, Coldfoot, and Sagwon in 2014 with tussocks from Coldfoot, Toolik Lake, and Sagwon. Data collected during the growing seasons of 2015, 2016, and 2017
This was an experimental burn conducted in the summer of 2015 to provide sites for an experiment to see 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 have been collected on the plots.
We use a simple model of coupled carbon and nitrogen cycles in terrestrial ecosystems to examine how explicitly representing grazers versus having grazer effects implicitly aggregated in with other biogeochemical processes in the model alters predicted responses to elevated carbon dioxide and warming. The aggregated approach can affect model predictions because grazer-mediated processes can respond differently to changes in climate from the processes with which they are typically aggregated.
Surber sampler (25 X 25 cm frame fitted with a 243 um mesh net) was used to sample invertebrates at on the Kuparuk River in Reference (2001-2012) and Fertilized Reach (2002-2016) reach.
We used a fully factorial experiment to test effects of food availability and temperature (7.6, 12.7 and 17.4 degrees C; 50 days) on growth, consumption, respiration, and excretion of slimy sculpin (Cottus cognatus).
We use a simple model of coupled carbon and nitrogen cycles in terrestrial ecosystems to examine how explicitly representing grazers versus having grazer effects implicitly aggregated in with other biogeochemical processes in the model alters predicted responses to elevated carbon dioxide and warming. The aggregated approach can affect model predictions because grazer-mediated processes can respond differently to changes in climate from the processes with which they are typically aggregated.
This dataset consists of tussock density, mortality rates and causes, and an assesment of rodent-herbivore activity levels in previously burned (2007 Anaktuvuk River fire) and unburned tussock tundra. Eriophourm vaginatum tussocks were counted every meter within a 1 square meter quadrat along three transects. Cause of tussock mortality, as well as level of rodent herbivory was assessed for each tussock, and rodent herbivore activity was assessed for each quadrat.