Vegetation indices calculated from reflectance spectra collected at Arctic LTER plots at Toolik Lake, Alaska during the 2007-2016 growing seasons. Canopy reflectance was measured using a dual channel spectrophotometer (Unispec DC, PP Systems, Amesbury, Massachusetts, USA). Spectral indices were calculated for NDVI (MODIS, EVI (MODIS), EVI2 (MODIS), PRI (550 Reference), PRI (570 Ref), WBI and Chl Index
This dataset includes every pin-hit recorded from 19 1m x 1m point frame plots of tall Betula nana and Salix pulchra canopies sampled at the Toolik Field Station, AK the summer of 2012. Twenty-five evenly spaced holes within the plot were sampled for each point frame for which the height and species was recorded for each leaf, stem, or plant that intersected the pin when lowered perpendicular to the ground. Non-woody species were grouped into functional groups (e.g. forb, graminoid, moss) and not identified to species.
Maximum canopy height measurements for deciduous shrub canopies sampled for both 1m x 1mc hamber flux polots (n=14) and point frame plots (n=19) in the summer of 2012 near LTER shrub plots at Toolik Lake, AK. The canopies were dominated either by Salix pulchra or Betula nana species, and plot locations were preferentially selected for tall canopies (height > 75 cm). The methods for the chamber flux and point frames are outlined here briefly, though the data from these measurements are contained in separate files.
“Flux data” contains the CO2 and water flux data along with the corresponding diffuse light fraction at the time of measurement from the ITEX shrub canopy project taken at Toolik Lake, Alaska in 2012. Each record is a single LiCor flux measurement made with LiCor 6400 photosynthesis system, with associated average pressure, temperature, PAR, water vapor, and other data such as NDVI and LAI measurements taken with a DeltaT SunScan wand under both direct and diffuse light conditions.
Summary of three methods used to estimate the Leaf Area Index (LAI) of 19 1m x 1m plots sampled with a point frame near the LTER Shrub plots at the Toolik Field Station in AK the summer of 2012. The methods used were: (1) exponential relationship between LAI and NDVI as measured above the canopy with a Unispec spetroradiometer; (2) Delta-T SunScan canopy analyzer held at 5 cm above the ground under both direct and diffuse light conditions; (3) pin-drop point frame tequnique. Where values have been averaged (such as for the NDVI and SunScan measurements), the standard deviation is given.
Leaf area index (LAI) measurements were taken with the Delta-T SunScan wand every 15 cm from the ground to above the canopy under both direct and diffuse light. conditions The data includes all outputs from the SunScan wand: time of measurement, transmitted light, spread of PAR sensors, beam fraction, and zenith angle.
Total and individual subsample species percent cover data for all plots where flux or point frame measurements were made in 2012 IVO the LTER Shrub vegetation plots at Toolik Field Station. All plots sampled were dominated either by B. nana or S. pulchra canopies. Cover estimates were made for the five most dominate functional groups using a 1m x 1m grid with 20cm2 blocks with each square representing four percent of the total area. Percentages represent absolute cover so do not sum to 100%.
A/Ci curve parameters and modeled carboxylation, electron transport, and triose-phosphate utilization efficiency rates from shoots clipped from low, mid, and the top of tall, shrub canopies dominated either by Salix pulchra or Betula nana species. Six shoots were harvested from each 1m x 1m plot, two from each level in the canopy. These plots were located near the LTER shrub plots at the Toolik Field Staion, AK for point frame measurements, and all measurements took place the summer of 2012.
Soil temperature at 5cm and 10cm depth [°C], volumetric water content (VWC) [%] and depth of thaw [cm] for 14 shrub canopy flux plots measured in vicinity of the Toolik Field Station, AK in 2012.
The percent carbon and nitrogen from leaves of shoots harvested from 1m x 1m point frame plots the summer of 2012 at Toolik Lake, Alaska. were measured on a ThermoScientific 2000. For each point frame plot, six shoots were harvested from upper, middle, and low sections of the canopy. The photosynthetic capacity of each shoot was analyzed with a LiCor 6400 infra-red gas analyzer by being run through a light response and A/Ci curve.
This file contains limited daily summaries of PAR, relative humidity, and temperature data monitored above, within, and below Betula nana and Salix pulchra shrub canopies at two locations near Toolik Lake, Alaska during the summer of 2012. The location of the PAR sensor and dataloggers were co-located with the LTER shrub plots (block 1 and 2), also used for the chamber flux and point frame measurements taken this same year.
14 1m x 1m shrub plots were sampled the summer of 2012 under direct and diffuse light conditions. Light response curves were measured under each light condition for each plot using a Li-Cor 6400 to measure net ecosystem exchange (NEP); these measurements were modelled using a saturatingMichaelis-Menton formula.
This file contains irradiance (PAR) and diffuse light data logged from a beam fraction (BF3) sensor near Toolik Lake, Alaska during the summer of 2012. The data comes from a compilation of automated datalogger readings as well as measurements taken during the field season in conjunction with the Delta-T SunScan wand to measure PAR in tall shrub canopies dominated by Betula nana or Salix pulchra species. The sensor was leveled and mounted to a 2m tripod in each location, and programmed to record instantaneous readings in 30 second to 5 minute intervals.
"2012_GS_PFandCH_GPS" contains GPS locations of all datalogger, 1m x 1m chamber flux and point frame plots sampled IVO Toolik Field Station in Alaska during the summer of 2012. The sorting variables (YEAR, DATE, SITE, GROUP, PLOT, TREAT, PLOT SIZE) are identical to those in other files with data collected that season. The main purpose of this file is for reference and as an aid in interpretation of data analyses and among-site comparisons.
Within-canopy PAR was measured with a Delta-T SunScan wand every 15 cm from the ground to above the canopy under both direct and diffuse light. The data includes all outputs from the SunScan wand: time of measurement, spread of PAR sensors, total irradiance, total diffuse light, and individual outputs of 64-PAR sensors on the SunScan wand. These measurements were taken for 1m x 1m chamber flux (n=14) and point frame (n=19) plots as well as sites four montitored remotely by PAR sensors located above, within, and below shrub canopies.
Leaf and plant tissue area and mass from shoots harvested from 19 1m x 1m point frame plots near Toolik Field Station, AK during the summer of 2012. Six shoots were harvested from each plot, two from each canopy layer: upper, middle, and low. Each shoot came from a different plant, and the species selected was based on the species dominant in that canopy layer. The leaf area and mass were used to correct A/Ci and light response curves taken on each shoot [data published separately].
This file contains PAR , relative humidity, and temperature data logged every five minutes from within, below, and above Betula nana and Salix pulchra shrub canopies at two locations near Toolik Lake, Alaska during the summer of 2012. The location of the PAR sensor and dataloggers were co-located with the LTER shrub plots (block 1 and 2), also used for the chamber flux and point frame measurements taken this same year.