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
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.
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].