PERCENT COVER METHOD
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. Locations were preferentially chosen to represent tall shrub canopies (height > 70 cm) and to avoid the edge of vegetation stands or locations where the canopy appeared unhealthy, trampled, or patchy.

We split the 1m x 1m plots into 25 sub plots using a grid, then estimated percent cover of the five most common functional groups/species in each of the sub plots individually and then summed the percentage from each plot (representing 4% total cover) to obtain the total cover by functional group/species. For each measurement, at least two field technicians performed the estimates by species; the value recorded was the average of the two (or more) estimates. The total vascular plant cover for the entire plot is the sum of all species cover percentages; the total plant cover is the vascular plant cover plus moss cover. Percentages represent absolute cover, and thus they do not sum to 100%

Each spp is assigned a 6 letter code; the first 3 letters of genus and species name. SPP indicates the species is not known.

Where many graminoids were growing together it was often impossible to judge the individual percentages, so only the total for the growth form is given; the main species present are listed in the notes column.

The species or functional groups identified in the 1m x 1m point frame and chamber flux plots are are coded to match those collected by ITEX harvest plots from 2003 - 2009 as defined here:

SPECIES | CODE | FUNCTIONAL GROUP | COMMENTS
Betula nana | BET NAN | D |
Forb | FORB | F |
Grass or sedge - unidentified | GRAMMINOID | GRM |
Ledum palustre | LED PAL | E |
Moss - unidentified |MOSS |B |
Pedicularis species | PED SPP | F |
Potentilla species | POT SPP | F |
Salix glauca | SAL GLA | D |
Salix pulchra | SAL PUL |D |
Salix reticulata | SAL RET | D |net veined willow
Vaccinium vitis-ideae |VAC VIT |E |
Vaccinium uliginosum | VAC ULI | D | bog blueberry

Growth forms (functional groups) are abbreviated as follows:
D = deciduous shrub
E = evergreen shrub
F = forb
GRM = graminoid or sedge
B = bryophyte (mosses and liverworts)

#N/A refers to a value that was not recorded.