The LTER moist acidic tussock (MAT) site was set up in 1989. The experimental design is four blocks of 5 x 20 meter plots with randomly assigned treatments within each block. Treatments include control (CT), nitrogen (N), phosphorus (P), and nitrogen plus phosplorus (NP). Fertilizer is added annually following snowmelt in June as 10 g/m2 nitrogen (as NH4NO3) and 5 g/m2 phosphorus (as triple superphosphate). Exclosure plots were set up at the MAT site in July 1996 on extra 5 x 20 meter plots within the four-block design of the 1989 LTER acidic tussock experimental plots. On each plot a 5 x 10 meter section was fenced with large mesh (4-inch square mesh) and within this fence, a 5 x 5 meter plot was fenced with a small mesh (1/2-inch square mesh). In each block two fenced plots were set up: a plot with no fertilizer and a plot with annual fertilization treatments as described above. Thus the treatments created are no fence, no fertilization (NFCT); small mesh fence, no fertilization (SFCT); large mesh fence, no fertilization (LFCT); no fence, N plus P (NFNP); small fence, N plus P (SFNP); and large mesh fence, N plus P (LFNP). Only plant species in NFCT, NFNP, SFCT, and SFNP were measured in 2004. The LTER dry heath (DH) site was also established in 1989 using the same methods at MAT in three block replicates. Exclosure plots were set up in 1996 using the same methods at MAT. The same plots were also used in plant species measurement in 2004.

Reference citations:
Gough, L., E.A. Ramsey, and D.R. Johnson. 2007. Plant-herbivore interactions in Alaskan arctic tundra change with soil nutrient availability. Oikos. 116: 407-418.

Sampling description:
Three individual plants of the dwarf shrub Betula nana in each plot in each community were selected and tagged early in the 2004 field season. Three individual live stems were tagged on each B. nana shrub. Stems that has one long, terminal shoot that originated the previous year were chosen, and the tag was placed at the bud scar for the previous year. At each sampling date, length of new shoot production, total shoot length, number of new long shoots, number of leaves, and number of flowers were recorded for each tagged shoot. Sampling was conducted weekly, beginning 14 June 2004 at MAT, and 16 June 2004 at DH.

Notes:
Some plots did not have a third B. nana individual, but are included in the data set.
If #SS, # LS, or # Leaves was not recorded, cells are marked with #N/A.
If #Ifl was not recorded, cells are marked with #N/A; all recorded #Ifl are new.
Sex of individuals shrubs were recorded if determined.
New Growth measures the individual lengths of new shoots in centimeters.
Total Length measures the total length of the tagged shoot in centimeters.