Plots are setup as indicated below, with annual fertilization treatments of 10 g/m2 Nitrogen (as NH4NO3) and 5 g/m2 Phosphorous (as triple superphosphate) for all N, P and NP treatments. Greenhouses and shade houses are set up annually in early June and removed in mid-August.

Sites:

1981 Moist Acidic Tussock

Plots were setup in June 1981 with annual fertilization treatments of 10 g/m2 Nitrogen (as NH4NO3) and 5 g/m2 Phosphorous (as triple superphosphate) were applied. Greenhouses and shade houses were annually set up in late May or early June and removed in the end of August or early September. Greenhouses and shade houses were discontinued in 1989. There are 4 replicate blocks, each containing 1 replicate of each of the following treatments.
 Control (CT)
 Fertilized (NP)
 Greenhouse (GH)
 Greenhouse fertilized (GHNP)
 Shade (SH)

1989 Moist Acidic Tussock Tundra
      Blocks 1-4
                   (CT, N, P, NP, GH, GHNP, Shade, and Shade NP treatments)
                    Treatments began summer of 1989. Plots size are 5x20 meters
                         plot/treatment except for GH, GHNP, Shade, and Shade NP which are 2.4 x 4.9 meters.
                  
                 Exclosures of large mesh and small mesh fences:
                  (EXCT fence, EXCT no fence, EXNP fence and EXNP no fence)
                    Treatments began in 1997. Plot size are 5x10 meters.
                   All fences are large mesh with an inner 5x5 meter small mesh fence.
    
Moist Non-Acidic Non-Tussock Tundra
      Blocks 1-3 (CT, N, P and NP treatments)
                    Treatments began summer of 1997. Plots size are 5x20 meters
                         plot/treatment.
   

Moist Non-Acidic Tussock Tundra
      Blocks 1-3 (CT, N, P and NP treatments) (GH and GHNP treatments are on block 1 and 2 only)
                    Treatments began summer of 1997. Plots size are  5x20 meters
Wet Sedge
        Block 1 - Toolik Inlet (CT, N, P, NP, GH, GHNP, and Shade treatments)
                     Indicated as "Block 1"
                    Treatments began summer of 1989; one 5x10m
                         plot/treatment
        Block 2 - Toolik Outlet (Same treatments)
                     "Block 2"
                    Treatments began summer of 1989; one 5x10m
                         plot/treatment

Low Fertilization - in 2006, a new set of experimental treatments were established in MAT near the earlier plots described above. These include a gradient of fertilization treatments that receive nitrate or ammonium alone, or receive N and P additions with 0.5, 1, 2, 5, or 10 g N added with half of that amount added as P. An additional set of plots were set aside upon establishment for future experiments, and are noted as H.

 A total of 8 measurements were made with a stainless steel probe. All measurement made in inter-tussock mossy area; not wet hollows. Depths for each plot were taken along the 20 meter sides every at 2.5, 7.5, 12.5, 17.5 meters. For greenhouses and shade houses one depth was taken between every set of rafters (every 1.2 meters).

No measurements were made in the shrub or heath experimental plots due to gravel and rocks.

NOTES AND COMMENTS:  The tussock greenhouses and shade houses were measured after the plastic and shade cloth were removed.

2006 Measurements were not made in Non- Acidic sites because thaw was deep enough that a rock layer was reached. 
2008 No measurements in Non acidic tundra.
2009 Thaw in the low fertilization plots were made.

2016 Seasonal measurements but only 5 reps were done. 

2017-2018 only 1989 Moist Non-Acidic Tussock Tundra and 2006 Low fert Moist Non-Acidic Tussock Tundra were measured.  For other sites it has become difficult to distinguish rocks from frozen soil with a steel thaw probe.