Methods:
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Arthropod pitfalls were established in January of 1995 at the start of LTER III; this design is significantly different from the pitfalls of LTER II, when lizards and arthropods were collected in the same traps. The newer arthropod pitfalls consisted of a small tin can (buried flush with the soil surface) in which a plastic cup (10 oz.) fits snugly. The cup was filled (about 3/4 full) with propylene glycol (the "non-toxic" antifreeze, Sierra brand) which captures and preserves any arthropods that stumble in. A ceramic tile shaded the trap, supported by 4 nails sticking about 1" above the ground.
To minimize rodent damage to the pitfalls, chicken wire fences with lids were installed around each trap. Unfortunately, rodents or lizards smaller than the holes in the chicken wire continued to cause significant damage to the traps after the exclosures were added, so in June 1996, hardware cloth collars were also added to the pitfalls. These collars were squares about 10" on a side with a hole cut in the center for the can & cup combination. Additional holes were cut for any grass clumps surrounding the pitfalls to minimize disturbance to the vegetation. They were buried under a thin layer of soil. Because of concern about the numbers of vertebrates (small rodents and lizards) being caught in the pitfalls, in February 1996, 1/4" hardware cloth ladders (5 " long x 3/4 " wide) were added to the traps. It was hoped that rodents and lizards would be able to escape, while arthropods would not (due to the strength of the surface tension of propylene glycol).
The traps were continuously open, and the arthropods in them collected every 2 months. If time permitted, during the month in between collections, the traps were checked once, to top off the propylene glycol, and repair any wind/rain/rodent/coyote/vandal damage. During windy seasons, the traps at M-RABB and M-NORT sometimes needed to be collected monthly because of large volumes of sand collecting in the cups. This occurred if cups became close to 1/2 full of sand in one month's time. There are five arthropod pitfalls at each of the NPP study sites, excluding the playas. The five traps are in a line, 15m from each other, marked with orange pin flags. The following list tells where the line of traps for each site was, relative to the NPP grid: C-GRAV=NW corner, C- SAND=south side, C-CALI=SW corner, G-SUMM=NE corner, G- BASN=east side, G-IBPE=NW corner, M-WELL=east side, M- RABB=west side, M-NORT=south side, T-TAYL=east side, T- EAST=east side, T-WEST=south side. In addition, from January 1995 to March 1997, at G-IBPE and C-SAND, there were 12 extra pitfalls, used in a cross-site study for comparison to data from the Sevilleta and Bandelier. These extra pitfalls were in 4 sets of 3, distributed on all sides of the NPP grid (see maps). Each trap was numbered for identification, and these numbers were written on the underside of the tile over each trap.
Additional files
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1. 'arthropodcodelist.txt' is a text file describing the taxonomic codes used in the data file (order, family, genus, and species columns). The value 'XX' in the taxonomic codes indicates unknown.
2. 'arthpit3.dsd' is a metadata file created during the time of the study. It contains additional metadata that may not have been placed into the current EML file for this data package.
