|Data by Research Category|
Dataset: Arthropod Pitfall Trap Collections at NPP Sites on the Jornada Experimental Range, 1996-2001
Objectives. Desertification is hypothesized to have altered the spatial and temporal availability of resources required by the biota. Results of desertification on the Jornada include changes to shrub dominated communities and major soil changes. We hypothesize that these shifts in vegetation have changed resources temporally for many of the consumers. If grassland systems respond to rainfall without significant lags, but shrub systems do not, then consumer species should reflect these differences. In addition, shifts from grassland to shrubland results in greater structural heterogeneity of the habitats. We have hypothesized that consumer populations, diversity, and densities of some consumers will be higher in grasslands than in shrublands. Diversity and/or densities are hypothesized to be related to the NPP of the sites. Data for arthropods captured in pitfall traps on LTER III consumer plots at 2 month intervals. Data includes order, family, genus, species, and number. This data collection has been completed.
Jornada LTER III arthropod pitfalls are located at each of the NPP study sites, excluding the 3 playas. (T-WEST, T-EAST, T-TAYL, M-NORT, M-RABB, M-WELL, G-IBPE, G-BASN, G-SUMM, C-SAND, C-CALI, C-GRAV) The following list gives the location for the line of traps for each site 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 wide M-NORT south side T-TAYL east side T-EAST east side T-WEST south side In addition, there were 12 additional pitfalls at G-IBPE and C-SAND which were used in a cross-site study for comparison to data from the Sevilleta dn 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 are written on the underside of the tile over each trap. The 12 additional cross-site study pitfall traps were terminated in March 1997.
lab data sheetsMethods:
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 new arthropod pitfalls consist of a small tin can (buried flush with the soil surface) in which a plastic cup (10 oz.) fits snugly. The cup is 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 shades 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 are 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 are 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 is hoped that rodents and lizards will be able to escape, while arthropods won't (due to the strength of the surface tension of propylene glycol). The traps are continuously open, and the arthropods in them collected every 2 months. If time permits, the month in between collections, the traps should be 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 may need to be collected monthly because of large volumes of sand collecting in the cups. Collect these sites monthly if cups become close to 1/2 full of sand in one month's time. Data may be lost if the cups are allowed to fill completely with sand. 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 is, 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. Beginning 08/19/1998 data is being collected of the condition of each pitfall trap, whether a sample was collected, and the number of vials collected per trap. CONDITION CODES USED: good GD low fluid, but okay LO surface solid(bugs/soil/litter) SS cup was washed over by water WO trap filled with water or diluted FW dead animal in trap DA litter in/extending out of trap LL rim elevated >1cm: 30% 30 rim elevated >1cm: 60% 60 cover resting on trap rim CR part/all of cover on soil CS down cover blocking access(CS)n% n% trap disturbed by animals TD trap exposed to the sky EX trap not found NF rim elevated by soil erosion ER other(state in comments) OT slime factor SF grasshopperage 50% G50 grasshopperage 30% G30 COLLECTION CODES: sample taken ST Maintenance Equipment trowel propylene glycol (Sierra brand antifreeze) spare tiles, nails, cups, cans and ladders Collection Equipment maintenance equipment (above) 75% alcohol (3 liters + squirt bottle) collection vials with labels (see sample labels at end of Procedures) tweezers, chopstick, fork strainers (5) funnel Ziploc bags (pint size or smaller) Maintenance Procedure 1. Lift tile off each trap and check that soil is flush with cup edge. If rodents, wind, water, etc. have pulled soil away, replace it. Gravel and rocks can be used to discourage digging and "pave" the area around the cup. (This "paving" is what we tried before installing the hardware cloth collars; hopefully, we won't have to deal with much more of this sort of damage.) 2. Top off the propylene glycol (if necessary) so cup is about 3/4 full. 3. Keep a record of all traps requiring attention. Collection Procedure 1. Remove cup from trap, and dump into strainer placed over spare tin can & cup combination. Thoroughly rinse the pitfall cup with alcohol from squirt bottle; use fork and forceps as necessary to clean out cup. 2. Return strained propylene glycol to cup, top off as necessary, and replace in trap. Do trap maintenance as needed (record all damage to traps). 3. Use funnel to transfer sample to collection vial.*** Knock strainer firmly against funnel to get tiny --> microscopic things off strainer into funnel. Chopstick works well to push arthropods through neck of funnel with small to medium sized collections. If there's more than will fit into one collection vial, use forceps to pack large insects into vials first, then squeeze the rest in around them. (Make sure to add a label to any extra vials used.) Rinse funnel with alcohol into vial, and top off vial with alcohol as necessary. *** The collection kit set up by D. Lightfoot has enough strainers to go into a site (except C-SAND and G-IBPE), collect all 5 traps, and come out and do the transferring to vials back at the truck. Make sure to keep the strainers in order so you know which trap they came from, and use the bungie cords to hold them in place while carrying the kit. 4. The strainers should be knocked soundly against something solid (e.g. a truck tire) to get any remaining mites etc. off them before using them at the next site. The funnel, forceps, chopstick, and fork should be rinsed will with alcohol before use at a different site. Special Procedure for Sandy Traps at M-RABB and M-NORT: Save all sand that accumulates in cups. If volume of sand (not arthropods) would require more than 1 vial, use a ziploc to save the sand. First decant off any free- floating arthropods in propylene glycol (and place in vial as above), then transfer the sand into a ziploc (with a label). Sand will have absorbed plenty of propylene glycol, so no alcohol or propylene glycol needs to be added to the sand for preservation. Sample Labels for Collection Vials C-SAND A 1 C-SAND A 2 C-SAND A 3 C-SAND A 4 C-SAND A 5 16FEB1996- 16FEB1996- 16FEB1996- 16FEB1996- 16FEB1996- 18APR1996 18APR1996 18APR1996 18APR1996 18APR1996 C-SAND B 1 C-SAND B 2 C-SAND B 3 C-SAND C 1 C-SAND C 2 16FEB1996- 16FEB1996- 16FEB1996- 16FEB1996- 16FEB1996- 18APR1996 18APR1996 18APR1996 18APR1996 18APR1996 C-SAND C 3 C-SAND D 1 C-SAND D 2 C-SAND D 3 C-SAND E 1 16FEB1996- 16FEB1996- 16FEB1996- 16FEB1996- 16FEB1996- 18APR1996 18APR1996 18APR1996 18APR1996 18APR1996 C-SAND E 2 C-SAND E 3 C-GRAV 1 C-GRAV 2 C-GRAV 2 16FEB1996- 16FEB1996- 16FEB1996- 16FEB1996- 16FEB1996- 18APR1996 18APR1996 18APR1996 18APR1996 18APR1996 C-GRAV 3 C-GRAV 4 C-GRAV 5 16FEB1996- 16FEB1996- 16FEB1996- 18APR1996 18APR1996 18APR1996 Laser jet printer ink is not alcohol soluble and works well for these labels. If additional labels are needed in the field, write (in pencil--many other inks are alcohol soluble) the pitfall number (include the site!) and collection date onto a small square of the heavy bond paper kept in the drawer of the collection kit. You only need enough information on the extra labels to match them up with the complete labels when the samples are processed.
Typically, every 2 months. However, during windy seasons, the traps at M-RABB and M-NORT were collected monthly because of large volumes of sand collecting in the cups. This study is complete.
SAS program will be used to analyze data