Arthropod Pitfall Traps-III in 5x1 grid at LTER II NPP sites

Data Access: 

Unrestricted

Dataset status: 

Study number: 

8

Data set ID: 

2100008001

Original investigator: 

John Anderson

Abstract: 

Objectives. Desertification is hypothesized to have
altered the spatial and temporal availability of resources
required by the biota. Results of desertification on the

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
will be collected for the duration of the LTER program in
order to provide data to test these hypotheses.
Data for arthropods captured in pitfall traps on LTER
III consumer plots at 2 month intervals. Data includes
order, family, genus, species, and number.

Methods: 

lab data sheets

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.

Quality assurance: 

SAS program will be used to analyze data

Additional information: 

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.

Maintenance: 

Typically, every 2 months. However, 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.

Signature dataset: 

LTER Core Area(s): 

Data category: