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University of Minnesota
College of Biological Sciences
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Methods for Experiment 061 -

Above ground vegetation sampling

Aboveground vegetation is collected in narrow strips to limit the effect of the sampling. Benches are used to avoid trampling the surrounding area. A 3m long fiberglass pole is placed along the ground next to the appropriate site of the present years sample strip. This is used as a guide to keep the 3m long sample strip straight. Vegetation is cut using a Sears/Craftsman Extra Heavy Duty Cordless Electric Grass Shears, model # 240.79672. These clippers have blades which are 10cm wide, making it easy to clip a strip of that width. The clippers are powered by 6-volt motorcycle batteries.

All vegetation that is rooted in the 10cm wide strip is cut 1-2cm from the soil surface. The vegetation and litter that was in the strip is collected. Care is taken to clip and collect only that material which is actually in the 10cm wide strip, not entire plants that may lay across the strip.
If there is a gopher mound in the plot where the clip strip is, the strip is moved in towards the middle of the plot until it is no longer over a gopher mound. The new position of the clip strip is then recorded.

Animal Sampling Methods

Grasshoppers are sampled within both BEX (birds excluded) and BAL (birds allowed) plots. Grasshoppers are sampled by two people with butterfly nets. A plot was swept for 15 minutes three times in succession, separated by 15 minute rest periods. For a list of species and their taxon codes, see file ghoppers.lst.

Field Operations: Fertilization

Fertilizer is mixed and spread by hand twice a year, once in early May and once in late June. Each plot gets the fertilizer mixture specified by its fertilizer treatment code.

Field Operations: Netting

Bird netting (2.5 cm mesh) was stretched over a framework to exclude birds in plots receiving the BEX (bird exclusion) treatment.

Sampling for B061

In 1989, after 1-2 months, netting was removed and grasshoppers were sampled within both BEX and BAL plots. The plots were sampled August 16, 17 and 18. Grasshoppers were sampled by two people with butterfly nets. A plot was swept for 15 minutes three times in succession, separated by 15 minute rest periods.

After grasshoppers were sampled, vegetation was sampled. Within each 9m x 9m plot, three 0.1m x 3m strips were clipped, sorted to species, dried at 45

Vegetation and grasshopper sampling in 1990 was similar to that in 1989. In 1991, grasshoppers were sampled, with sweep nets, on August 21, 22 and 23. Vegetation was sampled by clipping three, 3 x 0.1m strips in each macroplot. This was done on August 26 and 27. Soil was sampled on September 9 and 10. Three soil cores were taken from each macroplot.

Treatment layout : trmte61

Note: Bird treatment- BAL= birds are allowed in plot, BEX = birds are excluded.

Field Number Experiment Number Macroplot Number Nitrogen Treatment Ammonium Nitrate(34-0-0) addition(g/m2/yr) Bird Treatment
B612I0BAL
B612I0BEX
B613I0BAL
B613I0BEX
B614G50BAL
B614G50BEX
B616I0BAL
B616I0BEX
B617G50BAL
B617G50BEX
B6110G50BAL
B6110G50BEX
 

Vegetation Sampling Methods

E061 is in field B. The plots in this experiment were sampled on August 16-18, 1989. Within each 9m x 9m plot, three 10cm x 3m strips were clipped.

Sample size is 0.1m x 3m.