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University of Minnesota
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Methods for Experiment 070 -

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 number 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

Pocket gophers are trapped out of E070 as soon as they appear (very seldom).

Burning LTER Plots

All of the burning done within LTER experiments at Cedar Creek Natural History Area are done in late April or early May. Burn permits are issued to Cedar Creek Natural History Area for this time, and the following areas within Cedar Creek, by the Department of Natural Resources (headquarters in Cambridge, MN). In all cases, several people are on hand to help contain the fire. Tools used are "flappers", shovels and hand-pumped, portable water spray-cans. Drip torches containing a mixture of 1/3 gasoline and 2/3 diesel are used to start the fires. A truck carrying a high pressure water sprayer hooked up to a 125 gallon tank of water is always nearby. After the fires are burned out, any remaining hotspots are extinguished or moved to the center of the burned area to insure the prevention of wildfires.

125 gallon water tank and Minnesota Warmer Co. model KW125-7-10 utility sprayer.

Burning Methods

Starting in 1991, all of the plots in experiment E070 are burned each spring before the plants start growing. This is to destroy the litter so there is no litter effect. Each plot is surrounded by several feet of bare sand which functions as an effective fire break. The plots are set on fire, one at a time, using a drip torch. The truck holding the 125 gallon tank of water and several fire fighting tools are present in case of a fire escape, but these plots are so well contained (they are surrounded by aluminum flashing and bare sand) that this risk is minimal.

Fertilization Treatments

For experiments 55 and 70, the following nutrients are added twice each year, once in early May and once in late June:

Nutrient Amount
P2O5 18 g/subplot
K2O 18 g/subplot
CaCO3 18 g/subplot
MgSO4 18 g/subplot
Trace Metals 1/4 teaspoon/subplot


Each subplot is 1.44 m2. This will give each subplot a total of 25 g/m2 of each chemical per year.

Field Operations: Fencing

A belowground gopher fence (3 feet deep and 1 foot wide) and above-ground rodent/deer fence (6 feet tall) was built around the plots in 1989. Each plot was subdivided into 4 subplots with galvanized sheet metal (26 gauge, 48" x 12") in 1989.

Field Operations: Fertilization

Fertilizer is mixed and spread by hand twice a year, once in early May and once in late June. All plots receive the same fertilizer, with none of them getting any NH4NO3.

Field Operations: Mammal Trapping

Small mammals are trapped in the fall to discourage overwinter inhabitants. Pocket gophers are trapped out of the experiment as soon as they appear (very infrequently).

Field Operations: Watering

All plots are watered to receive at least 1.5cm/wk in April, May and October, and 2.5 cm/wk in June through September.

Field Operations: Weeding

All plots and aisles are routinely weeded to keep the area free of unwanted plants and future seed sources.

Treatment layout : trmte70

Species Treatment: LC=Lespedeza capitata, AC=Amorpha canescens, PP=Petalostemum purpureum, SS=Schizachyrium scoparium Seeds planted to a density of 2000 seeds/m2 or 1000 seeds/sub-subplot of each species. Treatment Codes 1 = LC seed on top of established SS 2 = AC seed on top of established SS 3 = No seed added to established SS 4 = PP seed on top of established SS 5 = AC seed vs SS seed 6 = LC seed vs SS seed 7 = PP seed vs SS seed 8 = LC seed vs AC seed vs PP seed vs SS seed 9 = AC seed 10 = LC seed 11 = Bare ground (no seeds added) 12 = PP seed

Field Identification Experiment Number Plot Number Subplot Number Sub-subplot Number SpeciesTreatment
E7012411
E7012423
E7012432
E7012444
E7012515
E7012527
E7012536
E7012548
E7012619
E70126210
E70126311
E70126412
E7022419
E70224211
E70224310
E70224412
E7022512
E7022523
E7022534
E7022541
E7022615
E7022628
E7022637
E7022646
E7032417
E7032428
E7032436
E7032445
E70325112
E70325210
E70325311
E7032549
E7032614
E7032623
E7032632
E7032641
E70424112
E70424211
E70424310
E7042449
E7042518
E7042527
E7042535
E7042546
E7042611
E7042622
E7042634
E7042643
E7052411
E7052423
E7052432
E7052444
E7052518
E7052526
E7052537
E7052545
E7052619
E70526212
E70526310
E70526411
E7062414
E7062423
E7062432
E7062441
E70625112
E70625211
E7062539
E70625410
E7062615
E7062626
E7062637
E7062648
E7072419
E70724212
E70724310
E70724411
E7072515
E7072526
E7072538
E7072547
E7072613
E7072624
E7072632
E7072641
E7082414
E7082421
E7082432
E7082443
E70825112
E70825211
E7082539
E70825410
E7082617
E7082625
E7082636
E7082648
E70924111
E7092429
E70924312
E70924410
E7092516
E7092527
E7092535
E7092548
E7092612
E7092623
E7092631
E7092644
E70102416
E70102425
E70102438
E70102447
E701025110
E701025211
E701025312
E70102549
E70102612
E70102624
E70102631
E70102643
E70112419
E701124212
E701124311
E701124410
E70112514
E70112523
E70112531
E70112542
E70112616
E70112628
E70112635
E70112647
E70122418
E70122426
E70122437
E70122445
E70122512
E70122524
E70122533
E70122541
E701226110
E701226212
E70122639
E701226411
E701324111
E701324212
E70132439
E701324410
E70132516
E70132527
E70132538
E70132545
E70132614
E70132622
E70132631
E70132643
E70142417
E70142428
E70142435
E70142446
E701425112
E701425210
E70142539
E701425411
E70142611
E70142622
E70142633
E70142644
 

Vegetation Sampling

Clip strips were 10cm wide and 50 cm long

1992: Clipped 25-35cm from left (middle), 5cm in from front and back
1993: Clipped 10-20cm from left, 5cm in from front and back
1994:
1995:
1996: Clipped 35-55 cm from left, 5 cm in from front and back
1997:
1998:
1999:
2000:

Sampling Problems in E070:

1992: none

1993: none

Vegetation Sampling Methods

E070 is sampled annually. Each time it is sampled, the sample strip is located in a different place. Sample size is 10cm X 50cm. A wooden frame was made to aid in location of the sample strip. The frame was layed down with the edge in contact with the subplot edge. The strip was then marked with toothpicks or flags (depending on vegetation density). After the frame was removed, the strip was clipped between the toothpicks or flags. This insured consistent sample size and placement in each subplot. Sampling methods, except for the use of the 3m aluminum pole, are described in above ground vegetation sampling methods.

In 1992 and 1993, reproductive structures were clipped off individual plants dried and weighed separately to determine allocation to reproduction. This was done early in the monoculture plots.

Watering Methods

All plots receive at least 1.5cm/week of water in April, May and October and 2.5 cm/week in June through September. If the plots receive this water from natural rainfall, then no supplemental watering is needed. When watering is needed, it is done using a system of hoses set up in the field. A black irrigation pipe, 3 inches in diameter, is hooked up to the pump. This extends out to the E026 area where the 3-inch hose is divided into two 2-inch hoses. One part goes toward the E026 (and E071) plots (the other toward E055, E069, E070). From this hose, several regular garden hoses are connected. Gardena Excellent Oscillating Sprinklers, model 6968, are attached to these hoses. These sprinklers are purchased at Sears and made at Gardena, Inc., 6031 Culligan Way, Minnetonka, MN 55345. Three or four hoses/sprinklers are used at one time. Any more than this reduces the water pressure enough so the sprinklers will not work. The sprinklers are rotated in order to reach all of the plots.