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Methods for Experiment 002 -

Burning LTER Plots

All of the burning done within LTER experiments at Cedar Creek Ecosystem Science Reserve 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

In the spring of 1992, 3 randomly chosen replicates of each nutrient treatment of E002 in field B were chosen to be burned each spring. In preparation for burning, the perimeter of groups of plots to be burned is mowed using a lawn mower. The cuttings and litter remaining are raked into the area to be burned. This firebreak is then reinforced by wetting the cropped vegetation with a high pressure water hose attached to a 125 gallon water tank. A backfire is started to widen the firebreak. A drip torch is then used to start the groups of plots (one at a time) on fire. For a list of burn treatments for each plot, see file trmte98. On May 5, 1995, a wildfire burned all plots in experiment 002 in field B.

Field Operations: Burning

Starting in 1992, 3 replicates of each nutrient treatment were burned in field B each spring. These 27 plots are experiment E098. Plots 1, 2, 3, 5, 8, 9, 11, 16, 17, 19, 30, 31, 32, 33, 35, 36, 41, 42, 43, 44, 45, 47, 48, 50, 51, 53, 54 On May 5, 1995, a wildfire burned all of the plots in experiment E002 in field B.

Field Operations: Fencing

The plots in experiment 002 are enclosed by a fence to exclude mammalian herbivores. The fencing remained until the fall of 2004, when it was removed completely. Galvanized welded-wire hardware cloth with 6mm x 6mm openings was buried to a depth of 84cm. Additional hardware cloth extends 60cm above the ground, and poultry netting extends to 1.8m above the ground. During the summer of 1986, aluminum flashing was placed in the ground to a depth of 12 inches. This flashing surrounds each plot in each field, keeping the plants from spreading between plots by belowground vegetative reproduction. The aluminum flashing is placed 12 inches from the edge of each plot.

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. In the spring of 1992, 3 randomly chosen replicates of each fertilizer treatment in field A and C were chosen to receive no more fertilizer. These 27 plots in each field are experiment E097. See treatment details for E097 for a listing of plots which received no further fertilizer.

Layout of Plots

Microplot Fertilization Treatments

Some changes and/or additions occur from year to year for some experiments. These changes are listed below. Unless specific experiments are mentioned, these differences apply to all experiments in a category. In 1982, 30ml of each stock solution was combined with 16.8g citric acid, brought to a total volume of 1 liter, and autoclaved to dissolve. 1.5ml of this solution was added to 30ml of silica sand, mixed and dried. In 1983, 60ml of each stock solution was combined with 25g of EDTA brought to 1 liter, and autoclaved to dissolve. 1ml of this solution was added to 10ml of sand and added to each plot. In 1984, 60ml of each stock solution was combined with 25g of citric acid and brought to 1 liter. In 1985, the first fertilization for experiments 1 and 2, Treatment F received an extra 23 g/m2 of CaCO3 Treatment G received an extra 118.5 g/m2 of CaCO3 Treatment H received an extra 132.5 g/m2 of CaCO3 In 1985, between fertilizations for experiments 1 and 2, Treatment G received 137.5 g/m2 of CaCO3 Treatment H received 206.25 g/m2 of CaCO3 In 1985, the second fertilization for experiments 1 and 2, Treatment F received an extra 23.0 g/m2 of CaCO3 Treatment G received an extra 252.7 g/m2 of CaCO3 Treatment H received an extra 441.1 g/m2 of CaCO3 In 1985, the first fertilization for experiment 4, Treatment E received no CaCO3 Treatment G received an extra 45.5 g/m2 of CaCO3 In 1985, both fertilizations for experiments 8, 9, and 11, Treatment F received an extra 23 g/m2 of CaCO3 Treatment G received an extra 43.5 g/m2 of CaCO3 Treatment H received an extra 57.5 g/m2 of CaCO3 In 1989, lime was added to adjust pH to the following treatments in the spring: Quantities of lime stone (g/plot):

In the fall of 1989, each plot receiving treatments B, C, D, E, F, G and H in field D of experiment 1, received 1067g of lime to adjust pH.

Microplot Fertilization Treatments

The "microplot" fertilization treatments are used in experiments 1, 2, 4, 8, 9, 11, 23, 25, and 52. Experiments 5, 6, 28, 36,53,97, 98 and 100 are conducted within plots that are fertilized and should be treated as part of the fertilized plot. There are nine treatment levels, assigned a letter A through I. This is also equivalent to the numeric labels 1 to 9. Treatment levels A through H differ in the amount of NH₄NO₃ added. Treatment I is a true control and receives no nutrients. The nutrients are applied twice a year, once in early May and once in late June. An exception is experiment 25 where time of application is experimentally manipulated. Not all experiments use all possible treatments. Nutrients are given in g/m2 for each fertilization; plot area and treatments used follow the nutrient lists. Treatment A to H receive the following base nutrients:

The description for making trace mineral sand is at the end of this section. The amount of NH₄NO₃ fertilizer added at the different treatment levels is:

These rates are added twice a year. Actual annual N addition is calculated as: 0.34%N * rate (g/m2) * 2 times/year The trace mineral stock solutions are made by adding the following grams of reagent to 1000 ml of water: CuSO4*5H2O 9.8 g ZnSO4*7H2O 22.0 g or ZnCl2 10.5 g CoCl2*6H2O 10.0 g MnCl2*4H2O 180.0 g Na2MoO4*2H2O 6.3 g H3BO3 6.0 g The trace metal solution is made by combining 120ml of each stock solution, adding 67.2g of citric acid dissolved in deionized water and adding deionized water to bring the volume to a total of 2 liters. The working solution is then autoclaved to chelate the trace metals. The size of the plots and treatments used for each experiment are:

Treatment layout for E002

Nitrogen treatment code 1 through 9 are equivalent to treatment codes A through I, respectively.

Color codes of rebars used to mark treatments in E002

ahve002 - 2018 broad soil chemistry

soil analysis

A subsample (~80-100g) from each plot was homogenized by grinding the soil with two steel beads (Daisy Premium 3/8??? steel slingshot ammo) with 90 minutes of vigorous shaking using a paint shaker. Approximately 20 (18-25) mg of ground, homogenized soils were then packed into 5 x 9 mm tin capsules for carbon and nitrogen analysis using dry combustion gas chromatography on an Elemental Analyzer (Costech ECS 4010 CHNSO Analyzer, Valencia, California, USA) calibrated with the analytical standard, atropine (C 17 H 23 NO 3 ). 20g of the ground, homogenized soils were sent to Waypoint Analytical (Memphis, TN, USA) to measure major nutrients, micronutrients, soil pH, organic matter, cation exchange capacity, and texture of the soil (percent sand, silt and clay; only measured in the Control Plots). Phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, iron, manganese, zinc, and sodium (in parts per million) were measured using the Mehlich-3 method. Soil pH was measured with a water pHmeter on a 1:1 soil:water suspension. Cation exchange capacity (CEC), reported here as meq/100 g (milliequivalents of charge per 100 g of dry soil), is a measure of the capacity of soil surfaces to retain cations and is used as an indicator of quality and productivity of the soil. CEC was calculated using the ppm of Ca, Mg, and K reported from the Mehlich-3 method using the following relationship: CEC = (ppm Ca / 200) + (ppm Mg / 120) + (ppm K / 390)). Soil percent organic matter was measured using the Loss on Ignition (LOI) method (combustion for two hours at 400 o C). Values of organic matter reported here were not treated with acid prior to combustion. Texture was measured using the hydrometer method. In brief, the soil sample was shaken with Sodium Hexametaphosphate (HMP) solution, and then transferred to a settling cylinder and mixed. The percent sand, silt, and clay particles were calculated from hydrometer density readings taken at 40 seconds and two hours.

lpe002 - Percent light penetration

Light Penetration

Readings were taken .5m from the front and back of each plot. The distance from the left or right edge varied from year to year. If light readings were taken before the vegetation was sampled that year, the light readings were taken in the location of the clip strip. If light readings were taken after the vegetation had been clipped, the location of the light readings was moved to one side, or the other, of the clip strip so the bare spot would not affect the readings. Usually, a set of readings were taken from the front of the plot and a second set was taken from the back of the plot. The date, time, field, plot, side (left or right), front or back, distance from the side of the plot, range value (before 1988) and the display reading were all recorded for each measurement. If there was a gopher mound where the light readings should be taken, the sensor was moved in from the edge of the plot until it is no longer over a gopher mound. This was then recorded on the data sheet.

Light Penetration Instrumentation

From 1982 to 1988, light meter readings were taken using a Li-Cor, Inc. Integrating Quantum/Radiometer/Photometer, model LI-188B. Two people were needed to take light readings with this system. One would hold the control box and record data and the other would hold the light sensor. The batteries would be checked before starting each session. If the batteries were OK, they would proceed to take readings. The sensor was connected to the control box by a relatively short cord, so the two people taking readings were required to stay close together. When taking readings, it was necessary to get a range value for each light value entered. If the integrating time of 1 second was not sufficient, it was increased to 10 seconds. This was also recorded. In 1989, two new light meters were acquired. These are SF Sunfleck Ceptometers, model SF-40 (40cm probe). They were purchased from Decagon Devices, Inc., P.O. Box 835, Pullman, WA 99163. One person can easily handle a ceptometer alone. This makes is possible for three people to get the readings done more quickly and easily. One person records data while the other two take readings from the plots simultaneously. No range values are needed. To take readings a person needs to select function #1 (PAR readings), position the probe (see below) and press ``A' (read value). More than one reading can be taken and then averaged by pressing a certain sequence of letters (A, A, B, B, A). Measurements are taken within a 4 hour period, 2 hours on either side of solar noon. (Solar noon is half way between sunrise and sunset; it is not 1200 hours). Solar noon is at 1315 hours, Central Daylight Time. Samples are taken between 1115 hours and 1515 hours. Measurements are not taken when the plot being sampled is shaded. Light readings are done when the sky is clear, whenever possible. If a cloud passes over the plot being sampled, assistants wait for the cloud to pass before taking the readings. If the sky is mostly cloudy, light meter readings are not taken. Two measurements are taken in each plot. Each measurement consists of one reading above the vegetation and a second reading at ground level. Both values are taken to get the percent of sunlight above the vegetation that reaches ground level. In taking the above vegetation reading, the sensor must be kept level, held high above all vegetation, kept out of the shade (of plants and people) and it must be clean. When taking the below vegetation reading, at ground level, the sensor must be kept level, out of the soil and out of the shade created by people. In 1991, light meter readings were only taken in E026 and E055. Light profiles were taken using an A-shaped frame made of aluminum. Wires were strung across the frame at 10cm intervals. The frame was placed over the subplot being metered. A reading was taken over the top of the frame, and then at each 10cm level, by placing the light meter across the wires, starting at 90cm above the ground. Readings were taken every 10cm down the frame and again at ground level. Light Data Transformations: Light readings are transformed to obtain percent light penetration which represents the percent of light above the vegetation that reaches the ground surface. In cases where the experiment involves shading, another variable is computed to reflect the percent of sun light that reaches above the canopy. This variable is called light available. In the case of absence of artificial shades, the latter is set to 1. percent light penetration = ( Light below canopy / Light above canopy ). percent light available = ( Light below shade / Light above shade ).

mse002 - Small mammal abundance

Animal Sampling Methods

Small mammals, including mice, voles and pocket gophers, are trapped out of E001 in fields A, B, C, and D. The fence around each of these fields is designed to keep these small mammals out, but some get in regardless. The mice and voles are trapped out of the fields by using Victor snap traps baited with a mixture of peanut butter and oatmeal. Between 50 and 75 traps are set in each field (only 25 in D). This is most often done in the spring and fall. The traps are checked the day after they are set. Trap victims are identified and the numbers of each are recorded. The bodies are disposed of outside of the fields. In the middle of the summer, victims are quickly eaten and often all that is left behind are bones. These are not identified, but counted as skeletons or skulls. The pocket gophers do more damage, but they are more difficult to trap. Underground tunnels are located by poking a rebar into the ground surrounding a fresh gopher mound. When a tunnel is found, a hole is dug down to it and traps are set in place. Two or three traps may be set in a tunnel system if the hole is dug into a branching tunnel. Traps used are DK-1 Gopher and Mole Traps made by P-W Mfg. Co., 610 High Street, Henryetta, OK 74437 (918) 652-4981. Sometimes a piece of raw potato is used as bait. The hole is then plugged and covered so no light or air gets into the tunnel system. This would make the gopher suspect that something was wrong and it would backfill the tunnel, burying the traps. Traps are checked every second or third day in the summer, and once or twice a week in the spring and fall. Once a gopher is trapped out of a tunnel system, poison pellets are put down the tunnel in case there is a second gopher in the sutem or if another one moves in soon. Cyanide gas and sulphur gas have also been used to kill gophers, but there is no direct evidence of gopher death due to these gases. Trapping seems to be the most effective way to get rid of them. After the gophers are trapped out, the mounds are removed from the plots, and any buried and flattened vegetation is unburied and unflattened. This is done as soon as possible to keep the plants from dying. The locations of gopher mounds and trapped gophers are recorded.

Field Operations: Mammal Trapping

Field Operations: Mammal Trapping Small mammals are trapped as often as possible to keep the resident population low. Pocket gophers are trapped out of the fields as soon as they appear. Gopher mounds are then removed and vegetation is unburied.

ple002 - Plant aboveground biomass data

Listing of location of aboveground vegetation sampling in E002 Field C

Year Clipped Area 1982 Clipped 0.25 to 0.35m from left, 0.5 to 3.5m from bottom 1982 Clipped 3.65 to 3.75m from left, 0.5 to 3.5m from bottom 1983 Clipped 0.5 to 0.6m from left, 0.5 to 3.5m from bottom 1984 Clipped 3.4 to 3.5m from left, 0.5 to 3.5m from bottom 1985 Clipped 0.75 to 0.85m from left, 0.5 to 3.5m from bottom 1986 Clipped 3.15 to 3.25m from left, 0.5 to 3.5m from bottom 1987 Clipped 0.9 to 1m from left, 0.5 to 3.5m from bottom 1988 Clipped 3 to 3.1m from left, 0.5 to 3.5m from bottom 1989 Clipped 0.35 to 0.45m from left, 0.5 to 3.5m from bottom 1990 Clipped 3.55 to 3.65m from left, 0.5 to 3.5m from bottom 1991 Clipped 0.6 to 0.7m from left, 0.5 to 3.5m from bottom 1992 Clipped 3.3 to 3.4m from left, 0.5 to 3.5m from bottom 1993 Clipped 3.65 to 3.75m from left, 0.5 to 3.5m from bottom 1994 Clipped 0.25 to 0.35m from left, 0.5 to 3.5m from bottom 1996 Clipped 0.5 to 0.6m from left, 0.5 to 3.5m from bottom 1997 Clipped 3.4 to 3.5m from left, 0.5 to 3.5m from bottom 1999 Clipped 3.15 to 3.25m from left, 0.5 to 3.5m from bottom 2000 Clipped 0.75 to 0.85m from left, 0.5 to 3.5m from bottom 2002 Clipped 2.55 to 2.65m from left, 0.5 to 3.5m from bottom 2004 Clipped 1.90 to 1.80m from right, 0.5 to 3.5m from bottom Sampling Discrepancies in E002 Field C Year Sampling Discrepancy 1982 Plot 14 112 missing weight 1983 none 1984 none 1985 none 1986 none 1987 none 1988 none 1989 none 1990 none 1991 none 1992 none 1993 Plot 32 clipped at 3.05-3.15m from left side to avoid an ant mound 1994 Plot 28 clipped at 1.00-1.10m from left to avoid a gopher mound 1996 none 1997 Plot 35 clipped at 3.25m from left 1999 none 2000 none 2002 none 2004 Plot 8, 19 clipped at 1.60-1.50m from left

Location of aboveground vegetation sampling in plot (4x4m) for E002 Field A

Listing of location of aboveground vegetation sampling in E002 Field A Year Clipped Area 1982 Clipped 0.25 to 0.35m from left, 0.5 to 3.5m from bottom 1982 Clipped 3.65 to 3.75m from left, 0.5 to 3.5m from bottom 1983 Clipped 0.5 to 0.6m from left, 0.5 to 3.5m from bottom 1984 Clipped 3.4 to 3.5m from left, 0.5 to 3.5m from bottom 1985 Clipped 0.75 to 0.85m from left, 0.5 to 3.5m from bottom 1986 Clipped 3.15 to 3.25m from left, 0.5 to 3.5m from bottom 1987 Clipped 0.9 to 1m from left, 0.5 to 3.5m from bottom 1988 Clipped 3 to 3.1m from left, 0.5 to 3.5m from bottom 1989 Clipped 0.35 to 0.45m from left, 0.5 to 3.5m from bottom 1990 Clipped 3.55 to 3.65m from left, 0.5 to 3.5m from bottom 1991 Clipped 0.6 to 0.7m from left, 0.5 to 3.5m from bottom 1992 Clipped 3.3 to 3.4m from left, 0.5 to 3.5m from bottom 1993 Clipped 3.65 to 3.75m from left, 0.5 to 3.5m from bottom 1994 Clipped 0.25 to 0.35m from left, 0.5 to 3.5m from bottom 1996 Clipped 3.4 to 3.5m from left, 0.5 to 3.5m from bottom 1997 Clipped 0.5 to 0.6m from left, 0.5 to 3.5m from bottom 1999 Clipped 3.15 to 3.25m from left, 0.5 to 3.5m from bottom 2000 Clipped 0.75 to 0.85m from left, 0.5 to 3.5m from bottom 2002 Clipped 2.55 to 2.65m from left, 0.5 to 3.5m from bottom 2004 Clipped 1.90 to 1.80 from right, 0.5 to 3.5m from bottom Sampling Discrepancies in E002 Field A Year Sampling Discrepancy 1982 Plot 19 missing 590 sample 1983 In order to avoid gopher mounds the following changes were made: Plot 17 clipped at 0.40-0.50m from left side, Plot 32 clipped at 0.80-0.90m from left side, Plot 34 clipped at 0.40-0.50m from left side, Plot 36 clipped at 0.40-0.50m from left side, Plot 40 clipped at 0.60-0.70m from left side, Plot 52 clipped at 0.60-0.70m from left side 1984 Plot 15 clipped at 2.50-2.60m from left side, Plot 27 clipped at 3.30-3.40m from left side, Plot 44 clipped at 2.90-3.00m from left side, Plot 52 clipped at 2.80-2.90m from left side 1985 none 1986 Plot 35 clipped at 3.05-3.15m from left side 1987 none 1988 none 1989 none 1990 none 1991 none 1992 none 1993 Plot 7 clipped at 3.05-3.15m from left side to avoid old gopher mound 1994 Plot 4 clipped at 0.55-0.65m from left side to avoid a gopher mound 1996 none 1997 none 1999 Plot 26 clipped 0.75-0.85m from left side, Plot 51 clipped 0.75-0.85cm from left side, Plot 52 clipped 0.75-0.85m from left side 2000 Plots 18, 26, 36, 45, 50, 51, 52 clipped 3.00-3.10m from left 2002 none 2004 Plot 5, 42 clipped at 1.60-1.50m from right

Location of aboveground vegetation sampling in plot (4x4m) for E002 Field B

Listing of location of aboveground vegetation sampling in E002 Field B Year Clipped Area 1982 Clipped 0.25 to 0.35m from left, 0.5 to 3.5m from bottom 1982 Clipped 3.65 to 3.75m from left, 0.5 to 3.5m from bottom 1983 Clipped 0.5 to 0.6m from left, 0.5 to 3.5m from bottom 1984 Clipped 3.4 to 3.5m from left, 0.5 to 3.5m from bottom 1985 Clipped 0.75 to 0.85m from left, 0.5 to 3.5m from bottom 1986 Clipped 3.15 to 3.25m from left, 0.5 to 3.5m from bottom 1987 Clipped 0.9 to 1m from left, 0.5 to 3.5m from bottom 1988 Clipped 3 to 3.1m from left, 0.5 to 3.5m from bottom 1989 Clipped 0.5 to 0.6m from left, 0.5 to 3.5m from bottom 1990 Clipped 3.55 to 3.65m from left, 0.5 to 3.5m from bottom 1991 Clipped 0.35 to 0.45m from left, 0.5 to 3.5m from bottom 1992 Clipped 3.3 to 3.4m from left, 0.5 to 3.5m from bottom 1993 Clipped 3.65 to 3.75m from left, 0.5 to 3.5m from bottom 1994 Clipped 0.25 to 0.35m from left, 0.5 to 3.5m from bottom 1996 Clipped 3.4 to 3.5m from left, 0.5 to 3.5m from bottom 1997 Clipped 0.5 to 0.6m from left, 0.5 to 3.5m from bottom 1999 Clipped 3.15 to 3.25m from left, 0.5 to 3.5m from bottom 2000 Clipped 0.75 to 0.85m from left, 0.5 to 3.5m from bottom 2002 Clipped 2.55 to 2.65m from left, 0.5 to 3.5m from bottom 2004 Clipped 1.90 to 1.80m from right, 0.5 to 3.5m from bottom Sampling Discrepancies in E002 Field B Year Sampling Discrepancy 1982 Plot 36 548 missing weight 1983 none 1984 Plot 26 clipped at 3.15-3.25m from left 1985 none 1986 none 1987 none 1988 none 1989 none 1990 none 1991 none 1992 none 1993 Plot 53 clipped at 3.55-3.65m from left side to avoid an old gopher mound 1994 Plot 53 clipped at 0.70-0.80m from left side to avoid gopher mound 1996 none 1997 none 1999 none 2000 Plots 2, 6 clipped 3.00-3.10m from left 2002 none 2004 none

Vegetation Sampling

Vegetation sampling is done the same way in each of the three fields. Plots in experiment E002 were sampled every year for twelve years and has since been sampled at least every other year. Each year, the sample strip is located in a different place. Documentation on where the strips were located for each year can be found in the sampling maps. A 10cm x 3m strip of vegetation is clipped out of each plot. Sampling is done in the same manner as, and in conjunction with, experiment E001. That is, after E001 is clipped in field A, E002 is clipped in field A, and so on, making field A harvest early July, field B in late July or early August, and field C in mid August. See above ground vegetation sampling for details on equipment and other field methods.

rbe002 - Root biomass data

Vegitation Sampling

Vegetation sampling is done the same way in each of the three fields. Plots in experiment E002 were sampled every year for twelve years and has since been sampled at least every other year. Each year, the sample strip is located in a different place. Documentation on where the strips were located for each year can be found in the sampling maps. A 10cm x 3m strip of vegetation is clipped out of each plot. Sampling is done in the same manner as, and in conjunction with, experiment E001. That is, after E001 is clipped in field A, E002 is clipped in field A, and so on, making field A harvest early July, field B in late July or early August, and field C in mid August. See above ground vegetation sampling for details on equipment and other field methods.