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Methods for Experiment 025 -

Animal Sampling Methods

Small mammal trapping in E025 is the same as that in E001.

Field Operations: Fencing

The plots in experiment E025 are enclosed by a fence to exclude mammalian herbivores. 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.

Field Operations: Fertilization

Plots are fertilized at one of the following sets of times:

1. 1st & 3rd weeks of May
2. 1st & 3rd weeks of June
3. 1st & 3rd weeks of July

Each plot gets the fertilizer mixture specified by its fertilizer treatment code.

Field Operations: Mammal Trapping

Small mammals are trapped as often as possible to keep the resident population low. A list of the number and kind of mammals taken from each field is in the small mammal documentation file. Pocket gophers are trapped out of the fields as soon as they appear. Gopher mounds are then removed and vegetation is unburied. On May 5, 1995, a wildfire burned all of the plots in experiment 25 in field B.

Light Penetration

Light meter readings for E025 were taken in the same way as in E001.

Light Penetration Measurements Methods

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 ).

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 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

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:

Rate Volume Element
10 g/m2 150 ml P2O5 (0-46-0)
10 g/m2 150 ml K2O (0-0-61)
20 g/m2 200 ml CaCO3 (lime)
15m2 200 ml MgSO4 (Epsom Salts)
0.0625 ml/m2 trace mineral solution in 1 ml to 10 ml sand
 

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:

Treatment Rate Volume
A 0.0 g/m2 0 ml
B 1.5 g/m2 25 ml
C 3.0 g/m2 50 ml
D 5.0 g/m2 90 ml
E 8.0 g/m2 140 ml
F 14.0 g/m2 250 ml
G 25.0 g/m2 445 ml
H 40.0 g/m2 710 ml
I 0.0 g/m2 0 ml
 

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:

Experiment Treatments Plot size (m2)
Experiment 1 except Field D A thru I 16
Experiment 1 Field D A thru I 6
Experiment 2 A thru I 16
Experiment 4 E, G, I 1000
Experiment 8 C, F, H, I 16
Experiment 9 C, F, H, I 16
Experiment 11 E, G, I 16
Experiment 24 E, G, I 16
Experiment 25 E, G, I 5.25
Experiment 52 A, C, F, G 25
 

Sampling Map for A025

Sampling map A for e025 is not currently available.

Clip strips are 10cm wide and 2m long.

1985: Clipped 10-20cm from left side
1986: Clipped 10-20cm from right side
1987: Clipped 25-35cm from left side

Sampling Problems A025:

1985: none
1986: none
1987: none

Sampling Map for B025

Sampling map B for e025 is not currently available.

Clip strips are 10cm wide and 2m long.

1985: Clipped 10-20cm from left side
1986: Clipped 10-20cm from right side
1987: Clipped 25-35cm from left side
1988: Clipped 25-35cm from right side

Sampling Problems B025:

1985: none
1986: none
1987: none
1988: none

Treatment layout : trmte25

Field Identification Experiment Number Plot Number Time of Nitrogen Application Nitrogen Treatment Ammonium Nitrate(34-0-0) addition(g /m2/yr)
A2513750
A2523516
A253090
A2543750
A2551516
 

Vegetation Sampling Methods

E025 is in fields A and B. Plots in this experiment are sampled on an approximately annual basis. Each time it is sampled, the sample strip is located in a different place.

Documentation on where the strips are located for each year can be found in the clipping maps.

Sample size is 10 cm x 2 m.