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Methods for Experiment 011 -

Field Operations: Burning

Starting in the spring of 1992, half of all plots in E011 in fields A and B were burned. These plots will be burned each spring.

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. For a list of fertilizer treatments for each plot, see file trmte11. Starting in the spring of 1992, half of all replicates of each treatment in fields A and B were assigned to receive no more fertilizer. For a list of treatments stating whether each plot receives its usual fertilizer treatment or no fertilizer, see file trmte100. On May 5, 1995 a wildfire burned all of the plots in experiment11 in field B.

Light Penetration

Light meter readings for E011 were taken in 1984, 1985 and 1990 in the same way as in E001 except gopher mounds were ignored. Light meter readings were taken in the same positions in all plots, regardless of the presence of gopher mounds.

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

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:

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.

Sampling Map for A011

Sampling map for A011 is not currently available. Clip strips are 10cm wide and 3m long. 1984: Clipped 50cm from right side 1985: Clipped 50cm from left side 1990: Clipped 65-75cm from right side 1992: Clipped 90-100cm from left side Sampling Problems in A011: 1984: none 1985: none 1990: none 1992: none

Sampling Map for B011

Sampling map for B011 is not currently available. Clip strips are 10cm wide and 3m long except in 1990 when they were 10cm wide and 1m long. 1984: Clipped 50cm from right side 1990: Clipped 60-70cm from TAG in SW corner, oriented in N-S direction. 1991: Clipped 35-45cm from left side 1992: Clipped 45-55cm from right side if there was no light shad in the plot or if the light shade is on the left side of the plot. Clipped 45-55cm from left side if the light shade is on the right side of the plot. Sampling Problems in B011: 1984: none 1990: sample size was 10cm x 1m 1991: none 1992: none Other Notes: Experiment E036 was set up on half of the plots of E011 in field B in 1987. Those plots without light shades are still considered B011 plots.

Sampling Map for C011

Sampling map for C011 is not currently available. Clip strips are 10cm wide and 3m long. 1984: Clipped 50cm from right side 1990: Clipped 65-75cm from right side Sampling Problems in C011: 1984: C-11-1 clipped at 75cm from right side C-11-8 clipped at 75cm from right side C-11-10 clipped at 85cm from right side C-11-16 clipped at 70cm from right side 1990: none Other Notes: In 1990, the plots in C011 that were clipped were only those plots NOT used in Experiment C053 which was superimposed on experiment C011.

Treatment layout : trmte11

Vegetation Sampling Methods

E011 is in fields A, B and C. Vegetation sampling is done the same way in each of the three fields. The plots in this experiment are not sampled on a regular 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 sampling maps. Sample size was 0.1m x 3m.