Rainfall Manipulation
Plot Data Manual
Soil Temperature
History:
Soil
Temperature was collected in the middle block plots (6,7,8,9,10)
at 5 and 15 cm depths during the growing season from 1998 through 2003. From 2003 to present, soil temperature has
been collected at 2 cm, 5 cm, and 15cm depths year round in each subplot in
plots 2, 3, 7, 8, 9, 11, and 12. Each
subplot contained two 2cm thermocouples, three 5cm thermocouples, and one 15 cm
thermocouple. Accessory grazing
experiment in the minirhizotron subplot removed grass
canopy cover and altered soil temperature in 2008-present. Probes possibly affected by her project were
removed from the dataset before the summary was created.
Collection:
The
type-T Thermocouples are multiplexed through an AM25T and read by a CR10x data
logger located in the block nema4 which measures the temperature (0C) every 30
seconds and records an average every 30 minutes. Daily automated data collection.
Processing:
After
automated data collection, soil temperature data is pulled from each blocks
logger file and merged together to create a soil temperature dataset with
treatment labels for all plots.
Column
Explanation/format:
soiltemp_summary98_**.sds
Date: ddMMMyy
Ramp: Plot (1-15)
Subplot: Subplot (1-4) N/A prior to 2003
Depth: Depth of probe (cm)
Subtrt: Heat
Treatment (warm/ctrl)
Trt: Precipitation
Treatment (98-02 ambi/vari/both/drgt/ctrl)(03-present ambi/vari/ctrl)
MaxTemp: Highest
½ hour average (0C)
MinTemp: Lowers
½ hour average (0C)
MeanTemp: Average
Temperature (0C)
Day_temp: Average
Temp noon-4pm (0C)
Night_temp: Average Temp midnight-4am (0C)
Year: Year (YYYY)
Drgt: Drought
Treatment indication (0=no, 1=yes) only valid 98-02
Vari: Variable
Rainfall indication (0=no, 1=yes)
Temp: Heated sub-treatment indication (0=no, 1=yes)
Block: Block design assignment (s=south,
m=middle, n=north)
Jday Julian
day (yyyyddd)
TDR Soil Moisture
History:
Soil
moisture data were collected on a weekly basis during the growing season
starting in 1998. Measurements were taken using TDR probes and a portable cable
tester. Sixteen measurements were taken in each plot for each depth (0-15cm and
0-30cm) until 2001 when the number of measurements per plot was decreased to four
at each depth (one measurement per subplot). In 2002 only 0-30cm data were
collected. The TDR system was replaced in 2005 with an automated system which
collected data from one Campbell Scientific CS616 probe per subplot at the
0-15cm depth throughout the year. In
June 2006, two 0-30cm probes per plot were added to the system. In 2008, two additional 0-30cm cs616 probes
were added per plot to the remaining subplots.
Collection:
The
TDR probes were measured with a portable cable tester which was carried to each
plot by a technician. The technician connected the cable tester to each probes
cable and recorded a valid reading. In the automated system, each CS616 probe
in a block is multiplexed through an AM16/32 and read by a CR10X. Beginning in
2005, a measurement was taken every 60 seconds, and an average of these values
was recorded every 30 minutes. In July 2006, though the 30 minute output
interval remained unchanged, the number of measurements taken was decreased to
one every 120 seconds. Data are automatically collected from the logger on a
daily basis.
Processing:
After
TDR data were collected in the field, they were hand-entered into a computer,
and site-specific calibrations were applied using SAS to calculate volumetric
water content (VWC). After CS616 data
is automatically downloaded, it is processed using SAS which combines data from
each block and calculates VWC using the site-specific quadratic equation. TDR data were processed as follows:
*
Removed impossible values (VWC<0.05 or VWC>1)
*
Performed regressions to predict missing 0-15cm data from 0-30cm data and vise versa.
*
Filled gaps of missing data at one depth using the value from the other depth
and the regression equation
CS616
data are processed as follows:
*
Remove data from time periods when a probe may be malfunctioning. These data
are found by finding the average difference between the two probes of the same
sub-treatment and depth in each plot. If the difference at any one point is
farther than one standard deviation from the mean difference, then the probe of
that sub-treatment and depth with the value that is farthest from the mean VWC
for the plot at that depth is removed.
*
Data are graphed and checked visually for:
o Long time periods when a probe is obviously
malfunctioning (lagged response to rain events, exaggerated swings from very
wet to very dry)
o Time periods when both probes of the same
sub-treatment and depth are malfunctioning
o Blow-in events where parts of a plot got
rain and others did not (these remain in the dataset)
*
Perform regressions to predict missing values using data from the other probe
of the same sub-treatment and depth in a plot (blow-in events are not used in
the regressions)
*
Fill gaps with predicted values
Following
these steps, TDR and CS616 data are combined and high VWC values are capped at
.60. Then two datasets are created. One with CS616 data at a 30 minute interval
and another with a daily mean VWC. These datasets are named
soilmoisture98**_30min.sds and soilmoisture98**_daily.sds
(where ** represents the most recent year) respectively. Both datasets include
gap-filled and unfilled data.
Column
Explanation/format: soilmoisture98**_daily.sds
Date: ddMMMyy
Ramp: Plot (1-15)
Subplot: Suplot
(1-4) N/A prior to 2003
Depth_cm: Probe
Depth (15cm or 30cm)
VWC: Volumetric Water Content (%)
VWC_filled: Volumetric Water Content Gap filled data
(%)
Sample: Sample # within plot (only relevant
98-02)
Year: Year (YYYY)
Trt: Precipitation
Treatment (98-02 ambi/vari/both/drgt/ctrl)(03-present ambi/vari/ctrl)
Drgt: Drought
Treatment indication (0=no, 1=yes) only valid 98-02
Vari: Variable
Rainfall indication (0=no, 1=yes)
Temp: Heated sub-treatment indication (0=no, 1=yes)
Block: Block design assignment (s=south,
m=middle, n=north)
Subtrt: Heat
Treatment (warm/ctrl)
Jday Julian
day (ddd)
Canopy Temperature
History:
In
April of 2004, two Apogee infrared canopy temperature sensors were installed in
plots 2, 3, 11, and 12, one per sub-treatment.
Sensors were removed prior to each spring burning and replaced shortly
following. In July 2010 Sensors were
removed and used for the Climate Extremes Experiment. Ants at various times built nests in the
junction boxes which altered the sensor signal requiring removal of blocks of
data.
Collection:
Sensors
were read every 30 seconds by a CR10x datalogger.
Processing:
SAS
run to filter the data by:
*
Removing out of range values (<-400C or >600C)
*
Generates correlation coefficients between sensors of like treatment
*
Removes probes with <.8 correlation to sensors with the same treatment
*
Creates sub-treatment means
*
Adds additional treatment variables and labels
Column
Explanation/format: camopytemp98**.sds
Subtrt: Heat
Treatment (warm/ctrl)
Date: ddMMMyy
Time: hh:mm
Jday Julian
day (ddd)
Year: Year (YYYY)
Ramp: Plot (1-15)
Trt: Precipitation
Treatment (98-02 ambi/vari/both/drgt/ctrl)(03-present ambi/vari/ctrl)
Drgt: Drought
Treatment indication (0=no, 1=yes) only valid 98-02
Vari: Variable
Rainfall indication (0=no, 1=yes)
Temp: Heated sub-treatment indication (0=no, 1=yes)
Block: Block design assignment (s=south,
m=middle, n=north)
TempC: Temperature
of canopy in viewing area (0C)
Neutron Probe Soil
Moisture
History:
Deep
soil moisture has been monitored at RaMPS every 2-4
weeks with a Troxler 4300 neutron probe since
2001. A technician lowers the probe into
three aluminum access tubes per plot to 25, 50, 75, 100, 125, and 150 cm depths
(deeper depths omitted if bed rock present) and allows the probe to calculate
volumetric water content using the factory provided calibration. Since heating began in 2003, tubes 1 and 3 are in heated subplots, 2 is not. The value is recorded in kg H2O/m3. Originally, the reading was allowed to
average over a 60 second period. This
was lowered to 15 seconds in late 2010 after comparative tests. A calibration attempt was made in 2007 by
comparing probe readings and oven dried soil samples collected using a geoprobe soil corer at a site below plot 6. Depth specific calibration equations were
created but due to topography and low correlation dont eliminate much
variability in the data. Due to soil
variability and the inability to create tube specific calibrations, caution
should be used in the use of this data.
A summary dataset expressing VWC as an index value is also created.
Collection:
Manual
collection from hand held probe. Values
recorded on data sheets and hand entered into an excel spreadsheet.
Processing:
SAS
program run which indexes to the wettest value for each hole each day, creates
an average, and reformats variables to the standard naming format. This dataset is useful for comparing water
distribution within the soil column at a given date but does not allow for
direct comparisons across dates.
Column
Explanation/format: NP_index_01**.sds
Date: ddMMMyy
Ramp: Plot (1-15)
Trt: Precipitation
Treatment (98-02 ambi/vari/both/drgt/ctrl)(03-present ambi/vari/ctrl)
Jday Julian
day (ddd)
Year: Year (YYYY)
Drgt: Drought
Treatment indication (0=no, 1=yes) only valid 98-02
Vari: Variable
Rainfall indication (0=no, 1=yes)
Depth: Depth of probe (cm)
Hole 1: VWC
in hole 1 at that depth/Max VWC for hole 1 on that day
Hole 2: VWC
in hole 2 at that depth/Max VWC for hole 2 on that day
Hole 3: VWC
in hole 3 at that depth/Max VWC for hole 3 on that day
Average: Average of the index values at the 3
locations within the plot at that depth
Ceptometer
History:
Light penetration though the plant canopy has
been measured since 2003 with a Decagon AccuPAR
quantum sensor which measures photosynthetically
active radiation over the length of an 84cm long rod. Readings were used to determine heater
height: 120 cm above 60% light loss.
Collection:
Readings
are taken every 10 cm from the ground to the top of the canopy mid day at 2-3
week intervals during the growing season.
Two measurement sets are taken in the southeast (sunny) half of each
subplot and one on the northwest (partially shaded by heater) half of the
plot. Values are recorded on a data
sheet in the field and entered by hand into an excel spreadsheet.
Processing:
After
excel entry, SAS program is run to add treatment labels, average values and
determine percent PAR transmittance and percent PAR reduction.
Column
Explanation/format: ceptometer03**.sds
Ramp: Plot (1-15)
Trt: Precipitation
Treatment (ambi/vari/ctrl)
Subplot: Suplot
(1-4) N/A prior to 2003
Subtrt: Heat
Treatment (warm/ctrl)
Height: distance above ground (cm)
Par1: mmol
m-2s-1
Par2: mmol
m-2s-1
Par3: mmol
m-2s-1
Date: ddMMMyy
Subplotpct: averaged % PAR reduction
Pcttrans: averaged
% PAR transmittance
Temp: Heated sub-treatment indication (0=no, 1=yes)
Vari: Variable
Rainfall indication (0=no, 1=yes)
Soil CO2
History:
Soil
CO2 flux has been monitored at RaMPs since 1998. A Li 6200 collected data from 1998 until the
fall of 2007. From the spring of 2008 to
present, two Li 8100s with 10 cm chambers were used. A cross calibration between the two systems
in 2008 showed no significant difference in flux values, although variability
was greatly reduced with the Li 8100.
Between 1998 and 2002, 5 measurements were taken per plot. When the heat treatment was added in 2003, 2
measurements per subplot, on separate collars, were taken. The height of the soil collars used for the
8100 is measured several times a season to increase the accuracy of the
reading.
Collection:
A
technician places the chamber onto the seasonally placed PVC collar, inputs the
location, and runs the IRGA program which stores the flux values over a 45
second period and calculates a flux value.
After collection, the 8100 is connected to a PC and the data is
downloaded to the network.
Processing:
Licor File Viewer exports the data to a
text file where the two machines files are merged.
Data
is pulled into SAS, the correct soil collar height added to each specific
location and flux recalculated with the corrected chamber volume.
Column
Explanation/format: soilflux98**.sds
Date: ddMMMyy
Ramp: Plot (1-15)
Meas: Measurement
# (1-5) valid 98-02
Page: Location of raw data file
Year: Year (YYYY)
Trt: Precipitation
Treatment (98-02 ambi/vari/both/drgt/ctrl)(03-present ambi/vari/ctrl)
Drgt: Drought
Treatment indication (0=no, 1=yes) only valid 98-02
Vari: Variable
Rainfall indication (0=no, 1=yes)
Block: Block design assignment (s=south,
m=middle, n=north)
Photo: Flux value (mmol
m-2 sec-1)
Day: day of month (dd)
Month: Month (mm)
Subplot: Suplot
(1-4) N/A prior to 2003
Temp: Heated sub-treatment indication (0=no, 1=yes)
Subtrt: Heat
Treatment (warm/ctrl)