Study Number: 

1013

Project Title:

Terrestrial gradient microclimate measurements.

Investigator(s):

Lloyd Swift (Retired)  E-Mail
Affiliated Institution(s): University of Georgia  (Argo, Kloeppel, Steiner, Taylor, Zausen)
USDA Forest Service  (Swift)
Address: Coweeta Hydrologic Laboratory
3160 Coweeta Lab Road
Otto, North Carolina 28763 USA
Study Type: Terrestrial
Project Type: Coweeta Core Research
Study Period:

08/1991 - Present
Status/Notes:

Type 1
Funding Source(s):

National Science Foundation, DEB-9632854 (Text Version) and DEB-0218001 (Text Version) to Coweeta LTER.
Abstract: The terrestrial gradient study at Coweeta compares vegetation, soils, and understory microclimate of five sites: 118 low elevation (782 m) pine-oak, 218 low elevation (795 m) cove hardwood, 318 low elevation (865 m) mixed oak, 427 high elevation (1001 m) mixed oak, 527 high elevation (1347 m) northern hardwood. Understory microclimate stations were installed in representative locations at the downslope margin of each 20 x 40 m gradient plot (within the 80 x 80 m plot).


Resources for students about terms used in this study:
Forest layers - Source: Boise National Forest, US Forest Service
Microclimate - Source: United Kingdom's Met Office
Air temperature patterns - Source: University of Wisconsin - Stevens Point
Soil Water Content - Source: University of Sydney
Location(s), Described: Watershed 18 and Watershed 27.

See Project Summary Sheet 1048 and Terrestrial Gradient Sites: Characteristics (photographs) for detailed information about plot locations and physical descriptions, respectively.

X and Y tape-measurement coordinates submitted by Paige Carithers on 14 May 2001.
Location(s), Download GPS: ArcView Shape Files (shp.):   UTM, NAD83, Zone 17  |  Lat/Lon 
Location(s), Online Map(s): USGS Topographic-based Maps of Research Sites
(Printable for fieldwork)
Methods/Experimental Design: All variables are collected with a Campbell Scientific, Inc. automated data logger - Model CR10. Air temperature and relative humidity sensors (Campbell Model 207) are exposed approximately 1.3 m above the forest floor. Soil temperature sensors are buried at 5 cm, 20 cm, and 50 cm below the soil-leaf litter interface by inserting sensor into the undisturbed sidewall of a small pit. Soil temperatures were originally collected with Model 107 thermistor sensors, later replaced with thermocouples constructed from 18 gage copper-constantan wire.  Soil temperature sensors at 50 cm were added October, 2000.  Water content measurements at the Top (0-30 cm and 30-60 cm) and Bottom (0-30 cm and 30-60 cm) commenced March 1999.  Stored data are copied from the logger approximately every 14-30 days.

After 2001, relative humidity, air temperature, and soil temperature manual observations were discontinued.

Pre 2001 Quality Assurance/Quality Control Procedures:
Prior to 2001 the following QAQC procedures were used for air temperature and soil temperature:
Air Temperature:
Minimum and maximum air temperatures recorded by the datalogger over a 2-4 week period are compared to a maximum/minimum thermometer installed below the sensor. If discrepancies of >2 degrees C occur, the thermometer is replaced. Following this, if the discrepancy continues, the sensor is replaced.

Soil Temperature:
Soil temperatures recorded using thermocouples wired to a datalogger are compared to readings taken using a REOTEMP soil thermometer. Because these measurements cannot be taken in exactly the same location, identical temperatures are not expected. If the thermometer readings are consistently higher or lower at one location than the thermocouple measurement, the thermocouple is replaced.

Current Quality Assurance and Quality Control:
This document provides quality assurance and quality control procedures for data collected for this project during 2008. If hourly data were missing or innaccurate due to low battery levels or sensor malfunction, the data for that hour are noted with a period ".". If one value was missing from one of the variables in the hourly data, the subsequent daily and monthly data sets were also denoted with a "." (e.g., if Julian day 45 had missing airtemp data from hour 500, then that whole day was coded as a ".", as well as the entire month for that day). This was the way earlier data were archived. If researchers want to conduct their own assessment of daily and monthly means, then they should probably use the hourly data as a starting place.

Water Content:
Volumetric water content at the Top 0-30 cm and 30-60 cm and Bottom 0-30 cm and 30-60 cm commenced March 1999. These measurements are collected with the CS615 Water Content Reflectometer from Campbell Scientific, Inc. The sensors are installed at two locations (at the top of the original 20 by 40 m plot and at the bottom of the original 20 by 40 m plot) at two depths (0 to 30 cm and 30 to 60 cm). See attached table and maps for grid locations. On October 4, 2006 all CS615 sensors were upgraded to CS616 sensors for sites 118, 218, and 318. And on October 5, 2006 sensors were upgraded at sites 427 and 527. Prior to these automated readings, soil moisture was measured with a Tektronix 1502B Time Domain Reflectomer (TDR). For 23 months beginning 21 April 1997, a CS615 reflectometer was installed horizontally near the TDR rods at site 427 with probes at depths of 5 and 20 cm. Readings were taken to compare the CS615 with the Tektronix.

Please see Metadata #1023 for onsite comparison of TDR readings to CR10 readings (using the Campbell Scientific Model CS615 Water Content Reflectometer) for gradient site 427 from April 1997 through March 1998.

Please also reference Metadata #1023 for a laboratory comparison of TDR vs. reflectometer readings.

See attached table and maps for grid locations.

 Comments:
On 27 August 1996 at 118 and on 18 September 1996 at all other sites, model 10TCRT Thermocouple Reference junction sensors were installed on CR10 dataloggers. Before that date, daily means of thermocouple observations are judged to be valid but the daily range of hourly values was exaggerated because the logger internal temperature was used for the reference junction value. The hourly departures of the thermistor observations from the daily mean were used to generate the hourly thermocouple values around its daily mean for the period up to the switch-over to the terminal board reference temperature.

On 11 February 1998, relative humidity and vapor pressure observations were terminated rather than investing in new sensors.

 Data Accuracy:
Sensor and datalogger manufacturer states that both air and soil temperature measurements with thermistors have overall accuracy typically better than +/- 0.2 C and relative humidity observation accuracy is better than +/- 5 percent. Campbell states that the sum of various cumulative errors of thermocouple measurements can be between +/- 0.5 to 1.0 C. The variability due to sensor placement and exposure is greater than these errors of measurement. Degradation of the relative humidity and thermistor soil temperature sensor is the greatest source of error.
Sampling Frequency: Hourly means are calculated from 15 minute observations until 30 October 1997. Thereafter, hourly means are calculated from one minute observations.
Data Columns: Daily values are the means of the hourly values.  Monthly values are the means of the daily values.

Hourly:
Site - Site number, see Terrestrial Gradient Plots Physical Descriptions
Year - Year sample taken
Julian date - Julian day
Time - Hour sample taken
Air T - Air temperature at 1.3 meters
Humidity - Humidity
Soil T 5 - Soil temperature at a depth of 5 cm
Soil T 20 - Soil temperature at a depth of 20 cm
Soil T 50 - Soil temperature at a depth of 50 cm
Ref Temp - Reference temperature
WC Top 0-30cm - Percent water content, top 0 – 30 cm
WC Top 30-60cm - Percent water content, top 30 – 60 cm
WC Btm 0-30cm - Percent water content, bottom 0 – 30 cm
WC Btm 30-60cm - Percent water content, bottom 30 – 60 cm

Daily:
site - Site number, see Terrestrial Gradient Plots Physical Descriptions
year - Year sample taken
month - Month sample taken
julday - Julian day
mairtemp - Air temperature at 1.3 meters
mhumid - Humidity
msoilt05 - Soil temperature at a depth of 5 cm
msoilt20 - Soil temperature at a depth of 20 cm
msoilt50 - Soil temperature at a depth of 50 cm
mreftemp - Reference temperature
mwctop30 - Percent water content, top 0 – 30 cm
mwctop60 - Percent water content, top 30 – 60 cm
mwcbot30 - Percent water content, bottom 0 – 30 cm
mwcbot60 - Percent water content, bottom 30 – 60 cm

Monthly:
site - Site number, see Terrestrial Gradient Plots Physical Descriptions
year - Year sample taken
month - Month sample taken
mairtemp - Air temperature at 1.3 meters
mhumid - Humidity
 msoilt05 - Soil temperature at a depth of 5 cm
msoilt20 - Soil temperature at a depth of 20 cm
msoilt50 - Soil temperature at a depth of 50 cm
mreftemp - Reference temperature
mwctop30 - Percent water content, top 0 – 30 cm
mwctop60 - Percent water content, top 30 – 60 cm
mwcbot30 - Percent water content, bottom 0 – 30 cm
mwcbot60 - Percent water content, bottom 30 – 60 cm

Missing Data Codes: . (Period)
Publications:

None.
Data Restrictions: Users must adhere to the Coweeta LTER Data Policy.
Metadata: EML Format (XML Schema) | Information about EML
Data Downloads: Monthly Data:
1991 - 2008:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

Daily Data:
 1991 - 1995:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 1996 - 2000:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 2001 - 2005:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

2006 - 2008:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

Hourly Data:
 1991:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 1992:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 1993:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

1994:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 1995:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 1996:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 1997:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 1998:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 1999:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)
2000:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

2001:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

2002:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

2003:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 2004:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

 2005:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

2006:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

2007:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)

2008:  Microsoft® Excel (.xls) | Text Comma Delimited (.csv) | DBase (.dbf)


IM PROCESS 1002:  ARCHIVING Project 1013