S. K. Morgan Ernest, Thomas J. Valone, and James H. Brown. 2009. Long-term monitoring and experimental manipulation of a Chihuahuan Desert ecosystem near Portal, Arizona, USA. Ecology 90:1708.
INTRODUCTION
The long-term data on precipitation at the long-term site near Portal, Arizona, has been used to study the relationship between precipitation and community dynamics (e.g., abundance changes in plants, ants, rodents, or overall ecosystem structure) and relationships between extreme precipitation events and species declines. This metadata file describes the field data collection and data structure for the precipitation data set. Because the spatial scale of the study site is relatively small relative to the scale at which precipitation events occur, there is only one precipitation measurement for the site. The location of the precipitation gauge can be found on the map of the site ( metadata.htm; Fig 1). There are two precipitation data files (1980–1989 and 1989–2002). The separate files reflect changes in the time scale at which precipitation data was collected (approximately daily-to-weekly vs. hourly, respectively). Further details on data collection are detailed in this file.
METADATA CLASS I. DATA SET DESCRIPTORS
A. Data set identity:
B. Data set identification codes:
Portal_precipitation_19801989.csv Portal_precipitation_19892002.csv
C. Data set description
Principal Investigators:
S. K. Morgan Ernest, Department of Biology, Utah State University, Logan UT 84322
Thomas J. Valone, Department of Biology, Saint Louis University, Saint Louis MO
James H. Brown, Department of Biology, University of New Mexico, Albuquerque NM 87131
Abstract: The data set covers a 23 year period (1980–2002) of precipitation monitoring near Portal, Arizona. From 1980–1989, monthly precipitation values collected at the site are available. In 1989, the site switched to an automated weather station which recorded hourly rainfall amounts.
D. Key words: precipitation, Chihuahuan Desert, LTREB data.
CLASS II. RESEARCH ORIGIN DESCRIPTORS
A. Overall project description
Identity: Long-term monitoring of precipitation near Portal, Arizona,USA.
Originators: Drs. James H. Brown, Diane W. Davidson, James Reichman
Period of Study: 1980–2002
Objectives: To monitor availability of a limiting resource (i.e., water) and its effects on the dynamics of a desert ecosystem.
Source(s) of funding: See metadata.htm
B. Specific subproject description
1. Site description: The 24 experimental plots cover an area not more than 20 ha in size. Due to the small spatial-scale of the plot and the spatial scale of the typical precipitation event, there is only one weather station for the site. This station has been located in the same general vicinity of the 20 ha site since 1980 (See metadata.htm, Fig 1 for location).
Data Collection Period, Frequency: Before 1989, precipitation was collected in a standard “manual” rain gauge and approximately weekly a volunteer residing in the vicinity would visit the site and collect data on rainfall amounts. There is no existing documentation for data collected before 1989. From the data, it appears that this individual may have tried to visit the site whenever there was precipitation in the area. Because dates associated with precipitation values have little accuracy or meaning, we have provided only monthly precipitation values from 1980–1989. In 1989, an automated weather station was installed at the site (Campbell Scientific) capable of recording precipitation amounts on an hourly basis. The automated and manual collection protocols were run concurrently for approximately 2 months until the old weather station was hit by lightning. No information currently exists on the make or model of the rain gauge for the first automated weather station. After a serious malfunction in February 2002, a new automated weather station (Campbell Scientific) was installed in December 2002. The rain gauge associated with the current weather station is a Texas Electronics 8 inch gauge (TE525WS-L). The precipitation data are divided into two files (1980–1989 and 1989–2002) to reflect the different frequencies of data collection.
3. Research Methods
Field: 1980–1989: Very little documentation exists regarding collection of precipitation data prior to 1989.
1989–2002: Data are downloaded monthly in conjunction with the monthly rodent census. While we do not appear to have documentation on the accuracy of the rain gauge associated with the first automated weather station, we do know that it was a tipping bucket rain gauge and the data suggest that each tip was equal to 0.254 mm. This is equivalent to the tipping bucket rain gauge associated with the current weather station which began operation in 2002.
CLASS III. DATA SET STATUS AND ACCESSIBILITY
A. Status
Latest Update: October 2007
Latest Archive date: October 2007
Metadata status: The metadata are complete and up to date.
Data verification: A manual rain gauge is maintained on site and periodically checked to provide independent verification of rainfall amounts.
B. Accessibility
Storage location and medium: (Ecological Society of America data archives [Ecological Archives], URL published in each issue of its journals). Original data files reside with S. K. Morgan Ernest on two separate machines.
Contact person: S. K. Morgan Ernest, Department of Biology, Utah State University Logan UT 84322. E-mail: [email protected]
Copyright restrictions: None.
Proprietary restrictions: None. However, we do request that authors of publications using the precipitation database notify S. K. Morgan Ernest (contact information above) of publication of their study. This helps us by allowing us to make accurate reports to the National Science Foundation and document that the scientific community finds the data from this study to be useful.
Costs: None.
CLASS IV. DATA STRUCTURAL DESCRIPTORS
1980–1989 PRECIPITATION DATA
A. Data Set File:
Identity: Portal_precipitation_19801989.csv
Size: 3493 rows (including header), 47 kilobytes.
Format and storage mode: ASCII text, comma delimited. No compression scheme used.
Header information: The first row of the file contains the variable names below.
Alphanumeric attributes: Mixed
B. Variable information
Table 1. Column information for Portal_precipitation_19801989.csv
Variable name |
Variable definition |
Storage type |
Variable codes, definitions, and notes |
Year |
Year data collected |
Integer |
1980–1989 |
Month |
Month data collected |
Integer |
1–12 |
Precipitation |
Precipitation amount in rain guage |
Double |
Measurement unit: millimeters -99 = missing data |
1989–2002 PRECIPITATION DATA
A. Data Set File:
Identity: Portal_ precipitation_19892002.csv
Size: 106457 rows (including header row), 2138 kilobytes.
Format and storage mode: ASCII text, comma delimited. No compression scheme used.
Header information: The first row of the file contains the variable names below.
Alphanumeric attributes: Mixed.
B. Variable information
Table 2. Column information for Portal_precipitation_19892002.csv
NOTE: gaps in data collection exist due to malfunctions of the weather station.
Variable name |
Variable definition |
Storage type |
Variable codes, definitions, and notes |
Year |
Year data collected |
Integer |
1989–2002 |
Month |
Month data collected |
Integer |
1–12 |
Day |
day data collected |
Integer |
1–31 |
Hour |
Hour data collected |
Integer |
1–24 |
Precipitation |
Precipitation amount |
Double |
Measurement unit: millimeters |
CLASS V. SUPPLEMENTAL DESCRIPTORS
A. Publications using the data set: See overview metadata.htm