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.

ANT METADATA

INTRODUCTION

The long-term data for the ant community at the long-term site near Portal, Arizona, has been used to address a variety of questions including (1) the effects of ants on the annual plant community, (2) the effects of rodents on the ant community, (3) responses of ants to climatic variability, and (4) documenting competitive interactions between ant species.

This metadata file describes the field data collection techniques and data structure for the ant data set. Two different types of data on the ant community are taken at the study site: bait data and colony data. Collection of bait data started in 1988 and consists of the number of each species of ant observed at baits. Colony data consists of the total number of individual colonies and the number of colony openings for all diurnal species of ants and one nocturnal species, Myrmecocystus mexicanus, whose colonies are identified by their stone entrances. Colony data before 1988 are only available as totals for an entire plot. After 1988, colony data are available at the level of quadrats within plots. Because of the different kinds of data collected, the ant community data set consists of three datafiles. No data is available for any data type from 1995–1997 because changes in methodology resulted in severe data quality issues. Further details on the ant community and data collection are detailed in this file.

METADATA CLASS I. DATA SET DESCRIPTORS

A. Data set identity:

Title: Long-term monitoring and manipulation of an ant community in the Chihuahuan Desert near Portal, Arizona, USA.

B. Data set identification codes:

Portal_ant_colony_19771987.csv

Portal_ant_colony_19882002.csv

Portal_ant_bait_19882002.csv

C. Data set description

Principal Investigators:

Thomas J. Valone, Department of Biology, Saint Louis University, Saint Louis MO 63103

S. K. Morgan Ernest, Department of Biology, Utah State University, Logan UT 84322

James H. Brown, Department of Biology, University of New Mexico, Albuquerque NM 87131

Abstract: The data set covers a 25 year period (1977–2002) of detailed ant sampling of an arid ecosystem in near Portal, Arizona, USA. Each year ant colonies are counted within 49 circular 2-m radius quadrats on each of 24 experimental plots. In addition, a yearly bait census is conducted using 25 regularly spaced 10 cm diameter crushed bait piles on each plot. The data set should prove useful for studies of population dynamics and species interactions. Sampling is ongoing and data will be added over time.

D. Key words: ants, bait census, climate, colony counts, competition, granivory, LTREB data.

CLASS II. RESEARCH ORIGIN DESCRIPTORS

A. Overall project description

Identity: Bait and colony based data for the 24 experimental plots at the 20 ha study site in the Chihuahuan Desert near Portal, Arizona.

Originators: Drs. James H. Brown, Diane W. Davidson, and James Reichman

Period of Study: 1977–2002

Objectives: To monitor (a) the community- and population-level dynamics of desert ants and (b) the effects of granivore manipulation on this community.

Source(s) of funding: See metadata.htm

B. Specific subproject description

1. Site description: Within the 20 ha study area there are 24 experimental plots. Each plot has an area of 0.25 ha and is fenced to regulate rodent access to the plot. Rodent treatments include controls, kangaroo rat removal, and rodent removal. The ant community, which is also predominately granivorous, is also manipulated. Ant treatments include controls and ant removals. Through 1980, ants were removed through the use of Mirex [Allied Chemical Corporation], a commercial ant poison. After 1980, poisoning was conducted with AMDRO [American Cyanamide Company] (Davidson et al. 1985).

On each plot there are 49 permanent stations marked by rebar stakes forming a 7 × 7 grid. Rows are numbered 1–7 going from the most northern row to the most southern. Columns are numbered 1–7 going from the most western column to the most eastern. Every stake on a plot has a unique identifying number denoting the coordinate of that stake on that plot. For example, stake 11 is the first stake on the first row. (See metadata.htm, Fig 1).

Treatments: See metadata.htm, Table 1, for details on treatment assignments for each plot.

Data Collection Period, Frequency: Census of the ant community occurs every year over a two week period during July after the summer monsoons have begun.

3. Research Methods

Field: Bait census: Bait censuses began in 1988.  On each plot on one morning in July, we set 25 bait piles on each plot. Bait piles consist of crushed millet placed on the ground in a 10-cm diameter circle. Bait piles are placed at the base of the permanent rebar stakes. In rows 1, 3, 5, and 7 we place bait at all odd column stakes (e.g., stake 11, 13, 15, 17).  In rows 2, 4, and 6, we place bait piles at even numbered column stakes (e.g., stake 22, 24, 26).  This creates a checkerboard layout of bait piles across the entire plot. Baits are established at dawn and ants are allowed to recruit to bait piles for 1.5 hours. After 1.5 hours, all bait piles are censused recording all individuals of all species within the 10-cm diameter bait circle.

Colony census:  We record the number of colony entrances for all diurnal species within a 2-m radius circle that is centered 2-m north of each of the 49 permament stakes. For each colony entrance, we record the species identity and determine whether any additional entrances exist within 0.5 m. If so we define that as one colony with multiple entrances. There are two exceptions to this procedure. For Solenopsis, we simply record the presence or absence of any colony entrance within the 2-m radius circle. For Novomessor, we record the presence of all colony entrances within the 0.25-ha plot noting the nearest stake to the colony entrance. Before 1988, we only have plot totals (totals for all 49 stakes) for each species. Starting in1988, we have data for each stake.

Taxonomy and systematics: Bolton, B. 1995. A new general catalogue of the ants of the world. Harvard University Press.

4. Project personnel: Our current estimate of the number of people who have assisted with the ant census is currently over 75. Many of these people assisted on a volunteer basis and this work would not have been possible without their help.

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: Species have been sent to Dr. Michael Kaspari for independent verification. In the field, all identifications are double checked by Valone if there are any questions.

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 Thomas J. Valone on two separate machines. Original data sheets also reside with Thomas J. Valone.

Contact person: Thomas J. Valone, Department of Biology, Saint Louis University, Saint Louis MO 63103.  email: [email protected]

Copyright restrictions: None.

Proprietary restrictions: None. However, we do request that authors of publications using the ant database notify Thomas J. Valone (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

PRE-1988 ANT COLONY CENSUS

A. Data Set File:

Identity: Portal_ant_colony_19771987.csv

Size: 265 rows (including header), 36 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_ant_colony_19771987.csv
Each row contains information on the number of colonies (columns with headings: [speciescode]) and colony openings (denoted by column names: [speciescode]O) counted for each species on a plot (the exception to this is for SOLA and SOLB, for which only the presence of a colony was recorded, not the number colonies or openings). If two openings for a species were < 0.5 m apart they were considered to belong to the same colony. For Novomessor, we sample the entire 0.25-ha plot for colonies and record colony location to the nearest quadrat.

POST-1987 ANT COLONY CENSUS

A. Data Set File:

Identity: Portal_ ant_colony_19882002.csv

Size: 14113 rows, 1478 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_ant_colony_19892002.csv
Each row contains information on the number of colonies and colony openings counted for each species on a plot (the exception to this is for SOLA and SOLB, for which only the presence of a colony was recorded, not the number colonies or openings). If two openings for a species were < 0.5 m apart they were considered to belong to the same colony. For Novomessor, we sample the entire 0.25-ha plot for colonies and record colony location to the nearest quadrat.

ANT BAIT CENSUS

A. Data Set File:

Identity: Portal_ant_bait_19882002.csv

Size: 7201 rows (including header), 387 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 3. Column information for Portal_ant_bait_19882002.csv
Each row contains information on the number of individuals of each species censused on a particular quadrat during a particular year.

Table 4. Ant Species codes and scientific names.

CLASS V. SUPPLEMENTAL DESCRIPTORS

A. Publications using the data set: See overview metadata.htm

LITERATURE CITED

Davidson, D. W., D. A. Samson, and R. S. Inouye. 1985. Granivory in the Chihuahuan Desert: Interactions within and between trophic levels. Ecology 66:486–502.