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 plant community at the long-term site near Portal, Arizona, has been surveyed since 1977. Surveys provide information on the abundance of both annual and perennial plants occurring on permanently marked quadrats. Because of the bimodal precipitation pattern, there are two – mostly distinct – annual plant communities at the Portal Project study area consisting of a winter and a summer set of species. The long-term data for the plant communities at the long-term site near Portal, Arizona, have been used to address a variety of questions including (1) the effects of the granivore guild on plant community structure, (2) responses of plants to climatic variability, (3) the relationship between the diversity of a quadrat and the stability of community and population dynamics. This metadata file describes the field data collection techniques and data structure for the plant datasets. The plant community dataset consists of eight files, reflecting important differences between the types of data they contain. First, all data is separated by season (winter or summer), reflecting important differences between these seasons. In particular, summer and winter annual communities consist of the mostly non-overlapping species compositions, requiring these communities to be considered separately for most questions. Second, before 1989 data collection focused primarily on more common species. Therefore, we have separated pre and post 1989 data to reflect that these are not comparable at the community-level. Finally, data for annual and perennial plants are separated.

METADATA CLASS I. DATA SET DESCRIPTORS

A. Data set identity:

Title: Long-term monitoring and manipulation of summer and winter desert annual and herbaceous perennial plant communities in the Chihuahuan Desert near Portal, Arizona, USA.

B. Data set identification codes:

Portal_plant_summer_annual_19831988.csv

Portal_plant_summer_perennial_19831988.csv

Portal_plant_summer_annual_19892002.csv

Portal_plant_summer_perennial_19892002.csv

Portal_plant_winter_annual_19831988.csv

Portal_plant_winter_perennial_19831988.csv

Portal_plant_winter_annual_19892002.csv

Portal_plant_winter_perennial_19892002.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 24 year period (1983–2002) of detailed annual and herbaceous perennial plant sampling of an arid ecosystem in near Portal, Arizona. Each year rooted plants are counted within 16 fixed quadrats on each of 24 experimental plots. The data set should prove useful for studying population dynamics and species interactions. Sampling is ongoing and data will be added over time.

D. Key words: annual plants, arid ecosystem, climate, competition, granivory, perennials.

CLASS II. RESEARCH ORIGIN DESCRIPTORS

A. Overall project description

Identity: Quadrat-based survey data of a desert plant community conducted in winter and summer on the 24 experimental plots at the 20-ha study site in the Chihuahuan Desert near Portal, AZ.

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

Period of Study: 1978–2002

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

Source(s) of funding: See main metadata file 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.

On each plot there are 16 permanent stations marked by rebar stakes forming a 4 × 4 grid. Rows are numbered 1,3,5,7 going from the most northern row to the most southern. Columns are numbered 1,3,5,7 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 Portal_metadata_overview.html, Fig 1). The numbering of the plant stakes reflects that each plant stake is 1 m south of the rodent/ant stake of the same number. 

Description of Winter Communities:  The first winter annuals typically germinate in response to the first autumn rains in October or November but there tends to be considerable variation among winter species in the timing of germination and initial growth.  Maximum flowering occurs in late spring (late March/early April) and all annual species (except biennials) senesce by May. 

Description of Summer Communities: Typically, germination of summer annuals begins within a few days of the first summer rains in late June or early July. Maximum flowering typically occurs in late August or early September and annual plants senesce by October.

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

Data Collection Period, Frequency: Plant data were collected continuously from 1978–2002. We have decided not to publish the data from 1978–1982 because of a variety of documented issues (Samson et al. 1992, Davidson et al. 1985, Quo et al. 2002). Contact Thomas J. Valone ([email protected]) for access to the 1978–1982 data.

Because there are two annual plant communities – one in the winter and one in the summer - there are two plant surveys per year. The surveys occur towards the end of the growing season; occurring in spring for the winter community and fall for the summer community. Perennials occurring on quadrats were also recorded.

Pre and Post 1988 differences: Before 1988, it is possible that abundances were not necessarily recorded for all species present on a quadrat. Various assessments of the pre-1989 data have suggested that data may not have been collected on the rare species (Samson et al. 1992, Davidson et al. 1985, Quo et al. 2002), but when the transition to complete community sampling occurred is not clear. We are confident that complete community sampling was occurring by 1989. Therefore, we have split the plant data into two files reflecting this possible quality issue: 1983–1988 and 1989–2002. Data for perennial and annual plants are located in separate files. Although population analyses of specific species may be possible using both time periods, community-level analyses (e.g., species richness) involving both pre and post 1989 data should be conducted with extreme caution.

3. Research Methods

Field: Plants rooted within 16 fixed quadrats in each plot are counted each spring (winter annual survey) and fall (summer annual survey). Quadrat dimensions: 0.25 × 0.25 m. Quadrats are placed at locations permanently marked by a rebar stake.

Taxonomy and systematics: Kearney, T. H., and R. H. Peebles. 1960. Arizona Flora. University of California Press. Berkeley, California, USA.

4. Project personnel:  Unfortunately, our records of personnel involved with data collection are scarce. To the best of our knowledge, the following people were principally involved in data collection: Ginger Allington , Kristina Ernest, Keith Geluso, Richard Inouye, Margaret Kurzius, Jennifer Meyer , Qinfeng Guo, Dov Sax, Michele Schutzenhofer, Stephan Sommer, and  Thomas Valone. Some 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: Plant identifications are verified, in the field, by checking a reference collection of plants from the site. Unknown species are collected for later identification. Data entered into the computer are checked by two people to ensure reliable data entry. Voucher specimens for many species were deposited at Garrett Herbarium at the Utah Museum of Natural History (Davidson et al. 1985).

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 T. J. Valone and a copy with S. K. M. Ernest. Original datasheets reside with T. J. Valone.

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

Copyright restrictions: None.

Proprietary restrictions: None. However, we do request that authors of publications using the plant database cite the database according to Ecological Archives policy and notify Thomas J. Valone (contact information above) of publication of their study. This allows 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-1989 SUMMER ANNUAL PLANT SURVEY

A. Data Set File:

Identity: Portal_plant_summer_annual_19831988.csv

Size: 2305 rows (including header), 528 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_plant_summer_annual_19831988.csv
Each row contains information on the number of individuals of each species surveyed on a particular quadrat during a particular year.

PRE-1989 SUMMER PERENNIAL PLANT SURVEY

A. Data Set File:

Identity: Portal_plant_summer_perennial_19831988.csv

Size: 2305 rows (including header), 554 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_plant_summer_perennial_19831988.csv
Each row contains information on the number of individuals of each species surveyed on a particular quadrat during a particular year.

PRE-1988 WINTER ANNUAL PLANT SURVEY

A. Data Set File:

Identity: Portal_plant_winter_annual_19831988.csv

Size: 2305 rows (including header), 491 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_plant_winter_annual_19831988.csv

PRE-1988 WINTER HERBACEOUS PERENNIAL PLANT SURVEY

A. Data Set File:

Identity: Portal_plant_winter_perennial_19831988.csv

Size: 2305 rows (including header row), 451 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 4. Column information for Portal_plant_winter_perennial_19831988.csv

POST-1988 SUMMER ANNUAL PLANTS

A. Data Set File:

Identity: Portal_plant_summer_annual_19892002.csv

Size: 5377 rows (including header), 789 Kilobyte

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 5. Column information for Portal_plant_summer_annual_19892002.csv
Each row contains information on the number of individuals of each species surveyed on a particular quadrat during a particular year.

POST-1988 SUMMER HERBACEOUS PERENNIAL PLANTS

A. Data Set File:

Identity: Portal_plant_summer_perennial_19892002.csv

Size: 5377 rows (including header), 792 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 6. Column information for Portal_plant_summer_perennial_19892002.csv
Each row contains information on the number of individuals of each species surveyed on a particular quadrat during a particular year.

POST-1988 WINTER ANNUAL PLANTS

A. Data Set File:

Identity: Portal_plant_winter_annual_19892002.csv

Size: 5377 rows (including header), 801 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 7. Column information for Portal_plant_winter_annual_19892002.csv
Each row contains information on the number of individuals of each species surveyed on a particular quadrat during a particular year.

POST-1988 WINTER HERBACEOUS PERENNIAL PLANTS

A. Data Set File:

Identity: Portal_plant_winter_perennial_19892002.csv

Size: 5377 rows (including header), 664 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 8. Column information for Portal_plant_winter_perennial_19892002.csv
Each row contains information on the number of individuals of each species surveyed on a particular quadrat during a particular year.

Table 9. Plant species codes, scientific names, and annual vs. perennial

CLASS V. SUPPLEMENTAL DESCRIPTORS

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