Metadata for Red Brome Spread in Western North America

MetaData for Red Brome Spread in Western North America

Cindy Salo

Herbarium Records

I included herbarium records of all red brome accessions from ten herbaria in California, Utah, and Arizona to describe the spread of red brome in western North America and determine its current range. I visited the following herbaria during the summer of 1999: University (UC) and Jepson (JEPS) Herbaria, University of California, Berkeley, CA; University of California at Davis Herbarium (DAV), Davis, CA; Garrett Herbarium (UT), University of Utah, Salt Lake City, UT; Intermountain Herbarium (UTC), Utah State University, Logan, UT; Brigham Young University Herbarium (BRY), Provo, UT; U.S. Forest Service Rocky Mountain Research Station Herbarium (OGDF), Ogden, UT; University of Arizona Herbarium (ARIZ), Tucson, AZ; Arizona State University Plant Herbarium (ASU), Tempe, AZ; and Deaver Herbarium (ASC), Northern Arizona University, Flagstaff, AZ. I obtained additional records of red brome collections in California from the on-line CalFlora Occurrence Database (UC Berkeley 1999) during the summer of 1999.

The U.S. Geological Survey’s (USGS) Geographic Names Information System (GNIS) on-line database (USGS 2000) provided coordinates for geographic features in many collection location descriptions. I verified latitude and longitude of all features using topographic atlases and extrapolated to collection locations and elevations on these maps. I used the following topographic atlases: Southern and Central California (DeLorme Mapping Co. 1998), Northern California, scale 1:150,000 (DeLorme Mapping Co. 1995), Utah, scale 1:250,000 (DeLorme Mapping Co. 1993), Nevada, scale ca. 1:300,000 (Nev. Dept. of Highways 1984), Arizona, scale 1:250,000 (DeLorme Mapping Co. 1993), Grand Canyon National Park, scale 1:62,500 (USGS 1967), New Mexico, scale 1:500,000 (Benchmark Maps 1995), and Baja California Norte, Mexico, scale ca. 1:108,000 (Topography International 1986).

When legal descriptions were given in collection locations, I used the latitude and longitude of the center of the survey section, obtained from the township, range, and survey section, using an on-line program (Wefald 2000). When collectors provided latitude and longitude from Global Positioning System (GPS) units, I used their locations. I obtained city locations for the California missions from the California Missions web page (Anon. undated), then obtained latitude and longitude for these cities from the USGS GNIS On-line Database (USGS 2000).

I recorded collection information from 995 herbarium specimens of red brome. I then eliminated 95 that did not include sufficient information to allow me to determine location within 10 km (5 km in either direction), 11 that did not include at least the month of collection, 13 cultivated specimens, seven specimens collected outside the conterminous United States or Mexico, 114 duplicate collections deposited at multiple herbaria, and 67 collections from a previous location (same wording of location description) at a later date. The remaining 688 locations were mapped to describe the spread of red brome in western North America.

Mapping Red Brome

I mapped 688 red brome collections in western North America using ArcView 3.2 GIS software (ESRI 1999) with an equidistant conic projection (Clarke spheroid of 1866), a central meridian of –115, reference latitude of 37, and standard parallels of 32 and 42. From this map I extracted coordinates, with units of kilometers, for each collection location, which I used to determine the increase in area occupied by red brome over time. Working from kilometer coordinates eliminated problems associated with the variable distance between lines of longitude at different latitudes. I eliminated collections that occurred within 50 km of earlier collections using the Pythagorean Theorem in Excel 2000 (Microsoft 1999). The remaining collections represented new 50-km areas occupied by red brome, which I used to map the spread of red brome in western North America.

Determining the increase in area occupied over time is preferred to determining the increase in number of collections, as it avoids the inherent confounding of number of herbarium records with changes in density (Auld et al. 1982) and collecting activity (Roy et al. 1991). This approach is also preferred to determining the increase in geopolitical units, such as counties, occupied by a species over time, as these entities vary in area (Forcella 1985).

Literature Cited

Anonymous (Undated) California Missions Website http://missions.bgmm.com/index.html. Last visited 26 December 2001

Auld BA, Hosking J, McFadyen RE (1982) Analysis of the spread of tiger pear and parthenium weed in Australia. Australian Weeds 2: 56-60

Benchmark Maps (1995) New Mexico Road and Recreation Atlas. Benchmark Maps, Berkeley, CA, 96 pp

DeLorme Mapping Company (1993) Arizona Atlas and Gazetteer, scale 1:250,000. DeLorme, Freeport, ME, 76 pp

DeLorme Mapping Company (1993) Utah Atlas and Gazetteer, scale 1:250,000. DeLorme, Freeport, ME, 74 pp

DeLorme Mapping Company (1995) Northern California Atlas and Gazetteer, 3rd edn, scale 1:150,000. DeLorme, Freeport, ME, 127 pp

DeLorme Mapping Company (1998) Southern and Central California Atlas and Gazetteer, 4th edn, scale 1:150,000. DeLorme, Yarmouth, ME, 128 pp

ESRI (Environmental System Research Institute, Inc.) (1999) ArcView GIS Package v. 3.2) ESRI, Redlands, CA

Forcella F (1985) Final distribution is related to rate of spread of alien weeds. Weed Research 25: 181-191

Microsoft (1999) Excel 2000 Spreadsheet. Microsoft Corp., Redmond, WA

Nevada Dept. of Highways, Cartographic Section (1984?) Nevada Map Atlas, scale ca. 1:300,000. Nev. Dept. Highways, Carson City, NV

Roy J, Navas ML and Sonié L (1991) Invasion by annual brome grasses: a case study challenging the homoclime approach to invasions. In Groves RH and DiCastri F (eds) Biogeography of Mediterranean invasions, pp 207-224 Cambridge University Press, Cambridge

Topography International (1986) Baja Topographic Atlas Directory, scale ca. 1:108,000. Topography International, Inc., San Clemente, CA, 259 pp

USGS (US Geological Survey) (1967). Grand Canyon National Park, scale 1:62,500. USGS, Washington, DC

USGS (US Geological Survey) (2000) Geographic Names Information System On-line Data Base. http://wwwnmd.usgs.gov/www/gnis Last visited 04 February 2002

Wefald M (2000) TRS2LL Program. http://www.esg.montana.edu/gl/trs-data.html (previous web address, http://www.crl.com/~wefald/trs2ll.html). Last visited 30 April 2001