Plant Assessment Form

Bromus tectorum

Common Names: cheatgrass; downy brome

Evaluated on: 2/8/03

List committee review date: 10/02/2003

Re-evaluation date:

Evaluator(s)

Joe DiTomaso
UC Davis
Weed Science Program, Robbins Hall, Univ. California, Davis CA 95616
530-754-8715
DiTomaso@vegmail.ucdavis.edu

List commitee members

Carla Bossard
John Randall
Peter Warner
Doug Johnson
John Hall
Dana Backer
Cindy Roye
Matt Brooks

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? High
Alert Status? No Alert
Documentation? 3 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes A Reviewed Scientific Publication
Impact?
Four-part score AABD Total Score
A
1.2 ?Impact on plant community A. Severe Reviewed Scientific Publication
1.3 ?Impact on higher trophic levels B. Moderate Reviewed Scientific Publication
1.4 ?Impact on genetic integrity D. None
2.1 ?Role of anthropogenic and natural disturbance in establishment A. Severe Other Published Material
Invasiveness?
Total Points
14 Total Score B
2.2 ?Local rate of spread with no management A. Increases rapidly Reviewed Scientific Publication
2.3 ?Recent trend in total area infested within state C. Stable Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
A. High Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal B. Moderate Other Published Material
2.6 ? Potential for natural long-distance dispersal C. Rare Other Published Material
2.7 ?Other regions invaded C. Already invaded Other Published Material
3.1 ?Ecological amplitude/Range
(see Worksheet C)
A. Widespread Other Published Material
Distribution?
Total Score A
3.2 ?Distribution/Peak frequency
(see Worksheet C)
A. High Other Published Material

Table 3. Documentation

Scores are explained in the "Criteria for Categorizing Invasive Non-Native Plants that Threaten Wildlands".

Section 1: Impact
Question 1.1 Impact on abiotic ecosystem processes? A Reviewed Scientific Publication
Identify ecosystem processes impacted:

Changes the frequency, extent, and timing of wildfires. In many areas that have been invaded by cheatgrass the natural fire cycle has shortened from every 60-100 years to every 3-5 years. Early fine fuel of downy brome forms a continuum between shrubs and bunchgrasses allowing fires to carry farther. The shorter fire frequency has eliminated many shrubs in these communities. As fires become even more frequent, the area will be dominated by annual grasses alone, with the loss of surface soil, nutrients, and near permanent deterioration of the site.


Sources of information:

Young, J. 2000. Bromus tectorum. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, M. Hoshovsky. UC Press, Berkeley; Whisenant, S.G. 1990. Changing fire frequencies on Idahos Snake River Plains. USDA For. Ser. Gen Tech. Rep INT-276, 4-10; West, N.E. 1979. Basic synecological relationships of sagebrush-dominated lands in the Great Basin and the Colorado Plateau. Pp. 33-41 In Anon. The Sagebrush Ecosystem: A Symposium, Utah State University, College of Natural Resources, Logan, Utah; Whisenant, S.G. 1989. Changing fire frequencies on Idaho's Snake River Plains: Ecological and management implications. Proceedings-Symposium on Cheatgrass Invasion, Shrub Die-off, and Other Aspects of Shrub Biology and Management. General Technical Report INT-276 Forest Service Intermountain Research Station, November 1990; Many others papers, see Mosley, J.C., S.C. Bunting and M.E. Manoukian. 1999. Cheatgrass. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff. Oregon State Univ. Press, Corvallis for review and other citations.


Question 1.2 Impact on plant community composition,
structure, and interactions?
A Reviewed Scientific Publication
Identify type of impact or alteration:

Can displace native vegetation by outcompeting them for soil moisture. Downy brome is well adapted to fire and often dominates plant communities after fire (Melgoza et al. 1990). Changes in fire frequency can complete alter vegetation and lead to monotypic stands of downy brome.


Sources of information:

Melgoza, G., R.S. Nowak, and R.J. Tausch. 1990. Soil water exploitation after fire: Competition between Bromus tectorum (cheatgrass) and two native species. Oecologia 83:7-13; Young, J. 2000. Bromus tectorum. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, M. Hoshovsky. UC Press, Berkeley; Many others papers, see Mosley, J.C., S.C. Bunting and M.E. Manoukian. 1999. Cheatgrass. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff. Oregon State Univ. Press, Corvallis for review and other citations.


Question 1.3 Impact on higher trophic levels? B Reviewed Scientific Publication
Identify type of impact or alteration:

Has had a negative effect on wildlife, particularly due to change in fire frequency. Does have a positive impact of forage for wildland in spring. Slow-moving fauna such as desert tortoises are sometimes killed in the rapidly moving fires. The effects on native game species are largely unknown, but expected to be similar to livestock.


Sources of information:

Young, J. 2000. Bromus tectorum. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, M. Hoshovsky. UC Press, Berkeley


Question 1.4 Impact on genetic integrity? D

Hybridization with other species rarely occurs under natural conditions. Unlikely to hydridize with other native Bromus species. No evidence that this has occurred.


Sources of information:

Upadhaya, M.K., R. Turkington, and D. McIlvride. 1986. The biology of Canadian weeds. 75. Bromus tectorum L. Canadian Journal of Plant Science 66:689-709; Rice, K.J., and R.N. Mack. 1991. Ecological genetics of Bromus tectorum: intraspecific variation in phenotypic plasticity. Oecologia 88:84-90.


Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
A Reviewed Scientific Publication
Describe role of disturbance:

Cultivation and subsequent land abandonment, excessive livestock grazing and repeated fires can all interact to proliferate downy brome. However, it can also thrive in areas that have never been cultivated or grazed by domestic livestock. Movement into grasslands and scrublands appear to be initially in disturbed areas, but it is then capable of moving into undisturbed sites. In undisturbed sites, cheatgrass will most commonly spread along soil cracks and work its way outward into the natural community.


Sources of information:

See Mosley, J.C., S.C. Bunting and M.E. Manoukian. 1999. Cheatgrass. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff. Oregon State Univ. Press, Corvallis for review and other citations; Douglas, B.J., A.G. Thomas and D. A. Derksen. 1990. Downy brome (Bromus tectorum) invasion into southwestern Saskatchewan. Canadian J. Plant Sci. 70:1143-1151; Rice, K.J., and R.N. Mack. 1991. Ecological genetics of Bromus tectorum: A hierarchical analysis of phenotypic variation. Oecologia 88:77-83.


Question 2.2 Local rate of spread with no management? A Reviewed Scientific Publication
Describe rate of spread:

Can double in less than 10 years. Because downy brome now occupies 100 million acres in the US and was only introduced a bit over 100 years ago, it is clear that it is capable of doubling its infestation level within 10 years.


Sources of information:

Mosley, J.C., S.C. Bunting and M.E. Manoukian. 1999. Cheatgrass. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff. Oregon State Univ. Press, Corvallis.


Question 2.3 Recent trend in total area infested within state? C Observational
Describe trend:

Probably is remaining stable throughout the west, including California. Because it has occupied the full extent of its range, it is likely to be stable at this time.


Sources of information:

Observational information.


Question 2.4 Innate reproductive potential? A Reviewed Scientific Publication
Describe key reproductive characteristics:

Young, J. 2000. Bromus tectorum. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, M. Hoshovsky. UC Press, Berkeley; Mosley, J.C., S.C. Bunting and M.E. Manoukian. 1999. Cheatgrass. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff. Oregon State Univ. Press, Corvallis; Young, J.A. and R.A. Evans. 1985. Demography of Bromus tectorum in Artemisia communities. In: J. White (ed.). The Population Structure of Vegetation. Dr. W. Junk Publishers, Dordrecht, Netherlands; Upadhaya, M.K., R. Turkington, and D. McIlvride. 1986. The biology of Canadian weeds. 75. Bromus tectorum L. Canadian Journal of Plant Science 66:689-709.


Sources of information:

Spread by attachment to human clothing or by clinging to hair and fur of livestock. Contaminated grain seed probably was the early method of dispersal. Seeds can also be dispersed as a contaminant in hay and straw or by mud clinging to machinery. Not as important in downy brome at it is in other longer awned annual grasses.


Question 2.5 Potential for human-caused dispersal? B Other Published Material
Identify dispersal mechanisms:

Spread by attachment to human clothing or by clinging to hair and fur of livestock. Contaminated grain seed probably was the early method of dispersal. Seeds can also be dispersed as a contaminant in hay and straw or by mud clinging to machinery. Not as important in downy brome at it is in other longer awned annual grasses.


Sources of information:

Young, J. 2000. Bromus tectorum. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, M. Hoshovsky. UC Press, Berkeley; Mosley, J.C., S.C. Bunting and M.E. Manoukian. 1999. Cheatgrass. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff. Oregon State Univ. Press, Corvallis


Question 2.6 Potential for natural long-distance dispersal? C Other Published Material
Identify dispersal mechanisms:

Spread by wind, attachment to animal fur, or by small rodents. Animals can also transport seed in their feces and hooves. Movement by natural means probably not very long distance.


Sources of information:

Young, J. 2000. Bromus tectorum. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, M. Hoshovsky. UC Press, Berkeley


Question 2.7 Other regions invaded? C Other Published Material
Identify other regions:

Has invaded other areas of Europe, southern Russia, west central Asia, most of North America, Japan, South Africa, Australia, New Zealand, Iceland, and Greenland. Native to southern Europe, northern Africa, and southwestern Asia. One of the most widely invasive species around the world.


Sources of information:

Young, J. 2000. Bromus tectorum. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, M. Hoshovsky. UC Press, Berkeley; Mosley, J.C., S.C. Bunting and M.E. Manoukian. 1999. Cheatgrass. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff. Oregon State Univ. Press, Corvallis; Upadhaya, M.K., R. Turkington, and D. McIlvride. 1986. The biology of Canadian weeds. 75. Bromus tectorum L. Canadian Journal of Plant Science 66:689-709.


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? A Other Published Material

First introduced to the US in 1861 into the east coast and first found in California around Yosemite in 1900. Most common in sagebrush/bunchgrass communities, although its distribution extends to higher-elevation juniper, pinyon-juniper, and pine woodlands.


Sources of information:

Young, J. 2000. Bromus tectorum. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, M. Hoshovsky. UC Press, Berkeley; Mosley, J.C., S.C. Bunting and M.E. Manoukian. 1999. Cheatgrass. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff. Oregon State Univ. Press, Corvallis


Question 3.2 Distribution/Peak frequency? A Other Published Material
Describe distribution:

Widespread throughout California. Dominant annual grass on sagebrush rangelands on the Modoc Plateau and along the eastern Sierra Nevada to Owens Valley. Also in the coniferous forest zone. Widespread throughout the Great Basin. Less common in valley grasslands. Most common introduced annual grass in the United States. Today, Bromus tectorum is the dominant species on more than 100 million acres of the Intermountain west. Although Bromus tectorum can be found in both disturbed and undisturbed shrub-steppe and intermountain grasslands (e.g., where dominant grasses are Agropyron spicatum = Pesudorogneria spicata and Festuca idahoensis), the largest infestations are usually found in disturbed shrub-steppe areas, overgrazed rangeland, abandoned fields, eroded areas, sand dunes, road verges, and waste places.


Sources of information:

Young, J. 2000. Bromus tectorum. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, M. Hoshovsky. UC Press, Berkeley; Mosley, J.C., S.C. Bunting and M.E. Manoukian. 1999. Cheatgrass. In, Biology and Management of Noxious Rangeland Weeds. Eds. R.L. Sheley and J.K. Petroff. Oregon State Univ. Press, Corvallis; Whisenant, S.G. 1989. Changing fire frequencies on Idaho's Snake River Plains: Ecological and management implications. Proceedings-Symposium on Cheatgrass Invasion, Shrub Die-off, and Other Aspects of Shrub Biology and Management. General Technical Report INT-276 Forest Service Intermountain Research Station, November 1990; Carpenter, A.T. and T.A. Murray. 2002. Bromus tectorum. The Nature Conservancy. Element Stewardship Abstract http://tncweeds.ucdavis.edu/esadocs/documnts/bromtec.html


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter Yes
Populations of this species produce seeds every year. Yes
Seed production sustained over 3 or more months within a population annually No
Seeds remain viable in soil for three or more years Yes
Viable seed produced with both self-pollination and cross-pollination Yes
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes No
Fragments easily and fragments can become established elsewhere No
Resprouts readily when cut, grazed, or burned No
Total points: 7
Total unknowns: 0
Total score: A?

Related traits:

Worksheet B - Arizona Ecological Types is not included here

Worksheet C - California Ecological Types

(sensu Holland 1986)
Major Ecological Types Minor Ecological Types Code?
Marine Systemsmarine systems
Freshwater and Estuarine lakes, ponds, reservoirs
Aquatic Systemsrivers, streams, canals
estuaries
Dunescoastal
desert
interior
Scrub and Chaparralcoastal bluff scrub
coastal scrubD, < 5%
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrubA, > 50%
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparralD, < 5%
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairieC, 5% - 20%
valley and foothill grasslandA, > 50%
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swamp
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)
Woodlandcismontane woodlandB, 20% - 50%
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forestC, 5% - 20%
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): A
Distribution (highest score): A

Infested Jepson Regions

Click here for a map of Jepson regions

  • Cascade Range
  • Central West
  • Great Valley
  • Northwest
  • Sierra Nevada
  • Southwest
  • Modoc Plateau
  • Sierra Nevada East
  • Desert Province
  • Mojave Desert
  • Sonoran Desert