Plant Assessment Form

Centaurea solstitialis

Common Names: yellow starthistle

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
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 Observational
1.4 ?Impact on genetic integrity D. None
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Observational
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 A. High Other Published Material
2.6 ? Potential for natural long-distance dispersal C. Rare Reviewed Scientific Publication
2.7 ?Other regions invaded C. Already invaded Reviewed Scientific Publication
3.1 ?Ecological amplitude/Range
(see Worksheet C)
B. Moderate 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:

Yellow starthistle significantly depletes soil moisture reserves in grasslands of California and Oregon. Deep root system allows starthistle to utilize deep soil moisture late into the growing season. Consequently, the next seasons soil moisture recharge is less than native perennial grasslands and annual grasslands.


Sources of information:

Enloe, S.F. 2002. PhD dissertation. UC Davis; Borman, M.M., D.E. Johnson, and W.C. Krueger. 1992. Soil moisture extraction by vegetation in a Mediterranean/Maritime climatic regime. Agronomy Journal 84:897-904; Gerlach, J.D., A. Dyer, and K.J. Rice. 1998. Grassland and foothill woodland ecosystems of the Central Valley. Fremontia 26:39-43.


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

Starthistle infestations can reduce wildlife habitat and forage, displace native plants, and decrease native plant and animal diversity. Dense infestations not only displace native plants and animals, but also threaten natural ecosystems and nature reserves by fragmenting sensitive plant and animal habitat. Because of the spiny nature of yellow starthistle, livestock and wildlife avoid grazing in heavily infested areas. In addition, yellow starthistle has been experimentally shown to have greater than 80% in heavily infested areas.


Sources of information:

DiTomaso, J.M. http://wric.ucdavis.edu/yst/impacts/impacts.html; Sheley, R.L. and L.L. Larson. 1994a. Observation: Comparative live-history of cheatgrass and yellow starthistle. Journal of Range Management 47:450-456; Roch_, B.F., Jr., C.T. Roch_, and R.C. Chapman. 1994. Impacts of grassland habitat on yellow starthistle (Centaurea solstitialis L.) invasion. Northwest Science 68:86-96.


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

Probably reduces wildlife forage once it produces spines. Because of the spiny nature of yellow starthistle and its negative impact on livestock grazing, it is expected that it would have a similar impact on my wildlife species.


Sources of information:

DiTomaso, J.M. http://wric.ucdavis.edu/yst/impacts/impacts.html; observational and anecdotal information for many sources, including DiTomaso, J.M.


Question 1.4 Impact on genetic integrity? D

None There are no native Centaurea species in California, thus it is assumed that there is no opportunity to have an impact.


Sources of information:

None


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

Any form of soil disturbance can lead to establishment of yellow starthistle. Over grazing and domination by annual grasses in open areas can also lead to establishment and dominance by yellow starthistle. Much evidence indicates that yellow starthistle can invade disturbed areas, particularly roadsides. From here it has been shown to move into grasslands that area either disturbed or undisturbed within the past several years. These grasslands have over 100 year history of disturbance and are now annual grasslands, having been converted from perennial grasslands before European settlement in the west.


Sources of information:

Gerlach, J.D., Jr. 1997b. The introduction, dynamics of geographic range expansion, and ecosystem effects of yellow starthistle (Centaurea solstitialis). Proc., California Weed Science Society 49:136-141; also see DiTomaso, J.M. http://wric.ucdavis.edu/yst for more information. Much of the evidence for movement into undisturbed sites is observational, particularly by Enloe, DiTomaso and Gerlach.


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

By 1958, it was estimated to have invaded over 1 million acres of California, much of this in range or grasslands. Today, it is thought to have spread to over 15 million acres in California, and can be found in 56 of the 58 counties in California. Over the past 40 years, yellow starthistle has spread exponentially to infest rangelands, native grasslands, orchards, vineyards, pastures, roadsides, and wasteland areas.


Sources of information:

Maddox, D.M. and A. Mayfield. 1985. Yellow starthistle infestations are on the increase. California Agriculture 39(11/12):10-12; Pitcairn, M.J., R.A. O'Connell, and J.M. Gendron. 1998b. Yellow starthistle: survey of statewide distribution. Pages 64-66. D.M. Woods, ed. In, Biological Control Program Annual Summary, 1997. California Department of Food and Agriculture, Plant Health and Pest Prevention Services, Sacramento, CA.


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

Appears to be stable or perhaps even declining a bit. The leveling out of yellow starthistle infestations in California is probably due to two factors, 1) it has nearly reached its full available range and sites, and 2) a more concerted effort by state, federal, county and local groups and private citizens to manage for yellow starthistle. However, its range and level of infestation is increasing exponentially in the western US outside of California.


Sources of information:

Observational by DiTomaso.


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

Produces seed every year at levels of 10,000 per square meter. Plant is an annual and does not reproduce vegetatively. Seeds can live for 3 or more years in the soil. Seed production and establishment are high.


Sources of information:

Many publications have documented the reproduction of yellow starthistle, as well and its seed longevity, and germination characteristics. These are summarized in DiTomaso, J.M. http://wric.ucdavis.edu/yst.


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

The movement of contaminated hay and uncertified seed are important long distance transportation mechanisms. The use of tractors and other equipment spread starthistle seed to other locations, including grain fields. Seed is transported in large amounts by road maintenance equipment and on the undercarriage of vehicles. In past several years, it is likely that yellow starthistle movement has been initially along roadsides, probably due to contaminated hay and soil. Since the 1960's three factors greatly contributed to its further spread, including extensive road building, increased suburban development, and an expansion in the ranching industry.


Sources of information:

Observations by many individuals. See DiTomaso, J.M. http://wric.ucdavis.edu/yst for more information.


Question 2.6 Potential for natural long-distance dispersal? C Reviewed Scientific Publication
Identify dispersal mechanisms:

Primarily wind blown seed. Some dispersal by birds and mammals after ingestion, but very few seed likely remain viable after passing through the digestive system. About 90% of the seed have been shown to fall within 2 ft of the parent plant.


Sources of information:

Roch_, B.F., Jr. 1992. Achene dispersal in yellow starthistle (Centaurea solstitialis L.). Northwest Science 66:62-65.


Question 2.7 Other regions invaded? C Reviewed Scientific Publication
Identify other regions:

Yellow starthistle is in grasslands throughout the Pacific Northwest states.
Today yellow starthistle can be found in most of the temperate areas around the world. All Mediterranean climates around the world are susceptible to invasion by yellow starthistle.


Sources of information:

Maddox, D.M., A. Mayfield, and N.H. Poritz. 1985. Distribution of yellow starthistle (Centaurea solstitialis) and Russian knapweed (Centaurea repens). Weed Science 33(3):315-327; Sheley, R.L., L.L. Larson, and J.S. Jacobs. 1999b. Yellow starthistle. Pages 409-416. Sheley, R.L. and J.K. Petroff, eds. In, Biology and Management of Noxious Rangeland Weeds. Oregon State University Press, Corvallis.


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

Its introduction in North America probably occurred sometime after 1849 as a seed contaminant in Chilean-grown alfalfa seed, also known as Chilean clover. Because yellow starthistle does not do well in shaded areas, it is restricted to open sites, particularly grasslands. Since grasslands of California are dominated with shallow rooted annual species, starthistle has become very competitive and can dominate these sites.


Sources of information:

Gerlach, J.D., Jr. 1997. The introduction, dynamics of geographic range expansion, and ecosystem effects of yellow starthistle (Centaurea solstitialis). Proc., California Weed Science Society 49:136-141; Gerlach, J.D., Jr. 1997. How the west was lost: reconstructing the invasion dynamics of yellow starthistle and other plant invaders of western rangelands and natural areas. Proc., California Exotic Pest Plant Council Symposium 3:67-72.


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

By 1958, it was estimated to have invaded over 1 million acres of California, much of this in range or grasslands. Today, it is thought to have spread to over 15 million acres in California, and can be found in 56 of the 58 counties in California. Primarily invades grasslands and grassland areas within oak woodlands.


Sources of information:

Maddox, D.M. and A. Mayfield. 1985. Yellow starthistle infestations are on the increase. California Agriculture 39(11/12):10-12; Pitcairn, M.J., R.A. O'Connell, and J.M. Gendron. 1998b. Yellow starthistle: survey of statewide distribution. Pages 64-66. D.M. Woods, ed. In, Biological Control Program Annual Summary, 1997. California Department of Food and Agriculture, Plant Health and Pest Prevention Services, Sacramento, CA; Gerlach, J.D., A. Dyer, and K.J. Rice. 1998. Grassland and foothill woodland ecosystems of the Central Valley. Fremontia 26:39-43.


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 Yes
Seeds remain viable in soil for three or more years Yes
Viable seed produced with both self-pollination and cross-pollination No
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 scrub
Sonoran desert scrub
Mojavean desert scrub (incl. Joshua tree woodland)
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrub
chaparralB, 20% - 50%
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairieA, > 50%
valley and foothill grasslandB, 20% - 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)B, 20% - 50%
Woodlandcismontane woodland
piñon and juniper woodland
Sonoran thorn woodland
Forestbroadleaved upland forest
North Coast coniferous forest
closed cone coniferous forest
lower montane coniferous forest
upper montane coniferous forest
subalpine coniferous forest
Alpine Habitatsalpine boulder and rock field
alpine dwarf scrub
Amplitude (breadth): B
Distribution (highest score): A

Infested Jepson Regions

Click here for a map of Jepson regions

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