Plant Assessment Form

More Centaurea solstitialis resources

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 committee 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. Severe

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? Consider the impact on the natural range and variation of abiotic ecosystem processes and system-wide parameters in ways that significantly diminish the ability of native species to survive and reproduce. Alterations that determine the types of communities that can exist in a given area are of greatest concern. Examples of abiotic processes include: - fire occurrence, frequency, and intensity; - geomorphological changes such as erosion and sedimentation rates; - hydrological regimes, including soil water table; - nutrient and mineral dynamics, including salinity, alkalinity, and pH; - light availability (e.g. when an aquatic invader covers an entire water body that would otherwise be open). Select the one letter below that best describes this species' most severe impact on an abiotic ecosystem process: A. Severe, possibly irreversible, alteration or disruption of an ecosystem process. B. Moderate alteration of an ecosystem process. C. Minor alteration of an ecosystem process. D. Negligible perceived impact on an ecosystem process. U. Unknown.	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? Consider the cumulative ecological impact of this species to the plant communities it invades. Give more weight to changes in plant composition, structure, and interactions that involve rare or keystone species or rare community types. Examples of severe impacts include: - formation of stands dominated (>75% cover) by the species; - occlusion (>75% cover) of a native canopy, including a water surface, that eliminates or degrades layers below; - significant reduction or extirpation of populations of one or more native species. Examples of impacts usually less than severe include: - reduction in propagule dispersal, seedling recruitment, or survivorship of native species; - creation of a new structural layer, including substantial thatch or litter, without elimination or replacement of a pre-existing layer; - change in density or depth of a structural layer; - change in horizontal distribution patterns or fragmentation of a native community; - creation of a vector or intermediate host of pests or pathogens that infect native plant species. Select the one letter below that best describes this species' impact on community composition, structure and interactions: A. Severe alteration of plant community composition, structure, or interactions. B. Moderate alteration of plant community composition. C. Minor alteration of community composition. D. Negligible impact known; causes no perceivable change in community composition, structure, or interactions. U. Unknown.	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? Consider the cumulative impact of this species on the animals, fungi, microbes, and other organisms in the communities that it invades. Although a non-native species may provide resources for one or a few native species (e.g. by providing food, nesting sites, etc.), the ranking should be based on the species' net impact on all native species. Give more weight to changes in composition and interactions involving rare or keystone species or rare community types. Examples of severe impacts include: - extirpation or endangerment of an existing native species or population; - elimination or significant reduction in native species' nesting or foraging sites, cover, or other critical resources (i.e., native species habitat), including migratory corridors. Examples of impacts that are usually less than severe include: - minor reduction in nesting or foraging sites, cover, etc. for native animals; - minor reduction in habitat connectivity or migratory corridors; - interference with native pollinators; - injurious components, such as awns or spines that damage the mouth and gut of native wildlife species, or production of anti-digestive or acutely toxic chemical that can poison native wildlife species. Select the one letter below that best describes this species' impact on community composition and interactions: A. Severe alteration of higher trophic populations, communities, or interactions. B. Moderate alteration of higher trophic level populations, communities, or interactions. C. Minor alteration of higher trophic level populations, communities or interactions. D. Negligible impact; causes no perceivable change in higher trophic level populations, communities, or interactions. E. Unknown.	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? Consider whether the species can hybridize with and influence the proportion of individuals with non-native genes within populations of native species. Mechanisms and possible outcomes include: - production of fertile or sterile hybrids that can outcompete the native species; - production of sterile hybrids that lower the reproductive output of the native species. Select the one letter below that best describes this species' impact on genetic integrity: A. Severe (high proportion of individuals). B. Moderate (medium proportion of individuals). C. Minor (low proportion of individuals). D. No known hybridization. U. Unknown.	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? Assess this species' dependence on disturbance: both human and natural: for establishment in wildlands. Examples of anthropogenic disturbances include: - grazing, browsing, and rooting by domestic livestock and feral animals; - altered fire regimes, including fire suppression; - cultivation; - silvicultural practices; - altered hydrology due to dams, diversions, irrigation, etc.; - roads and trails; - construction; - nutrient loading from fertilizers, runoff, etc. Examples of natural disturbance include: - wildfire; - floods; - landslides; - windthrow; - native animal activities such as burrowing, grazing, or browsing. Select the first letter in the sequence below that describes the ability of this species to invade wildlands: A. Severe invasive potential: this species can establish independent of any known natural or anthropogenic disturbance. B. Moderate invasive potential: this species may occasionally establish in undisturbed areas but can readily establish in areas with natural disturbances. C. Low invasive potential: this species requires anthropogenic disturbance to establish. D. No perceptible invasive potential: this species does not establish in wildlands (though it may persist from former cultivation). U. Unknown.	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? Assess this species' rate of spread in existing localized infestations where the proportion of available habitat invaded is still small when no management measures are implemented. Select the one letter below that best describes the rate of spread: A. Increases rapidly (doubling in <10 years) B. Increases, but less rapidly C. Stable D. Declining U. Unknown	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? Assess the overall trend in the total area infested by this species statewide. Include current management efforts in this assessment and note them. Select the one letter below that best describes the current trend: A. Increasing rapidly (doubling in total range statewide in <10 years) B. Increasing, but less rapidly C. Stable D. Declining U. Unknown	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? Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.	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? Assess whether this species is currently spread: or has high potential to be spread: by direct or indirect human activity. Such activity may enable the species to overcome natural barriers to dispersal that would not be crossed otherwise, or it may simply increase the natural dispersal of the species. Possible mechanisms for dispersal include: - commercial sales for use in agriculture, ornamental horticulture, or aquariums; - use as forage, erosion control, or revegetation; - presence as a contaminant (seeds or propagules) in bulk seed, hay, feed, soil, packing materials, etc.; - spread along transportation corridors such as highways, railroads, trails, or canals; - transport on boats or boat trailers. Select the one letter below that best describes human-caused dispersal and spread: A. High: there are numerous opportunities for dispersal to new areas. B. Moderate: human dispersal occurs, but not at a high level. C. Low: human dispersal is infrequent or inefficient. D. Does not occur. U. Unknown.	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? We have chosen 1 km as the threshold of "long-distance." Assess whether this species is frequently spread, or has high potential to be spread, by animals or abiotic mechanisms that can move seed, roots, stems, or other propagules this far. The following are examples of such natural long-distance dispersal mechanisms: - the species' fruit or seed is commonly consumed by birds or other animals that travel long distances; - the species' fruits or seeds are sticky or burred and cling to feathers or hair of animals; - the species has buoyant fruits, seeds, or other propagules that are dispersed by flowing water; - the species has light propagules that promote long-distance wind dispersal; - The species, or parts of it, can detach and disperse seeds as they are blown long distances (e.g., tumbleweed). Select the one letter below that best describes natural long-distance dispersal and spread: A. Frequent long-distance dispersal by animals or abiotic mechanisms. B. Occasional long-distance dispersal by animals or abiotic mechanisms. C. Rare dispersal more than 1 km by animals or abiotic mechanisms. D. No dispersal of more than 1 km by animals or abiotic mechanisms. U. Unknown.	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? Assess whether this species has invaded ecological types in other states or countries outside its native range that are analogous to ecological types not yet invaded in your state (see Worksheets B, C, and D for California, Arizona, and Nevada, respectively, in Part IV for lists of ecological types). This information is useful in predicting the likelihood of further spread within your state. Select the one letter below that best describes the species' invasiveness in other states or countries, outside its native range. A. This species has invaded 3 or more ecological types elsewhere that exist in your state and are as yet not invaded by this species (e.g. it has invaded Mediterranean grasslands, savanna, and maquis in southern Europe, which are analogous to California grasslands, savanna, and chaparral, respectively). B. Invades 1 or 2 ecological types that exist but are not yet invaded in your state. C. Invades elsewhere but only in ecological types that it has already invaded in the state. D. Not known as an escape anywhere else. U. Unknown.	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? Refer to Worksheet C and select the one letter below that indicates the number of different ecological types that this species invades. A. Widespread: the species invades at least three major types or at least six minor types. B. Moderate: the species invades two major types or five minor types. C. Limited: the species invades only one major type and two to four minor types. D. Narrow: the species invades only one minor type. U. Unknown.	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? To assess distribution, record the letter that corresponds to the highest percent infested score entered in Worksheet C for any ecological type.	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? Scoring Criteria for Worksheet A A. High reproductive potential (6 or more points). B. Moderate reproductive potential (4-5 points). C. Low reproductive potential (3 points or less and less than 3 Unknowns). U. Unknown (3 or fewer points and 3 or more Unknowns).

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? A means >50% of type occurrences are invaded; B means 20% to 50%; C means 5% to 20%; D means present but <5%; U means unknown (unable to estimate percentage of occurrences invaded)
Marine Systems	marine systems
Freshwater and Estuarine	lakes, ponds, reservoirs
Aquatic Systems	rivers, streams, canals
Aquatic Systems	estuaries
Dunes	coastal
	desert
	interior
Scrub and Chaparral	coastal 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
	chaparral	B, 20% - 50%
Grasslands, Vernal Pools, Meadows, and other Herb Communities	coastal prairie	A, > 50%
	valley and foothill grassland	B, 20% - 50%
	Great Basin grassland
	vernal pool
	meadow and seep
	alkali playa
	pebble plain
Bog and Marsh	bog and fen
Bog and Marsh	marsh and swamp
Riparian and Bottomland habitat	riparian forest
	riparian woodland
	riparian scrub (incl.desert washes)	B, 20% - 50%
Woodland	cismontane woodland
	piñon and juniper woodland
	Sonoran thorn woodland
Forest	broadleaved upland forest
	North Coast coniferous forest
	closed cone coniferous forest
	lower montane coniferous forest
	upper montane coniferous forest
	subalpine coniferous forest
Alpine Habitats	alpine boulder and rock field
Alpine Habitats	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
Great Valley
Northwest
Sierra Nevada
Southwest
Modoc Plateau
Sierra Nevada East
Desert Province
Mojave Desert
Sonoran Desert

California Invasive Plant Council

Protecting California’s environment and economy from invasive plants

Plant Assessment Form

More Centaurea solstitialis resources

Centaurea solstitialis

Evaluator(s)

List committee members

General Comments

Table 2. Criteria, Section, and Overall Scores

Table 3. Documentation

Worksheet A - Innate reproductive potential

Related traits:

Worksheet C - California Ecological Types

Infested Jepson Regions