Plant Assessment Form

More Robinia pseudoacacia resources

Robinia pseudoacacia

Common Names: black locust

Evaluated on: 12/22/04

List committee review date: 11/03/2005

Re-evaluation date:

Evaluator(s)

Elizabeth Brusati, project manager
California Invasive Plant Council
1442A Walnut St. #462, Berkeley, CA 94709
510-843-3902
edbrusati@cal-ipc.org

List committee members

Joe DiTomaso
John Randall
Carla Bossard

General Comments

No general comments for this species

Table 2. Criteria, Section, and Overall Scores

Overall Score? Limited

Alert Status? No Alert

Documentation? 2.5 out of 5

Score

Documentation

1.1

?Impact on abiotic ecosystem processes

C. Minor

Reviewed Scientific Publication

Impact?
Four-part score CCUD Total Score
C

1.2

?Impact on plant community

C. Minor

Other Published Material

1.3

?Impact on higher trophic levels

U. Unknown

1.4

?Impact on genetic integrity

D. None

Reviewed Scientific Publication

2.1

?Role of anthropogenic and natural disturbance in establishment

B. Moderate

Reviewed Scientific Publication

Invasiveness?
Total Points
11 Total Score B

2.2

?Local rate of spread with no management

C. Stable

2.3

?Recent trend in total area infested within state

C. Stable

2.4

?Innate reproductive potential
(see Worksheet A)

B. Moderate

2.5

?Potential for human-caused dispersal

A. High

Reviewed Scientific Publication

2.6

? Potential for natural long-distance dispersal

C. Rare

Other Published Material

2.7

?Other regions invaded

C. Already invaded

Observational

3.1

?Ecological amplitude/Range
(see Worksheet C)

A. Widespread

Reviewed Scientific Publication

Distribution?
Total Score B

3.2

?Distribution/Peak frequency
(see Worksheet C)

D. Very low

Reviewed Scientific Publication

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.	C Reviewed Scientific Publication
Identify ecosystem processes impacted: Nitrogen cycling, light availability. However, infestations in California are too small to have these effects. Nitrogen-fixing tree that increases the concentration of NO3 in the soil. Fixed N is accumulated as biomass and enters the soil only in older (38yr) stands (1). Tall tree (100 ft), so creates shade where it invades open areas Sources of information: 1. Boring L. R., Swank W. T. 1984. The Role of Black Locust (Robinia pseudoacacia) in Forest Succession. Journal of Ecology. 72: 749-766. 2. Hunter, J. Robinia pseudoacacia. pp. 273-276 in Bossard, C. M., J. M. Randall, and M. C. Hoshovsky (ed.) Invasive plants of California's wildlands. University of California Press. Berkeley, CA.
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.	C Other Published Material
Identify type of impact or alteration: Displaces native vegetation (1) but forms only patches in California. Sources of information: 1. Hunter 2000
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.	U
Identify type of impact or alteration: Poisonous to livestock but they rarely eat it. No information on impacts to native species. Sources of information: 1. Kingsbury J. M. 1964. Poisonous Plants of the United Sates and Canada. Prentice Hall Inc. New Jersey.
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 Reviewed Scientific Publication
Possibility of hybridization with one related native tree (R. neomexicana) but this seems unlikely because the native inhabits drier areas and is uncommon, and R. pseudoacacia reproduces mostly by suckers rather than seed. One closely-related California native Sources of information: Hickman, J. C. (ed.) 1993. The Jepson Manual, Higher Plants of California. University of California Press. Berkeley, CA
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.	C
Describe role of disturbance: Needs open areas for colonization . Early successional species that grows best on clear-cuts, abandoned pastures, or roadsides (1). Can invade undisturbed sand prairies (2). Sources of information: 1. Boring and Swank 1984 2. Converse C. K. 1984 Elemental Species Abstract for Robinia pseudoacacia, The Nature Conservancy. Washington, D. C. http://tncweeds.ucdavis.edu/esadocs.html
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	C
Describe rate of spread: This species has been in California for many years but has not spread significantly. Sources of information:
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
Describe trend: Consensus of weed committee is that populations in California are stable. Sources of information:
Question 2.4 Innate reproductive potential? Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.	B
Describe key reproductive characteristics: Can reproduce from seeds, but mostly reproduces by suckers or sprouting from roots. Can grow to 8m within 3 yrs (1). Begins producing seeds at year 6, with best crops between ages 15-40. Heavy seed crops at 1-2 year intervals, and light crops in between. Produces 16,000 - 35,000 per pound of seed pods. Seedling reproduction is rare (2). Seeds disperse by wind or gravity (3) Sources of information: 1. Boring and Swank 1984 2. Roach B. A. 1958 Silvical Characteristics of Black Locust. U. S. Department of Agriculture Forest Service. 1-15. 3. Hunter 2000
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 Reviewed Scientific Publication
Identify dispersal mechanisms: Planted for cultivation (1, 2) and landscaping. Has been used for panelling, construction, firewood, fenceposts, livestock forage, and nectar for honey production (2). Sources of information: 1. Hunter 2000 2. Roach 1958
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 Other Published Material
Identify dispersal mechanisms: Some seeds dispersed by wind, but as most reproduction is by suckers, this is probably a limited means of dispersal. Sources of information: 1. Hunter 2000 2. Roach 1958
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 Observational
Identify other regions: Cultivated as a horticultural species, but rarely escapes. Sources of information: Joe DiTomaso, UC Davis, and John Randall, The Nature Conservancy Invasive Species Initiative, pers. Obs.
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.	A Reviewed Scientific Publication
Mostly inhabits disturbed sites. Early successional species, needs open areas (1). Invades dry prairies, sand prairies and savannas (2). Widespread in northern California below 6300 ft, also common in Great Basin area (3). Found in disturbed woodlands and ravines in Tahoe National Forest and John Muir National Monument (4). Sources of information: 1. Boring and Swank 1984 2. Converse 1984 3. Hickman 1993 4. Hunter 2000
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.	D Reviewed Scientific Publication
Describe distribution: Present only in small patches in California. Sources of information: Joe DiTomaso, UC Davis, and John Randall, The Nature Conservancy Invasive Species Initiative, pers.obs.

Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less	No
Dense infestations produce >1,000 viable seed per square meter	No
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	Unknown
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes	Yes
Fragments easily and fragments can become established elsewhere	No
Resprouts readily when cut, grazed, or burned	Yes
Total points:	5
Total unknowns:	1
Total score:	B? 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
Grasslands, Vernal Pools, Meadows, and other Herb Communities	coastal prairie	D, < 5%
	valley and foothill grassland	D, < 5%
	Great Basin grassland	D, < 5%
	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	D, < 5%
	riparian scrub (incl.desert washes)
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):	D

Infested Jepson Regions

Click here for a map of Jepson regions

CA Floristic Province
Cascade Range
Central West
Great Valley
Northwest
Sierra Nevada
Southwest
Great Basin Province
Modoc Plateau
Sierra Nevada East