Plant Assessment Form

Atriplex semibaccata

Synonyms: Atriplex denticulata, Atriplex flagellaris

Common Names: Australian saltbush; berry saltbush; creeping saltbush; scrambing berry saltbush

Evaluated on: 8/6/04

List committee review date: 27/08/2004

Re-evaluation date:

Evaluator(s)

John J. Knapp, Invasive Plant Program Manager
Santa Catalina Island Conservancy
PO Box 2739 Avalon, CA 90704
310.510.1299
knappweed@catalinaisp.com
Brianna Richardson, Project Manager
California Invasive Plant Council
1442-A Walnut St. #462, Berkeley, CA 94709
510.843.3902
brichardson@cal-ipc.org

List commitee members

Joe DiTomaso
John Randall
Cynthia Roye
Alison Stanton
Jake Sigg
Peter Warner.

General Comments

Native origin--Australia.

On Santa Catalina Island, A. semibaccata populations are underestimated because the extent of large populations could not be recorded accurately due to the lack of visibility, which is restricted by other vegetation, flat topography, the species' prostrate habit, and distance in the case of aerial and coastal surveys.

Table 2. Criteria, Section, and Overall Scores

Overall Score? Moderate
Alert Status? No Alert
Documentation? 3 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes C Other Published Material
Impact?
Four-part score CADC Total Score
B
1.2 ?Impact on plant community A. Severe Other Published Material
1.3 ?Impact on higher trophic levels D. Negligible Other Published Material
1.4 ?Impact on genetic integrity C. Minor/Low Other Published Material
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Other Published Material
Invasiveness?
Total Points
12 Total Score B
2.2 ?Local rate of spread with no management C. Stable Other Published Material
2.3 ?Recent trend in total area infested within state C. Stable Other Published Material
2.4 ?Innate reproductive potential
(see Worksheet A)
A. High Other Published Material
2.5 ?Potential for human-caused dispersal B. Moderate Other Published Material
2.6 ? Potential for natural long-distance dispersal B. Occasional 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 B
3.2 ?Distribution/Peak frequency
(see Worksheet C)
C. Low Observational

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? C Other Published Material
Identify ecosystem processes impacted:

Alters fire intensity. Increases local soil moisture and nutrient content by bringing minerals, water, and chemicals to the soil surface. Can be used to revegetate mining sites. May reduce SE levels in soil. Minor alteration of fire, water, and nutrient regimes.


Sources of information:

Question 1.2 Impact on plant community composition,
structure, and interactions?
A Other Published Material
Identify type of impact or alteration:

A ground spreading plant, displaces native plants. One plant can form a mat up to 4 ft in diameter. Has a dramatic effect on island grassland populations. Forms dense stands, reduces native vegetation, creates thick ground cover.


Sources of information:

Question 1.3 Impact on higher trophic levels? D Other Published Material
Identify type of impact or alteration:

Seeds eaten by birds. Flowers used by the pygmy blue butterfly. No negative impacts to higher trophic levels documented in the literature. May cause damage through extirpation of native vegetation used as cover and for food. Could rate a "C."


Sources of information:

Randall, JM and MC Hoshovsky. 2000. Atriplex semibaccata. In, Invasive Plants of California's Wildlands. C. Bossard, J. Randall, M. Hoshovsky (eds.) 59-61. University Press, Los Angeles.
Las Pilitas Nursery website: www.laspilitas.com/butterflies


Question 1.4 Impact on genetic integrity? C Other Published Material

31 closely related California natives, some of which are rare or endangered. A. semibaccata can possibly hybridize with two Santa Catalina Island native slabush species (A. coulterie [listed as G2 by NatureServe] and A. pacifica [listed as G3 by NatureServe]). 46 native taxa are in the genus Atriplex in California. A. semibaccata hybridizes readily with A. spinibractea in Australia. No information currently exists on whether A. semibaccata is hybridizing with CA natives. Trials are being conducted on Catalina Island to try to produce a hybrid between A. semibaccata and two native spp


Sources of information:

Randall, JM and MC Hoshovsky. 2000. Atriplex semibaccata. In, Invasive Plants of California's Wildlands. C. Bossard, J. Randall, M. Hoshovsky (eds.) 59-61. University Press, Los Angeles.
DiTomaso, J., E. Healy. Weeds of California and Other Western States. Not yet published.
Personal communication: B. Richardson w/ John Knapp. Email 8/10/2004.
Harden, G.J. 1990. Flora of New South Wales volume 1. New South Wales University Press.
Hickman, J.C. (ed.). 1993. The Jepson manual of higher plants of California. Pp. 501-505. University of California Press, Berkeley.


Section 2: Invasiveness
Question 2.1 Role of anthropogenic and natural disturbance
in establishment?
C Other Published Material
Describe role of disturbance:

Prefers areas that have been heavily grazed or disturbed. Readily establishes in areas newly developed, roadsides, margins of cultivated fields, coastal marshes. Most establishment attributed to disturbance.


Sources of information:

Randall, JM and MC Hoshovsky. 2000. Atriplex semibaccata. In, Invasive Plants of California's Wildlands. C. Bossard, J. Randall, M. Hoshovsky (eds.) 59-61. University Press, Los Angeles.
Harden, G.J. 1990. Flora of New South Wales volume 1. New South Wales University Press.
Wilken, D. and Hannah, L. 1998. Channel Islands National Park Species Literature Review. Unpublished.


Question 2.2 Local rate of spread with no management? C Other Published Material
Describe rate of spread:

Naturalized in localzed areas on Santa Catalina Island prior to 1921. Naturalzed widely by 1966 and 2003. Spread by seed and vegetatively is slow. A large amount of unifested habitat exists on Catalina Island.


Sources of information:

Millspaugh, C.F. and Nuttall, L.W. 1923. Flora of Santa Catalina Island. Pp. 91-92. Field Museum of Natural History, Botany v.5. Chicago.
Thorne, R.F. 1967. A flora of Santa Catalina Island, California. Aliso, 6(3):1-77.
Knapp, J.J. 2003. Prioritized invasive plant management for the Santa Catalina Island Conservancy. Unpublished.
USDA. No Date. Conservation plant characteristics for: Australian saltbush. USDA Natural Resources Conservation Service.
Observational, Peter Warner, Joe DiTomaso, 2004


Question 2.3 Recent trend in total area infested within state? C Other Published Material
Describe trend:

Species not targeted for removal on Catalina as of 2003 (1). Occupies 53,559,275 square ft. on Santa Catalina Island (2). Common on Anacapa Island and in a wide range of habitats on other Northern Channel Islands such as grasslands and disturbed habitats (3). Elkhorn Slough National Estuarine Research Reserve (4). Inland Empire California State Parks (5). A. semibaccata is too widespread for control measures.


Sources of information:

Question 2.4 Innate reproductive potential? A Other Published Material
Describe key reproductive characteristics:

Reproduces by seed only. Flowers April-December. Seeds produced summer-December. Likely self-pollinating (other Atriplex are). Seeds produced in "large numbers," though others state low seed abundance. Seed persistance in soil is unknown. Resprouts when cut. Produces seed annually on Catalina Island. 6 points.


Sources of information:

Randall, JM and MC Hoshovsky. 2000. Atriplex semibaccata. In, Invasive Plants of California's Wildlands. C. Bossard, J. Randall, M. Hoshovsky (eds.) 59-61. University Press, Los Angeles.
Elkhorn Slough National Estuarine Research Reserve. 2000. Weed control by species. Elkhorn Slough National Estuarine Research Reserve. Pp. 1-57.
Wilken, D. and Hannah, L. 1998. Channel Islands National Park Species Literature Review.
Randall, J.M. and Hoshovsky, M.C. 2000. Atriplex semibaccata. In, Invasive Plants of California's Wildlands. (eds.) C. Bossard, J. Randall, and M. Hoshovsky. Pp. 59-61. University Press, Los Angeles.
Knapp, J.J. 2004. Prioritized invasive plant management plan for the Santa Catalina Conservancy. Unpublished.
USDA. No Date. Conservation plant characteristics for: Australian saltbush. USDA Natural Resources Conservation Service.


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

Was promoted as livestock forage, as a ground cover, for erosion control, and to attract birds. Recently promoted as a fire-rsistant ground cover and for reclamation of mined sites in the southwest. Seeds dispersed by human activities. Disposal of soil from urban areas to the Interior may transport seed to new locales. Sold horticulturally. Currently sold horticulturally and for revegetation. Readily moved by soil transport.


Sources of information:

Randall, JM and MC Hoshovsky. 2000. Atriplex semibaccata. In, Invasive Plants of California's Wildlands. C. Bossard, J. Randall, M. Hoshovsky (eds.) 59-61. University Press, Los Angeles.
DiTomaso, J., E. Healy. Weeds of California and Other Western States. Not yet published.
de Villiers, AJ, MW van Rooyen, GK Theron, AS Claassens. 1996. Tolerance of six Namaqualand pioneer species ot saline soil conditions. South African Journal of Plant and Soil 14(1): 38-42.
Las Pilitas Nursery website: www.laspilitas.com/butterflies
Wilken, D. and L. Hannah. 1998. Channel Islands National Park Species Literature Review.
Knapp, JJ. Personal observations from 2001-2004 on Santa Catalina Island, CA. 310.510.1299.
Observational, Peter Warner, Joe DiTomaso, 2004.


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

Fruits are dispersed by frugivores: mammals, birds, reptiles, and ants. Seeds dispersed by water, in mud or soil movement, and animals. Fleshy bright red fruits make them attractive to vectors, and have been found as a dietary constitute of several fauna, which can disperse the seeds over long distances.


Sources of information:

Randall, JM and MC Hoshovsky. 2000. Atriplex semibaccata. In, Invasive Plants of California's Wildlands. C. Bossard, J. Randall, M. Hoshovsky (eds.) 59-61. University Press, Los Angeles.
DiTomaso, J., E. Healy. Weeds of California and Other Western States. Not yet published.
Wilken, D. and L. Hannah. 1998. Channel Islands National Park Species Literature Review.
Observational, Peter Warner, Joe DiTomaso, 2004.


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

Found in NV, AZ, NM, UT, TX. Introduced to South Africa, Chile, Tasmania, Hawaii, Canary Island, South America, central Asia. Similar habitats to those invaded in CA.


Sources of information:

DiTomaso, J., E. Healy. Weeds of California and Other Western States. Not yet published.
Wilken, D, L. Hannah. 1998. Atriplex semibaccata R. Br. (Chenopodiaceae) Australian saltbush, creeping saltbush. Santa Barbara Botanic Garden.
de Villiers, AJ, MW van Rooyen, GK Theron, AS Claassens. 1996. Tolerance of six Namaqualand pioneer species ot saline soil conditions. South African Journal of Plant and Soil 14(1): 38-42.
Wilken, D. and L. Hannah. 1998. Channel Islands National Park Species Literature Review.


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

Introduced to CA as livestock forage, Tulare Co in 1910. Found in margins of grassland, scrub, shrubland, and salt marshes, waste places, and woodland below 3,280 ft. Found in the Mojave and Sonoran deserts, and arid parts of the South Coast, Central Coast, SF Bay area, and Central Valley to Glenn Co. Coastal areas and salt marshes from San Diego to Mendocino Co, as well as all Channel Islands. Common in grasslands on Santa Cruz Island. On Santa Catalina Island, 3308 populations were recorded and the following is the percentage of habitat type invaded: bare soil-2.8%, beach-3.1%, coastal scrub-0.1%, coastal scrub/grassland-6.3%, grassland-0.56%, non-native scrub-0.00%, and riparian-0.17% (2). In 1966, coastal bluff scrub was also invaded on Santa Catalina Island (3). Also found in coastal marsh (4). Considered a regional noxious weed by CDFA. Found in at least 6 major and 11 minor ecotypes in CA.


Sources of information:

Randall, JM and MC Hoshovsky. 2000. Atriplex semibaccata. In, Invasive Plants of California's Wildlands. C. Bossard, J. Randall, M. Hoshovsky (eds.) 59-61. University Press, Los Angeles.
DiTomaso, J., E. Healy. Weeds of California and Other Western States. Not yet published.
Millspaugh, C.F. and Nuttall, L.W. 1923. Flora of Santa Catalina Island. Pp. 91-92. Field Museum of Natural History, Botany v.5. Chicago.
Knapp, J.J. 2004. Prioritzed invasive plant management plan for the Santa Catalina Island Conservancy. Unpublished.
Thorne, R.F. 1967. A flora of Santa Catalina Island, California. Aliso, 6(3):1-77.
Elkhorn Slough National Estuarine Research Reserve. 2000. Weed control by species. Elkhorn Slough National Estuarine Research Reserve. Pp. 1-57.
Wilken, D. and Hannah, L. 1998. Channel Islands National Park Species Literature Review.
Stone, C.P., C.W. Smith, and J.T. Tunison, eds. 1992. Alien plant invasions in native ecosystems of Hawaii: Management and research. University of HawaiI Cooperative National Park Resources Unit, Honolulu, Hawaii.


Question 3.2 Distribution/Peak frequency? C Observational
Describe distribution:

On Catalina Island, ranks a "C." Statewide distribution unknown.


Sources of information:

DiTomaso, J., E. Healy. Weeds of California and Other Western States. Not yet published.
Knapp, JJ. 2004. Prioritized invasive plant management plan for the Santa Catalina Island Conservancy. Unpublished.
Thorne, RF. 1967. A flora of Santa Catalina Island, California. Aliso 6(3): 1-77.
Observational, Peter Warner, Joe DiTomaso, 2004.


Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
Dense infestations produce >1,000 viable seed per square meter Unknown
Populations of this species produce seeds every year. Unknown
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 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 Yes
Total points: 6
Total unknowns: 2
Total score: A?

Related traits:

Seeds produced in "large" numbers.

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
DunescoastalU, Unknown
desert
interior
Scrub and Chaparralcoastal bluff scrubU, Unknown
coastal scrubC, 5% - 20%
Sonoran desert scrubU, Unknown
Mojavean desert scrub (incl. Joshua tree woodland)U, Unknown
Great Basin scrub
chenopod scrub
montane dwarf scrub
Upper Sonoran subshrub scrubU, Unknown
chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairieU, Unknown
valley and foothill grasslandU, Unknown
Great Basin grassland
vernal pool
meadow and seep
alkali playa
pebble plain
Bog and Marshbog and fen
marsh and swampU, Unknown
Riparian and Bottomland habitatriparian forest
riparian woodland
riparian scrub (incl.desert washes)U, Unknown
Woodlandcismontane woodlandU, Unknown
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): D
Distribution (highest score): C

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
  • Desert Province
  • Mojave Desert
  • Sonoran Desert