Plant Assessment Form

Stipa capensis

Synonyms: Achnatum capense

Common Names: Cape ricegrass

Evaluated on: 3/24/05

List committee review date: 08/07/2005

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
Joseph M. DiTomaso
University of California, Davis
Dept. Plant Sci., Mail Stop 4, Davis, CA 95616
530-754-8715
jmditomaso@ucdavis.edu

List commitee members

Jake Sigg
Peter Warner
Bob Case
John Knapp
Elizabeth Brusati

General Comments

Richard Minnich and Andrew Sanders wrote a short review of Stipa capensis for us, the only information we have from California.

Table 2. Criteria, Section, and Overall Scores

Overall Score? Moderate
Alert Status? Alert
Documentation? 2 out of 5
Score Documentation
1.1 ?Impact on abiotic ecosystem processes B Observational
Impact?
Four-part score BBCU Total Score
B
1.2 ?Impact on plant community B. Moderate Observational
1.3 ?Impact on higher trophic levels C. Minor Observational
1.4 ?Impact on genetic integrity U. Unknown
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Observational
Invasiveness?
Total Points
12 Total Score B
2.2 ?Local rate of spread with no management A. Increases rapidly Other Published Material
2.3 ?Recent trend in total area infested within state B. Increasing less rapidly Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
C. Low Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal C. Low Anecdotal
2.6 ? Potential for natural long-distance dispersal B. Occasional Other Published Material
2.7 ?Other regions invaded C. Already invaded Observational
3.1 ?Ecological amplitude/Range
(see Worksheet C)
D. Narrow Observational
Distribution?
Total Score D
3.2 ?Distribution/Peak frequency
(see Worksheet C)
D. Very low Anecdotal

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? B Observational
Identify ecosystem processes impacted:

Increased fire danger. In the future, Stipa capensis may present an enormous fire hazard to desert ecosystems, possibly a greater threat than Bromus rubens. In 2001 during protracted drought, a fire carried largely by a solid sheet of S. capensis spread over 400 ha of the north-facing slope adjoining Chino Canyon. This trend is alarming because it appears that S. capensis can survive drought better than Bromus rubens, the primary invasive fuel responsible for fires in California deserts since the late 1970s (1, 2).


Sources of information:

1. Andrew C. Sanders, Herbarium, Department of Botany and Plant Sciences, University of California, Riverside, CA
2. Richard A. Minnich, Department of Earth Sciences, University of California, Riverside, CA


Question 1.2 Impact on plant community composition,
structure, and interactions?
B Observational
Identify type of impact or alteration:

Reduces native wildflower abundance. The desert wildflower season in southern California in 2005 is possibly the best living memory. Most areas are dominated by native forbs in suffcient abundance to make color on hillslopes at a distance. However, at Chino Canyon the dense stands of S. Capensis had few native wildflowers.


Sources of information:

1. Andrew C. Sanders, Herbarium, Department of Botany and Plant Sciences, University of California, Riverside, CA
2. Richard A. Minnich, Department of Earth Sciences, University of California, Riverside, CA


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

Conversion of scrub to grass must have an effect on wildlife, although no formal studies have been conducted.


Sources of information:

Jake Sigg and Bob Case, California Native Plant Society, pers. obs.
John Knapp, Catalina Island Conservancy, Pers. obs.


Question 1.4 Impact on genetic integrity? U

Sources of information:

Hickman, J. C. (ed.) 1993. The Jepson Manual, Higher Plants of California. University of California Press. Berkeley, CA enter text here


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

Seems to prefer a disturbance, but can move into undisturbed desert communities.


Sources of information:

Minnich and Sanders, observational


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

Based on information in Chino Hills.


Sources of information:

Richard Minnich and Andy Sanders, observational.


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

Stipa capensis was discovered in California by Andrew Sanders in 1995 (March 11) at Chino Canyon at 985 feet elevation below the Palm Springs Aerial Tramway (first collection in the United States). It has since expanded across the northern Coachella Valley near Palm Springs. It was collected in 1997 at Cathedral City, at the border with Rancho Mirage (Sanders, March 11) and south of Chino Canyon at 1150 feet (Sanders, March 18). It was collected again at Chino Canyon at 1200 feet (April 15, 2000) and in Cathedral Canyon at 500 feet (April 2 2003) (1). In 2005, Minnich observed extensive cover of S. capensis 10-30 cm tall on the Chino Canyon alluvial fan and on an adjacent north-facing slope at the base of the San Jacinto Mountain below 1200 feet (2).


Sources of information:

1. Andrew C. Sanders, Herbarium, Department of Botany and Plant Sciences, University of California, Riverside, CA
2. Richard A. Minnich, Department of Earth Sciences, University of California, Riverside, CA


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

Annual grass. Germination is usually after the first rains in October or November, and flowering begins in March or April. The spear-like grain is armed with a sharp callus and a long spiral awn, which assist soil penetration following wind dispersal of the seeds (Kadman 1990). Like most annuals, S. capensis also invests most photosynthate into reproduction rather than foliar growth. Aronson et al. (1990) found Desert populations of S. capensis exhibited greater reproductive effort (ratio of diaspores to vegetative biomass) than populations in mediterranean scrub.
Stipa capensis abundance is influenced by shrubs, similar to that in California deserts. Sarig et al. (1994) found that the canopy of scattered perennial shrubs in desert regions may support the growth of annual herbaceous grasses. However, in halophyte environments the high amounts of salt deteriorates the beneficial environment. The production of Stipa capensis, under the canopy of H. scoparia exceeded the amount it produced in the open interspace.


Sources of information:

Kadmon, R.; Shmida, A. 1990. Spatiotemporal demographic processes in plant populations, an approach and a case study. American Naturalist. 135(3) 382-397.
Aronson, J.A., J. Kigel, and A. Shmida. Comparative plant sizes and reproductive strategies in desert and Mediterranean populations of ephemeral plants. Israel Journal of Botany Basic & Applied Sciences 39: 413-430.
Sarig, S., B. Barness, and Y. Steinberger. Annual plant growth and soil characteristics under desert halophyte canopy. Acta Oecologica 15: 521-527.


Question 2.5 Potential for human-caused dispersal? C Anecdotal
Identify dispersal mechanisms:

Not sold much in the nursery industry. Not much opportunity to move through human means, except to be stuck on equipment and clothing.


Sources of information:

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

Fruit designed to be dispersed by attaching to the fur of animals.It appears to have been introduced with cattle from South America.


Sources of information:

DiTomaso and Healy. 2006. Weeds of California. UC DANR Publ. #3488.


Question 2.7 Other regions invaded? C Observational
Identify other regions:

Native to desert and semidesert areas of the mideast and North Africa. Seems to inhabit generally the same areas in California (see 3.1).


Sources of information:

1. Kadmon, R.; Shmida, A. 1990. Spatiotemporal demographic processes in plant populations, an approach and a case study. American Naturalist. 135(3) 382-397.


Section 3: Distribution
Question 3.1 Ecological amplitude/Range? D Observational

Inhabits desert and semi-desert areas. Might have been introduced to California with cattle or tourism, but this is not known. Stipa capensis was discovered in California by Andrew Sanders in 1995 (March 11) at Chino Canyon at 985 feet elevation below the Palm Springs Aerial Tramway (first collection in the United States). It has since expanded across the northern Coachella Valley near Palm Springs. It was collected in 1997 at Cathedral City, at the border with Rancho Mirage (Sanders, March 11) and south of Chino Canyon at 1150 feet (Sanders, March 18). It was collected again at Chino Canyon at 1200 feet (April 15, 2000) and in Cathedral Canyon at 500 feet (April 2 2003) (1). In 2005, Minnich observed extensive cover of S. capensis 10-30 cm tall on the Chino Canyon alluvial fan and on an adjacent north-facing slope at the base of the San Jacinto Mountain below 1200 feet (2).


Sources of information:

1. Andrew C. Sanders, Herbarium, Department of Botany and Plant Sciences, University of California, Riverside, CA
2. Richard A. Minnich, Department of Earth Sciences, University of California, Riverside, CA


Question 3.2 Distribution/Peak frequency? D Anecdotal
Describe distribution:

No widely distributed as of yet.


Sources of information:

Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less Yes
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 Unknown
Viable seed produced with both self-pollination and cross-pollination Unknown
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: 2
Total unknowns: 2
Total score: C?

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 scrubD, < 5%
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 Communitiescoastal prairie
valley and foothill grassland
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 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): D
Distribution (highest score): D

Infested Jepson Regions

Click here for a map of Jepson regions

  • Desert Province
  • Mojave Desert
  • Sonoran Desert