Plant Assessment Form

Arundo donax

Common Names: giant reed

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 AAAD Total Score
A
1.2 ?Impact on plant community A. Severe Other Published Material
1.3 ?Impact on higher trophic levels A. Severe Reviewed Scientific Publication
1.4 ?Impact on genetic integrity D. None
2.1 ?Role of anthropogenic and natural disturbance in establishment B. Moderate Other Published Material
Invasiveness?
Total Points
15 Total Score B
2.2 ?Local rate of spread with no management B. Increases less rapidly Other Published Material
2.3 ?Recent trend in total area infested within state A. Increasing rapidly Observational
2.4 ?Innate reproductive potential
(see Worksheet A)
B. Moderate Reviewed Scientific Publication
2.5 ?Potential for human-caused dispersal B. Moderate Other Published Material
2.6 ? Potential for natural long-distance dispersal A. Frequent 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 A
3.2 ?Distribution/Peak frequency
(see Worksheet C)
B. Moderate 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? A Reviewed Scientific Publication
Identify ecosystem processes impacted:

High water use and light suppression of competing species. Water temperature increase due to reduced shading typical of native trees. Can form near monotypic stands.


Sources of information:

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

Displaces native vegetation, shades out lower level plant species. Has been show to comprise 68% of riparian vegetation in Santa Ana River. Other observations indicate nearly pure monotypic stands.


Sources of information:

Question 1.3 Impact on higher trophic levels? A Reviewed Scientific Publication
Identify type of impact or alteration:

Sources of information:

Question 1.4 Impact on genetic integrity? D

none Does not reproduce sexually.


Sources of information:

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

Can establish with or without disturbance. New infestation can develop downstream in undisturbed habitat from fragmentation of upstream populations.


Sources of information:

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

Locally slow because of lack of seed production, particularly in areas where plants are not subject to flooding and fragmentation of rhizomes or stems. Rapid spread can occur periodically with flooding events that wash away plant fragments.


Sources of information:

Hoshovsky, M. 1986. Arundo donax. The Nature Conservancy Elements of Stewardship Abstract. Tncweeds.ucdaivs.edu/esadocs/arundona.html; also much observational data (T. Dudley, C. Bossard, J. DiTomaso, etc.)


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

Because of periodic flooding events or mechanical damage, overall trend in Arundo donax is observationally considered to be rapid, greater than doubling every 10 years. El Nino year caused tremendous flooding throughout the state and dramatic increases in Arundo populations in new locations and in already infested areas. Due to fragmentation of stems and rhizomes.


Sources of information:

Observational data from many sources (DiTomaso, Rafferty, Team Arundo, etc.)


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

No sexual reproduction, rapid spread with fragmentation of plant parts above and below ground. Rapid spread despite lack of seed production.


Sources of information:

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

Plants sold in the nursery industry today, but more often in the past. Mechanical damage caused to humans can lead to long distance transport in water to new sites. Many problematic populations are close to urban area and water sources, where escapes appear to be from cultivated plants.


Sources of information:

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

Water is the main pathway of movement of Arundo donax following fragmentation. Flooding or mechanically damaged plants cause fragments to enter the water where they can be transported long distances.


Sources of information:

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

Giant reed is naturalized and invasive in many regions, including southern Africa, subtropical United States through Mexico, the Caribbean islands and South America, Pacific Islands, Australia, and Southeast Asia (Hafliger and Scholz 1981). Used and transported around the world for years.


Sources of information:

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

Giant reed was brought to North America quite early, as it was abundant by 1820 in the Los Angeles River, where it was harvested for roofing material and fodder.


Sources of information:

Dudley, T. 2000. Arundo donax. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, and M. Hoshovsky. UC Press, Berkeley; Hoshovsky, M. 1986. Arundo donax. The Nature Conservancy Elements of Stewardship Abstract. Tncweeds.ucdaivs.edu/esadocs/arundona.html


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

Primarily found in Riparian areas and in freshwater aquatic systems. Can also be found in meadows and seeps, as well as marshes and swamps. Most common in scrub and woodland riparian areas and along rivers, streams and canals where primarily observational information indicates that it is present in between 20-50% of these systems.


Sources of information:

Dudley, T. 2000. Arundo donax. In, Invasive Plants of Californias Wildlands. Eds., C. Bossard, J. Randall, and M. Hoshovsky. UC Press, Berkeley; also much observational information including DiTomaso, Warner, Brooks, Dudley, etc.


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. No
Seed production sustained over 3 or more months within a population annually No
Seeds remain viable in soil for three or more years No
Viable seed produced with both self-pollination and cross-pollination No
Has quickly spreading vegetative structures (rhizomes, roots, etc.) that may root at nodes Yes
Fragments easily and fragments can become established elsewhere Yes
Resprouts readily when cut, grazed, or burned Yes
Total points: 5
Total unknowns: 0
Total score: B?

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, reservoirsC, 5% - 20%
Aquatic Systemsrivers, streams, canalsB, 20% - 50%
estuariesD, < 5%
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
chaparral
Grasslands, Vernal Pools, Meadows, and other Herb Communitiescoastal prairie
valley and foothill grassland
Great Basin grassland
vernal poolD, < 5%
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)D, < 5%
Woodlandcismontane woodlandD, < 5%
piñon and juniper woodlandB, 20% - 50%
Sonoran thorn woodlandB, 20% - 50%
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): A
Distribution (highest score): B

Infested Jepson Regions

Click here for a map of Jepson regions

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