Pacific Island Ecosystems at Risk (PIER)


Fraxinus uhdei


RISK ASSESSMENT RESULTS: High risk, score: 11


Australian/New Zealand Weed Risk Assessment adapted for Hawai‘i.
Information on Risk Assessments
Original risk assessment

Fraxinus uhdei (Wenzig) Lingelsh. Family - Oleaceae. Common Name(s) - Mexican ash, shamel ash, tropical ash. Synonym(s) - F. americana L. var. uhdei Wenzig

Answer

Score

1.01

Is the species highly domesticated? (If answer is 'no' then go to question 2.01)

n

0

1.02

Has the species become naturalized where grown?

1.03

Does the species have weedy races?

2.01

Species suited to tropical or subtropical climate(s) (0-low; 1-intermediate; 2-high) – If island is primarily wet habitat, then substitute “wet tropical” for “tropical or subtropical”

2

2.02

Quality of climate match data (0-low; 1-intermediate; 2-high) see appendix 2

2

2.03

Broad climate suitability (environmental versatility)

y

1

2.04

Native or naturalized in regions with tropical or subtropical climates

y

1

2.05

Does the species have a history of repeated introductions outside its natural range? y=-2

y

3.01

Naturalized beyond native range y = 1*multiplier (see Append 2), n= question 2.05

y

2

3.02

Garden/amenity/disturbance weed y = 1*multiplier (see Append 2)

n

0

3.03

Agricultural/forestry/horticultural weed y = 2*multiplier (see Append 2)

n

0

3.04

Environmental weed y = 2*multiplier (see Append 2)

y

4

3.05

Congeneric weed y = 1*multiplier (see Append 2)

y

2

4.01

Produces spines, thorns or burrs

n

0

4.02

Allelopathic

n

0

4.03

Parasitic

n

0

4.04

Unpalatable to grazing animals

n

-1

4.05

Toxic to animals

n

0

4.06

Host for recognized pests and pathogens

y

1

4.07

Causes allergies or is otherwise toxic to humans

n

0

4.08

Creates a fire hazard in natural ecosystems

n

0

4.09

Is a shade tolerant plant at some stage of its life cycle

y

1

4.10

Tolerates a wide range of soil conditions (or limestone conditions if not a volcanic island)

n

0

4.11

Climbing or smothering growth habit

n

0

4.12

Forms dense thickets

y

1

5.01

Aquatic

n

0

5.02

Grass

n

0

5.03

Nitrogen fixing woody plant

n

0

5.04

Geophyte (herbaceous with underground storage organs -- bulbs, corms, or tubers)

n

0

6.01

Evidence of substantial reproductive failure in native habitat

n

0

6.02

Produces viable seed.

y

1

6.03

Hybridizes naturally

6.04

Self-compatible or apomictic

n

-1

6.05

Requires specialist pollinators

n

0

6.06

Reproduction by vegetative fragmentation

n

-1

6.07

Minimum generative time (years) 1 year = 1, 2 or 3 years = 0, 4+ years = -1

 

7.01

Propagules likely to be dispersed unintentionally (plants growing in heavily trafficked areas)

n

-1

7.02

Propagules dispersed intentionally by people

y

1

7.03

Propagules likely to disperse as a produce contaminant

n

-1

7.04

Propagules adapted to wind dispersal

y

1

7.05

Propagules water dispersed

y

1

7.06

Propagules bird dispersed

n

-1

7.07

Propagules dispersed by other animals (externally)

n

-1

7.08

Propagules survive passage through the gut

8.01

Prolific seed production (>1000/m2)

8.02

Evidence that a persistent propagule bank is formed (>1 yr)

y

1

8.03

Well controlled by herbicides

y

-1

8.04

Tolerates, or benefits from, mutilation, cultivation, or fire

y

1

8.05

Effective natural enemies present locally (e.g. introduced biocontrol agents)

   

Total score:

11

Supporting data:

Notes

Reference

1.01

no evidence

1.02

1.03

2.01

(1)List of countries with natural populations
Central America: Guatemala
North America: Mexico
List of countries where planted
Asia: Taiwan; India (Uttar Pradesh)
Caribbean: Puerto Rico
Central America: Costa Rica
North America: USA (Arizona; California) Hawaii (2)Native to western and southern Mexico

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://tncweeds.ucdavis.edu/esadocs/documnts/fraxuhd.html

2.02

2.03

(1)Natural latitude range
-Approximate limits north to south: 26N to 14N
Climate descriptors
- Altitude range: 300 - 2600 m
- Mean annual rainfall: 800 - 4000 mm
- Rainfall regime: summer; uniform
- Dry season duration: 4 - 6 months
- Mean annual temperature: 12 - 25C
- Mean maximum temperature of hottest month: 20 - 30C
- Mean minimum temperature of coldest month: 7 - 20C
- Absolute minimum temperature: > -2C (2)Fraxinus uhdei appears to have a rather broad range of tolerance. It has been planted and escaped from plantings in wet and mesic environments. It grows best between 1,000 and 1,700 m elevation but also up to 2,000 m (Smith 1985). Nelson and Schubert (1976) report that it grows best from 450-1500 m in moist, well-drained sites. In mesic and dry areas, it is usually confined to gulches and wet areas (Skolmen, pers. comm., 1991).

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://tncweeds.ucdavis.edu/esadocs/documnts/fraxuhd.html

2.04

(1)Natural latitude range
Approximate limits north to south: 26N to 14N
List of countries with natural populations
Central America: Guatemala
North America: Mexico
List of countries where planted
Asia: Taiwan; India (Uttar Pradesh)
Caribbean: Puerto Rico
Central America: Costa Rica
North America: USA (Arizona; California) Hawaii

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

2.05

(1)"F. uhdei has been introduced to Hawaii, Puerto Rico and sub-Himalayan regions of India for watershed protection and timber production. It is also a popular street and shade tree in California, Arizona and Mexico. In the Central Valley and Bay Area of California"

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

3.01

(1)"F. uhdei can spread into disturbed forest areas. In Hawaii, invasions have been recorded in the islands of Hawaii, Maui, Molokai and Oahu, and F. uhdei has been included among the most disruptive species to native ecosystems. Invasions are more intense on fertile soils and along streams (Harrington RA, Ewel JJ, Parrotta JA (ed), Turnbull JW, 1997. Invasibility of tree plantations by native and non-indigenous plant species in Hawaii. Special issue: Catalysing native forest regeneration of degraded tropical lands. Selected edited papers based on the proceedings of an international symposium and workshop held in Washington, D.C., June 11-14, 1996. Forest-Ecology-and-Management. 1997, 99: 1-2, 153-162; 28 ref.)."

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

3.02

no evidence

3.03

no evidence

3.04

(1) "F. uhdei can spread into disturbed forest areas. In Hawaii, invasions have been recorded in the islands of Hawaii, Maui, Molokai and Oahu, and F. uhdei has been included among the most disruptive species to native ecosystems (Smith, personal opinion). Invasions are more intense on fertile soils and along streams (Harrington RA, Ewel JJ, Parrotta JA (ed), Turnbull JW, 1997. Invasibility of tree plantations by native and non-indigenous plant species in Hawaii. Special issue: Catalysing native forest regeneration of degraded tropical lands. Selected edited papers based on the proceedings of an international symposium and workshop held in Washington, D.C., June 11-14, 1996. Forest-Ecology-and-Management. 1997, 99: 1-2, 153-162; 28 ref.)." (2) The most abundant understorey species under Fraxinus were Cibotium glaucum and Metrosideros polymorpha , dominant components of native Hawaiian rain forest. In contrast, the most abundant understorey species in the Eucalyptus plantations was the alien tree, Psidium cattleianum , and the understorey of Flindersia was dominated by its own offspring.[comparison of vegetation in plantations, suggests F. uhdei can support native plants much better than other plantations] (3)Over 700,000 trees were
planted, all apparently from the same seed source, two trees on Oahu planted in the 1890's (Little and Skolmen 1989). [Although the Nature Conservancy has control effort in place within its reserves, this tree was planted in HUGE numbers in Hawaii, and removing these planted trees is a large part of the challenge. It is unclear whether this species would be a problem today if it had only been used as a street tree, as opposed to planting hundreds of thousands in native forests of Hawaii. Not reported as a problem species outside of Hawaii] (4)In submontane to montane rain forests, the invasive tree species F. uhdei (Mauna Kea Volcano) and M. faya (Kilauea Volcano) have reached heights of 33 3 m and 17 2 m, respectively (Fig. 8 and Materials and Methods in the SI Appendix). Vertical profiles accumulated over 312 ha of individual tree canopies indicated that F. uhdei and M. faya maintain 32–51% greater biomass volume in the upper canopy than do native species (Fig. 3 a and b), decreasing available light to the understory (Table 4 in the SI Appendix), resulting in almost no species at lower levels in the forest (Table 1). Field measurements guided by the remotely sensed data confirmed that only 2–4% of incoming light penetrates the canopies of mature F. uhdei or M. faya vs. 9–13% light penetration in adjacent native forests (Table 4 in the SI Appendix). We also identified the midcanopy species potentially missing from invaded sites, which included native tree ferns (e.g., Cibotium glaucum) and smaller native woody species such as Cheirodendron trigynum and Ilex anomala. The understory of these invaded forests contained few native ground-covering ferns such as Dicranopteris linearis or
native seedlings, as were usually present in their native counterpart forests (20). In sum, these tall, high-leaf-volume invaders create a biologically impoverished environment beneath their canopies [IN CONTRAST to the previous reference, this paper indicates that stands of Fraxinus alter understory light levels to such a degree as to alter ecosystem function & prevent reestablishment of native species] (5)Fraxinus has invaded native forest between spurs of the plantation at these elevations and is spreading downslope along in unpaved road...Our results demonstrate that the introduction of Fraxinus uhdeii to a montane tropical forest in Hawaii has produced marked changes in the ecosystem processes of decomposition and nutrient cycling. As hypothesized, Fraxinus uhdei, a fastgrowing, nutrient-demanding exotic tree, produced more litter, of higher quality, than the native dominant Metrosideros. Fraxinus litter had higher nutrient concentrations and lower concentrations of lignin and soluble polyphenols. Further, microorganisms colonizing both litter types appear to experience Fraxinus litter as being of higher quality as indicated by their allocation of resources to enzyme production...The marked differences in litter chemistry and microbial activity between litter types resulted in Fraxinus litter decomposing and releasing nutrients at nearly twice the rate of Metrosideros litter. [Propagule pressure and proximity to native forests has facilitated invasion, which has altered ecosystem function].

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2) Harrington, R. A.; Ewel, J. J.1997. Invasibility of tree plantations by native and non-indigenous plant species in Hawaii. Forest Ecology and Management, 99:153-162 (3)http://tncweeds.ucdavis.edu/esadocs/documnts/fraxuhd.html (4)Asner, G. P., R. F. Hughes, P. M. Vitousek, D. E. Knapp, T. Kennedy-Bowdoin, J. Boardman, R. E. Martin, M. Eastwood , and R. O. Green. 2008. Invasive plants transform the three-dimensional structure of rain forests. Proc. Natl. Acad. Sci. USA. Published online on March 3, 2008 (5)D. E. Rothstein, P. M. Vitousek, and B. L. Simmons. 2004. An Exotic Tree Alters Decomposition and Nutrient Cycling in A Hawaiian Montane Forest. Ecosystems 7: 805–814.

3.05

(1)Fraxinus angustifolia and Fraxinus ornus are weeds on unknown importance in Australia (2)Several species of ash are cultivated in New Zealand. F. excelsior can be distinguished by the number of leaflets and green midrib…Competes with native species for space, and shades smaller plants and trees...Which habitats is it likely to invade? : Riverflats, forest, shrubland, scrub and waste places.

(1)Randall, R. 2001. Garden thugs, a national list of invasive and potentially invasive garden plants. Plant Protection Quarterly 16:138-171. (2)http://weedbusters.co.nz/weed_info/detail.asp?WeedID=154 [Accessed 11 Mar 2008]

4.01

(1)"Tree up to 24-(28) m tall, bark gray or brown, furrowed; young branches pubescent, soon glabrate"

(1)Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp.

4.02

no evidence

4.03

no evidence

4.04

unlikely -- several congeners are used as fodder e.g. (1)Fraxinus ornus (2)Fraxinus excelsior

(1)Platis, P.; Papanastasis, V.1993. Productivity of deciduous fodder trees and shrubs in relation to the year of cutting. REUR Technical Series - FAO Regional Office for Europe, , No.28, pp.134-136 (2)Arredondo, S.; Aronson, J.; Ovalle, C.; Pozo, A. del; Avendao, J. 1998. Screening multipurpose legume trees in central Chile. Forest Ecology and Management,109, :221-229

4.05

no evidence

4.06

(1)Siphoninus phillyreae (ash white fly) <http://creatures.ifas.ufl.edu/orn/ash_whitefly.htm>
"Ash whitefly, Siphoninus phillyreae, was described as Aleyrodes phillyreae by Haliday (1835), on Phillyrea latifolia collected in Dublin, Ireland. It has several synonyms listed in Mound and Halsey (1978). In the United States, S. phillyreae was first collected in Los Angeles County, California in 1988, and has since spread to Kern, Orange, Riverside, Sacramento, San Bernardino, San Diego, Santa Barbara, Santa Clara, Stanislaus, Tulare and Ventura counties. Most ash whiteflies in California were found on pomegranate, ash tree, pear, apple, loquat and citrus. It causes severe damage to pear and apple in Europe. Heavy infestations caused leaf wilt, early leaf drop and smaller fruit (Bellows et al. 1990). If this whitefly is introduced into Florida we expect it to become a pest of ornamental plants and possibly other crops. "

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

4.07

no evidence

4.08

no evidence

4.09

(1)" F. uhdei is relatively shade tolerant and can regenerate by coppicing (Walters GA, Wick HL, 1973. Coppicing to convert cull Australian Toon, Tropical Ash to acceptable trees. USDA-Forest-Service-Research-Note,-Pacific-Southwest-Forest-and-Range-Experiment-Station. 1973, No. PSW-283, 4 pp.; 2 ref.). " (2)shade tolerance of seedlings and saplings

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://tncweeds.ucdavis.edu/esadocs/documnts/fraxuhd.html

4.10

Descriptors
- Soil texture: medium
- Soil drainage: free
- Soil reaction: acid; neutral
- Special soil tolerances:

CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

4.11

tree

4.12

(1)forming dense stands from which most native species are excluded [this statement conflicts with Harrington, R. A.; Ewel, J. J.1997. Invasibility of tree plantations by native and non-indigenous plant species in Hawaii. Forest Ecology and Management, 99:153-162 "The most abundant understorey species under Fraxinus were Cibotium glaucum and Metrosideros polymorpha , dominant components of native Hawaiian rain forest." (2)Ash escaped from tree plantations in Kamakou Preserve, is spreading rapidly along water courses, and is forming dense, nearly monotypic stands. [In contrast to Harirington and Ewel, F. uhdei can form monotypic stands that will alter light levels & nutrient decomposition in the understory].

(1)http://www.botany.hawaii.edu/faculty/cw_smith/fra_uhd.htm (2)Holt, R.A. 1992. Control of Alien Plants in Nature Conservancy Preserves. Pp. 525-535 in C.P. Stone, C. W. Smith and J. T. Tunison (eds.). Alien Plant Invasions in Native Ecosystems of Hawai`i: Management and Research. Cooperative National Park Resources Studies Unit University of Hawaii, Manoa.

5.01

terrestrial

5.02

tree; Oleaceae

5.03

Oleaceae

5.04

tree

6.01

(1)"F. uhdei is a fast-growing, medium to large tree (up to 35-40 m tall and 1 m stem diameter) that grows naturally in mixed mountain forests from west-central Mexico to Guatemala and can become weedy in disturbed sites. "

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

6.02

(1)p.991"in Hawaii over 700,000 trees planted by state foresters from 1924 1960 on all of main islands except Ni'ihau and Kaho'olawe, the stands extensively reseeding themselves, but apparently only spreading in few locations "

(1)Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp.

6.03

Possibly (1)"May be able to hybridize with and Oregon ash (F. latifolia), which is native to California. In addition, it appears that hybridization is occurring in many other places -- though perhaps more commonly involving escaped populations of F. velutina cv. "Modesto" than pure native material. The situation with the ashes along Spring Brook between Fairmont Park and the Santa Ana River (NW edge of Riverside) is very confusing and I've been of the impression that introgression is happening there. This may involve 3 populations, incl. native velutina and the two sets of escapees."

(1)DiTomaso, J. M., and E. A. Healy. 2007. Weeds of California and Other Western States. University of California Agriculture and Natural Resources Publication 3488. Oakland, CA.

6.04

p.991"Flowers unisexual (and the plant dioecious)"

Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp.

6.05

no evidence, probably wind pollinated

6.06

(1)" Ability to sucker" [but not evidence of spread by vegetative fragmentation] (2)Fraxinus uhdei regenerates mostly or possibly exclusively from seed (Skolmen, pers. comm., 1991)

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International. (2)http://tncweeds.ucdavis.edu/esadocs/documnts/fraxuhd.html

6.07

no evidence

7.01

no evidence

7.02

Planted as ornamental and forestry tree

7.03

no evidence

7.04

(1)p.991"Samaras oblong-elliptic to oblong-oblanceolate, 2-4 cm long, the wing 5-6 mm wide, apex with a small notch"

(1)Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp.

7.05

(1)Ash escaped from tree plantations in Kamakou Preserve, is spreading rapidly along water courses, and is forming dense, nearly monotypic stands [Apparently wind-dispersed seeds are buoyant and capable of spreading along drainages] (2)Can establish in undisturbed riparian areas, but most often in disturbed sites.

(1)Holt, R.A. 1992. Control of Alien Plants in Nature Conservancy Preserves. Pp. 525-535 in C.P. Stone, C. W. Smith and J. T. Tunison (eds.). Alien Plant Invasions in Native Ecosystems of Hawai`i: Management and Research. Cooperative National Park Resources Studies Unit University of Hawaii, Manoa. (2)DiTomaso, J. M., and E. A. Healy. 2007. Weeds of California and Other Western States. University of California Agriculture and Natural Resources Publication 3488. Oakland, CA.

7.06

no evidence

7.07

No means of attachment

7.08

Unknown

8.01

(1)p.991"Samaras oblong-elliptic to oblong-oblanceolate, 2-4 cm long, the wing 5-6 mm wide, apex with a small notch" [reproductive capability of large trees unknown]

(1)Wagner, W.L., D.R. Herbst and S.H. Sohmer. 1990. Manual of the flowing plants of Hawai‘i. Revised edition. University of Hawai‘i Press, Honolulu. 1853pp.

8.02

Seeds banks may survive up to eight years, as suggested by continued seedling recruitment in populations controlled at Hawaii Volcanoes National Park.

http://tncweeds.ucdavis.edu/esadocs/documnts/fraxuhd.html

8.03

(1)Ring notching or cut stump with Garlon 3A is recommended for larger plants. Arakaki et al. (1989) found that undiluted Garlon 3A in a continuous ring notch application offered complete control. Lower concentrations than that recommended for notching may also be effective.

(1)http://tncweeds.ucdavis.edu/esadocs/documnts/fraxuhd.html

8.04

(1)Silvicultural characteristics descriptors
- Tolerates fire; shade
- Ability to sucker; regenerate rapidly; suited for coppicing

(1)CAB International, (2000) Forestry Compendium Global Module. Wallingford, UK: CAB International.

8.05

Unknown


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