Plant Assessment Form

More Myoporum laetum resources

Myoporum laetum

Common Names: ngaio tree; false sandalwood; mousehole tree

Evaluated on: 9/28/04

List committee review date: 11/02/2005

Re-evaluation date:

Evaluator(s)

Peter J. Warner
California Department of Parks and Recreation; CNPS; Cal-IPC
P. O. Box 603, Little River, CA 95456
(707) 937-9172 (w); (707) 937-278 (h)
pwarner@mcn.org

List committee members

Carla Bossard
John Randall
Cynthia Roye
Jake Sigg
Peter Warner

General Comments

No general comments for this species

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

U. Unknown

Reviewed Scientific Publication

Impact?
Four-part score UACD Total Score
B

1.2

?Impact on plant community

A. Severe

Other Published Material

1.3

?Impact on higher trophic levels

C. Minor

Other Published Material

1.4

?Impact on genetic integrity

D. None

Other Published Material

2.1

?Role of anthropogenic and natural disturbance in establishment

B. Moderate

Reviewed Scientific Publication

Invasiveness?
Total Points
14 Total Score B

2.2

?Local rate of spread with no management

B. Increases less rapidly

Observational

2.3

?Recent trend in total area infested within state

C. Stable

Observational

2.4

?Innate reproductive potential
(see Worksheet A)

B. Moderate

Other Published Material

2.5

?Potential for human-caused dispersal

A. High

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 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? 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.	U Reviewed Scientific Publication
Identify ecosystem processes impacted: The species accumulates dead twigs, rendering it flammable (1). However, no documentation that this species has actually contributed to the spread of wildland fires, or to a change in fire intensity or frequency. insuffucient documentation of impact on fire regimes Sources of information:
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.	A Other Published Material
Identify type of impact or alteration: Competition for light, moisture, nutrients in moist habitats, displacing native species of trees, shrubs, herbs, and forming monocultures (1, 2, 3, 4, 5, 6). Personal observations, personal communications about Myoporum populations in California state parks. Sources of information:
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.	C Other Published Material
Identify type of impact or alteration: Potentially toxic to wildlife, based on published accounts of toxicity to livestock, including sheep and cattle (1, 2, 3). Attractiveness of fleshy fruits could contribute to wildlife poisoning, although fruits are less toxic than foliage (2). Foliage is likely to be ingested by some herbivores, such as deer, and fruit is toxic to some degree, potentially injuring birds. Sources of information:
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 Other Published Material
None likely. This is the only species in the family that grows without human assistance in California (1). No closely related species native to California. Sources of information: 1. Hickman, JC (editor). 1993. The Jepson Manual: Higher Plants of California (Third Printing, with corrections). University of California Press, Berkeley. p. 765.
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.	B Observational
Describe role of disturbance: Results of germination trials (1) suggest that Myoporum requires moisture and light for optimal germination rates. Myoporum's 4 seeds/fruit are encased in a hard endocarp; cutting of this endocarp resulted in no difference in germination, suggesting that physical disturbance is not necessarily needed for seed germination. However, germination does not occur if the 4-seeded unit is retained within the fleshy drupe. Reports indicate that this species spreads from landscape plantings into adjacent moist areas, or where the water table may be near to the soil surface (2, 3, 4, 5, 6). Under these conditions, Myoporum appears to need little physical disturbance. In light of these observations, the posted score here is conservative. Sources of information: 1. Burrows, CJ. 1996. Germination behaviour of seeds of the New Zealand woody species Melicope simplex, Myoporum laetum, Myrsine divaricata, and Urtica ferox. New Zealand Journal of Botany 34(2):205-213. 2. Goode, Suzanne. 2004. Personal communication. State Parks Resource Ecologist, Angeles District, California Department of Parks and Recreation. 3. Kerbavaz, Joanne. 2004. Personal communication. State Parks Resource Ecologist, San Mateo Coast Sector, Santa Cruz District, California Department of Parks and Recreation. 4. Orr, Regena. 2004. Personal communication. State Parks Resource Ecologist, San Luis Obispo Coast District, California Department of Parks and Recreation. (805) 771-1913 / rorr@hearst-castle.org 5. Smith, Darren Scott. 2004. Personal communication. State Parks Resource Ecologist,. San Diego Coast District, California Department of Parks and Recreation. (619) 278-3785 6. Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net
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	B Observational
Describe rate of spread: Spreads from landscape plantings at central and southern California coastal state parks, where campground plantings of Myoporum are common. Also observed spreading occasionally from landscape plantings in northern coastal California. No indication or observations that the spread is rampant; a conservative estimation of spread is less than doubling in area over 10 years. Sources of information: 1. Goode, Suzanne. 2004. Personal communication. State Parks Resource Ecologist, Angeles District, California Department of Parks and Recreation. 2. Kerbavaz, Joanne. 2004. Personal communication. State Parks Resource Ecologist, San Mateo Coast Sector, Santa Cruz District, California Department of Parks and Recreation. 3. Orr, Regena. 2004. Personal communication. State Parks Resource Ecologist, San Luis Obispo Coast District, California Department of Parks and Recreation. (805) 771-1913 / rorr@hearst-castle.org 4. Smith, Darren Scott. 2004. Personal communication. State Parks Resource Ecologist,. San Diego Coast District, California Department of Parks and Recreation. (619) 278-3785 5. Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net
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 Observational
Describe trend: No quanified information on total area infested. The species has been planted widely for many years, and is currently being removed in several state parks. A qualified estimate, based on this species' widespread use in landsapes, and the current rate of removal. Sources of information: Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net
Question 2.4 Innate reproductive potential? Assess the innate reproductive potential of this species. Worksheet A is provided for computing the score.	B Other Published Material
Describe key reproductive characteristics: Fruit is a fleshy drupe enclosing a stony endocarp containing 1-4 seeds (1, 2). Seeds removed from fruit and endocarp tend to germinate more readily than those remaining contained in the endocarp (1, 2). The endocarp may be an adaptation for seed longevity, and could account for long-lived seed banks. Abundance of seed production is unclear: > 1000 seeds/square meter? Seeds will definitely germinate in suitable habitat in California. Sources of information: 1. Burrows, CJ. 1996. Germination behaviour of seeds of the New Zealand woody species Melicope simplex, Myoporum laetum, Myrsine divaricata, and Urtica ferox. New Zealand Journal of Botany 34(2):205-213. 2. DiTomaso, J, and E. Healy. (in production). Weeds of California and Other Western States (unpublished).
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 Other Published Material
Identify dispersal mechanisms: Nurseries sell this species, seed catalogues advertise it, and the City of Los Angeles identifies it as a desirable street tree (1). Calif. Dept. of Parks and Recreation and other agences planted this tree widely in coastal areas over the past century Sources of information: 1. City of Los Angeles website. 2004. http://www.lacity.org/BOSS/streettree/MyoporumLaetum.htm
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.	A Other Published Material
Identify dispersal mechanisms: Sources of information:
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 Other Published Material
Identify other regions: Native to New Zealand coastal forests (1, 2). Cited (2) as invasive in Hawai'i, but not by USDA (3) in that state. Otherwise, no reports from anywhere other than the California coast, where it apparently invades habitats other than coastal forests. Due to frost sensitivity, and need for moisture, this species would probably not pose invasive threat to interior California, or the more northern coast - this may account for its scarcity as an invasive plant north of the SF Bay Area. Sources of information:
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 Other Published Material
Central and southern California coast, especially moist to wet habitats, including coastal scrub, riparian woodland and scrub, salt, brackish, and freshwater marshes, dunes/strand where moisture is available (1, 2, 3, 4, 5, 6, 7) Sources of information: 1. Kitz, J. 2000. Myoporum laetum. in Bossard, CC, JM Randall, and MC Hoshovsky. Invasive Plants of Californias Wildlands. University of California Press, Berkeley. pp. 246-249. 2. DiTomaso, J, and E. Healy. (in production). Weeds of California and Other Western States (unpublished). 3. Goode, Suzanne. 2004. Personal communication. State Parks Resource Ecologist, Angeles District, California Department of Parks and Recreation. 4. Kerbavaz, Joanne. 2004. Personal communication. State Parks Resource Ecologist, San Mateo Coast Sector, Santa Cruz District, California Department of Parks and Recreation. 5. Orr, Regena. 2004. Personal communication. State Parks Resource Ecologist, San Luis Obispo Coast District, California Department of Parks and Recreation. (805) 771-1913 / rorr@hearst-castle.org 6. Smith, Darren Scott. 2004. Personal communication. State Parks Resource Ecologist,. San Diego Coast District, California Department of Parks and Recreation. (619) 278-3785 7. Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net
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.	C Observational
Describe distribution: more common in these ecological types from SF Bay Area south (1, 2, 3, 4, 5) conservative estimates, lacking any quantified data. Sources of information: 1. Goode, Suzanne. 2004. Personal communication. State Parks Resource Ecologist, Angeles District, California Department of Parks and Recreation. 2. Kerbavaz, Joanne. 2004. Personal communication. State Parks Resource Ecologist, San Mateo Coast Sector, Santa Cruz District, California Department of Parks and Recreation. 3. Orr, Regena. 2004. Personal communication. State Parks Resource Ecologist, San Luis Obispo Coast District, California Department of Parks and Recreation. (805) 771-1913 / rorr@hearst-castle.org 4. Smith, Darren Scott. 2004. Personal communication. State Parks Resource Ecologist,. San Diego Coast District, California Department of Parks and Recreation. (619) 278-3785 5. Warner, PJ. 2004. Personal observations, 1995-2004, Marin, Sonoma, Mendocino Counties. (707) 937-2278/ corylus@earthlink.net

Worksheet A - Innate reproductive potential

Reaches reproductive maturity in 2 years or less	No
Dense infestations produce >1,000 viable seed per square meter	Unknown
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	No
Fragments easily and fragments can become established elsewhere	No
Resprouts readily when cut, grazed, or burned	Yes
Total points:	4
Total unknowns:	2
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:

Fruit is a fleshy drupe enclosing a stony endocarp containing 1-4 seeds. Seeds removed from fruit and endocarp tend to germinate more readily than those remaining contained in the endocarp. The endocarp may be an adaptation for seed longevity, and could account for long-lived seed banks.

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	C, 5% - 20%
	desert
	interior
Scrub and Chaparral	coastal bluff scrub
	coastal scrub	C, 5% - 20%
	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
	Great Basin grassland
	vernal pool
	meadow and seep
	alkali playa
	pebble plain
Bog and Marsh	bog and fen
Bog and Marsh	marsh and swamp	C, 5% - 20%
Riparian and Bottomland habitat	riparian forest
	riparian woodland	D, < 5%
	riparian scrub (incl.desert washes)	D, < 5%
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):	A
	Distribution (highest score):	C

Infested Jepson Regions

Click here for a map of Jepson regions

Central West
Great Valley
Northwest
Sierra Nevada
Southwest
Sierra Nevada East
Mojave Desert

California Invasive Plant Council

Protecting California’s environment and economy from invasive plants

Plant Assessment Form

More Myoporum laetum resources

Myoporum laetum

Evaluator(s)

List committee members

General Comments

Table 2. Criteria, Section, and Overall Scores

Table 3. Documentation

Worksheet A - Innate reproductive potential

Related traits:

Worksheet C - California Ecological Types

Infested Jepson Regions