Ailanthus altissima - (P. Mill.) Swingle
Other Common Names: tree of heaven
Taxonomic Status: Accepted
Related ITIS Name(s): Ailanthus altissima (P. Mill.) Swingle (TSN 28827)
Unique Identifier: ELEMENT_GLOBAL.2.148863
Element Code: PDSIM01010
Informal Taxonomy: Plants, Vascular - Flowering Plants - Other flowering plants
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Sapindales Simaroubaceae Ailanthus
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Concept Reference
Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Ailanthus altissima
Taxonomic Comments: Called Ailanthus glandulosa in older literature.
Conservation Status

NatureServe Status

Global Status: GNR
Global Status Last Reviewed: 22Mar1994
Global Status Last Changed: 22Mar1994
Rounded Global Status: GNR - Not Yet Ranked
Reasons: Native to central China and widely planted, it now occurs in practically every state of the United States, and from Canada to Argentina, and is also escaped in Europe. Distribution and abundance in native range not known.
Nation: United States
National Status: NNA
Nation: Canada
National Status: NNA (28Sep2016)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (SNA), Arizona (SNA), Arkansas (SNA), California (SNA), Colorado (SNA), Connecticut (SNA), Delaware (SNA), District of Columbia (SNA), Florida (SNA), Georgia (SNA), Idaho (SNA), Illinois (SNA), Indiana (SNA), Iowa (SNA), Kansas (SNA), Kentucky (SNA), Louisiana (SNA), Maine (SNA), Maryland (SNA), Massachusetts (SNA), Michigan (SNA), Mississippi (SNA), Missouri (SNA), Nebraska (SNA), New Jersey (SNA), New Mexico (SNA), New York (SNA), North Carolina (SNA), Ohio (SNA), Oklahoma (SNA), Pennsylvania (SNA), Rhode Island (SNA), South Carolina (SNA), Tennessee (SNA), Texas (SNA), Utah (SNA), Virginia (SNA), Washington (SNA), West Virginia (SNA), Wisconsin (SNA)
Canada British Columbia (SNA), Ontario (SNA), Quebec (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Range Extent Comments: Native to central China and widely planted, it now occurs in practically every state of the U.S. and from Canada to Argentina, and is also escaped in Europe. Distribution and abundance in native range not known.

The frequency of Ailanthus occurrences increases as one nears the cities. In neglected urban areas, Ailanthus grows "as trees close to buildings, as hedges, or as bushy aggregates along railroad tracks, highway embankments".

Overall Threat Impact Comments: Although only occasionally found in nondisturbed areas (Kowarik 1983), ailanthus is a prolific seed producer, grows rapidly and can successfully compete with the native vegetation. It produces toxins which prevent the establishment of other species (Mergen 1959). The root system is aggressive enough to cause damage to sewers and foundations (Hu 1979).

Ailanthus was not nominated by any specific preserve manager, but is recognized by TNC staff as an important exotic weed. A recent survey (2 March 1985) of CNPS members showed a wide distribution of this tree throughout California. Members of both the Mt. Lassen and Sequoia chapters consider it a major pest at low elevations. There are also reports of it growing in Santa Cruz, Riverside, San Bernardino, Los Angeles and San Diego counties.

Short-term Trend: Increase of >10%
Short-term Trend Comments: Trend in native range in China not known, but the species has become much more abundant globally in the past century.

Other NatureServe Conservation Status Information

Global Range: Native to central China and widely planted, it now occurs in practically every state of the U.S. and from Canada to Argentina, and is also escaped in Europe. Distribution and abundance in native range not known.

The frequency of Ailanthus occurrences increases as one nears the cities. In neglected urban areas, Ailanthus grows "as trees close to buildings, as hedges, or as bushy aggregates along railroad tracks, highway embankments".

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States ALexotic, ARexotic, AZexotic, CAexotic, COexotic, CTexotic, DCexotic, DEexotic, FLexotic, GAexotic, IAexotic, IDexotic, ILexotic, INexotic, KSexotic, KYexotic, LAexotic, MAexotic, MDexotic, MEexotic, MIexotic, MOexotic, MSexotic, NCexotic, NEexotic, NJexotic, NMexotic, NYexotic, OHexotic, OKexotic, PAexotic, RIexotic, SCexotic, TNexotic, TXexotic, UTexotic, VAexotic, WAexotic, WIexotic, WVexotic
Canada BCexotic, ONexotic, QCexotic

Range Map
No map available.

Ecology & Life History
Basic Description: Deciduous trees in the family Simaroubaceae, native to China.
General Description: Deciduous trees in the family Simaroubaceae, native to China.
Technical Description: The following description of Ailanthus altissima is adapted from Abrams (1951), Robbins et al. (1951), and Munz and Keck (1973).

Deciduous trees, often 5-20 meters tall, with smooth gray bark, which grow rapidly and spread freely underground. Leaves are 3-6 dm long, 11-25 foliolate, odd pinnate and alternate. Leaves have a disagreeable odor when bruised. The lanceolate to oblong acuminate leaflets are 7-18 mm long. They are mostly entire, having 2-4 teeth near the base of each leaflet.

The small greenish flowers, approximately 6-8 mm long, occur in large terminal panicles which are 1-3 dm long. Flowers open in June. The staminate flowers produce a strong odor. The calyx is made of 5 imbricate segments; the 5 petals are 3-4 mm long. The 10 stamens insert at the base of the disk. The ovaries are 2-5 cleft, with flat, one- celled divisions with a solitary ovule in each cell. Fruits are linear or oblong samaras, 3-5 cm long, and somewhat spirally twisted, turning more or less reddish when ripe.

Reproduction Comments: Ailanthus reproduces both sexually and asexually. Asexual reproduction is by vegetative sprouting from stumps or root portions (Hu 1979). Flowering occurs rather late in the spring (June). Ailanthus has the longest winter dormancy of all the trees in its native Chinese habitat (Hu 1979). Precocious flowering is not a rare occurrence in this species and has been observed in seedlings only 6 weeks after germination (Feret 1973).

Seeds ripen in large crowded clusters from September to October of the same year and may persist on the tree through the following winter (Little 1974, Hu 1979). An individual tree can produce 325,000 seeds per year which are easily wind-dispersed (Bory and Clair-Maczulajtys 1980). These seeds average over 30,000 per kilogram. This amount yields up to 6-7000 "usable plants" (Little 1974). Limited testing of ailanthus seeds indicate that they have dormant embryos, and that germination is benefited by stratification on moist sand for 60 days at 41 F (Little 1974).

Seedlings establish themselves rapidly by producing a well formed tap root in less than three months (Adamik and Brauns 1957). In more compacted soils these seedlings put forth long rope-like lateral roots to exploit a greater soil volume (Rabe and Bassuk 1984). Ailanthus grows quickly in full sunlight and averages a meter of growth in height per year for at least the first 4 years (Adamik and Brauns 1957). The trees may grow to 15-20 meters tall but have a rather short lifespan of less than 50 years (Adamik 1955).

Ecology Comments: Although ailanthus is sensitive to frost damage during its early years (Adamik and Brauns 1957), 6-year-old trees have survived winters of -33 centigrades accompanied by high winds (Zelenin 1976). Although Koffer (1895) suggested that ailanthus was unable to withstand the prolonged dry seasons of the Midwest, Dubroca and Bory (1981) commented on the "drought resistance" of the species. Dry soils are probably more suitable for its growth than wet soils (Adamik and Brauns 1957).

Ailanthus does well on very poor soils. Adamik and Brauns (1957) cultivated the species on rather thin topsoil and it "thrives even on stony ground." The tree has been used in revegetating acid mine spoils, tolerating a pH of less than 4.1, soluble salt concentrations up to 0.25 mmhos/cm and phosphorus levels as low as 1.8 ppm (Plass 1975). The tolerance of ailanthus to soil salinity is a disputed point in the literature. Opinions range from "salty soils not suitable for growth" (Adamik and Brauns 1957) to ailanthus "growing well on very saline shell sands (Lavrinenko and Volkov 1973). Intermediate views are expressed by Brogowski et al. (1977), Semoradova and Materna (1982) and Zelenin (1976).

Ailanthus has been planted widely in urban areas because of its ability to tolerate atmospheric pollution. Its ability to adapt to "the dirt and smoke, the dust and drought of cities" was recognized nearly 100 years ago (Sargent 1888). More recently ailanthus has been observed to survive cement dust near cement and lime works (Klincsek 1976); it is moderately resistant to fumes produced by the coke and coal-tar industry (Kozyukina and Obraztsova 1971); its leaves absorb significant amounts of sulfur in areas of high traffic flow (Kim 1975); it can accumulate high levels of mercury in its tissues (Smith 1972); and it is somewhat resistant to ozone exposure (Davis et al. 1978).

Although ailanthus may suffer from root competition by other trees already established in an area (Cozzo 1972), usually it competes successfully with other plants (Cozzo 1972, Hu 1979) and is considered a "dangerous weed" in forest plantations (Magic 1974). A high degree of shade tolerance gives ailanthus a competitive edge over other plant species (Grime 1965). The production of toxic chemicals by ailanthus may also explain the success of this plant. An aqueous extract of ailanthus leaves has been shown to be toxic to 35 species of gymnosperms and 10 species of angiosperms (Mergen 1959). This may be important in limiting natural succession in ailanthus stands. The toxicity levels are highest in the leaves during the early part of the growing season and are maintained at high levels at least until October (Voigt and Mergen 1962).

Terrestrial Habitat(s): Urban/edificarian
Habitat Comments: Ailanthus is native to central China, where its history is as old as the written language of the country (Hu 1979). Little information is available on its ecology in China, although Hu (1979) reviews its cultural importance and value for wood products and medicine.

The species was apparently introduced into America by two different routes. The first route began with Pierre d'Incarville mistaking it for the lacquer tree in China and sending seeds to England around 1751 (Feret and Bryant 1974, Hu 1979). It was then introduced to America by a Philadelphia gardener in 1784 (Hu 1979). Because of its rapid growth and ability to grow in unfavorable conditions with little care, it became a common stock in eastern nurseries by 1840. The second route was through Chinese miners. During the days of the California gold rush, many Chinese miners brought ailanthus seeds with them as they settled in California, probably because of its medicinal and cultural importance to them.

Escaping from cultivation and quickly becoming established on both coasts, ailanthus has expanded its range considerably since its initial introductions. Specimens from the Harvard University Herbarium indicate that it "runs wild from Oregon ... and from Toronto, Canada ... to Argentina ..." (Hu 1979). In some localities ailanthus is so well established that it appears to be a part of the native flora (Little 1974).

In the eastern United States, the frequency of ailanthus occurrences increases as one nears the cities. In neglected urban areas, ailanthus grows "as trees close to buildings, as hedges, or as bushy aggregates along railroad tracks, highway embankments, walls at the ends of bridges and overpasses, or in cracks of sidewalks and along fences" (Hu 1979). Although it is usually found in disturbed areas, it occasionally spreads to undisturbed areas. Kowarik (1983) views human settlements as centers of its distribution and roads as migration routes.

In California ailanthus is widely naturalized in cismontane areas, especially around old dwellings and mining settlements (Munz and Keck 1973). It has become established in Pleasants Valley, Solano and Marin counties, Berkeley, Vacaville, Petaluma, San Andreas, Angel's Camp, Columbia, and in various places in the Sacramento Valley (Robbins et al. 1951).

Economic Attributes
Economic Uses: Folk medicine
Economic Comments: Valued for wood products and medicine
Management Summary
Stewardship Overview: Ailanthus is a fast growing tree, a prolific seed producer, a persistant stump and root sprouter and an aggressive competitor with respect to the surrounding vegetation. It occurs primarily in disturbed areas, though it may invade undisturbed habitats. It was brought into California mainly by the Chinese who came to California during the goldrush in the 1890's, and frequently occurs in abandoned mining sites. Little work has been done on developing biological or chemical control methods. The most effective means of control may be to pull seedlings by hand before the tap root develops.
Species Impacts: Although only occasionally found in nondisturbed areas (Kowarik 1983), Ailanthus is a prolific seed producer, grows rapidly and can successfully compete with the native vegetation. It produces toxins which prevent the establishment of other species (Mergen 1959). The root system is aggressive enough to cause damage to sewers and foundations (Hu 1979).

Ailanthus was not nominated by any specific preserve manager, but is recognized by TNC staff as an important exotic weed. A recent survey (2 March 1985) of CNPS members showed a wide distribution of this tree throughout California. Members of both the Mt. Lassen and Sequoia chapters consider it a major pest at low elevations. There are also reports of it growing in Santa Cruz, Riverside, San Bernardino, Los Angeles and San Diego counties.

Restoration Potential: Recovery potential is unknown.
Management Requirements: Weed control involves three fundamental objectives: prevention, eradication and control.

From a practical viewpoint, methods of weed management are commonly categorized under the following categories: physical, thermal, managerial, biological, and chemical (Watson 1977). Physical methods include both manual and mechanical methods. Thermal methods include both broadcast burning or spot treatment with a flame thrower. Managerial methods include the encouragement of competitive displacement by native plants and prescribed grazing. Biological control is usually interpreted as the introduction of insects or pathogens which are highly selective for a particular weed species. Chemical control includes both broadcast and spot application.

The most desirable approach is that of an integrated pest management plan. This involves the optimum use of all control strategies to control weeds. This approach is generally accepted as the most effective, economical, and environmentally sound long-term pest control strategy (Watson 1977). In cases where more than one control technique is used, the various techniques should be compatible with one another. Broadcast herbicide application, for example, may not work well with certain managerial techniques (i.e., plant competition).

PHYSICAL CONTROL. The two types of physical control methods discussed below, manual and mechanical, produce slash (i.e., cutting debris) that can be disposed of by several techniques. If cut before seeds are produced it may be piled and left for enhancement of wildlife habitat (i.e., cover for small mammals). Debris may be fed through a mechanical chipper and used as mulch during revegetation procedures. Care should be taken to prevent vegetative reproduction from cuttings. Burning the slash piles is also effective in disposing of slash.

MANUAL CONTROL. Manual methods use hand labor to remove undesirable vegetation. These methods are highly selective and permit weeds to be removed without damage to surrounding native vegetation.

Hand Pulling: Ailanthus is probably best controlled by manual removal of young seedlings. Seedlings are best pulled after a rain when the soil is loose. This facilitates removal of the rooting system, which may resprout if left in the ground. After the tap root has developed, this would be extremely difficult. Plants should be pulled as soon as they are large enough to grasp but before they produce seeds.

The Bradley Method is one sensible approach to manual control of weeds (Fuller and Barbe 1985). This method consists of hand weeding selected small areas of infestation in a specific sequence, starting with the best stands of native vegetation (those with the least extent of weed infestation) and working towards those stands with the worst weed infestation. Initially, weeds that occur singly or in small groups should be eliminated from the extreme edges of the infestation. The next areas to work on are those with a ratio of at least two natives to every weed. As the native plant stabilizes in each cleared area, work deeper into the center of the most dense weed patches. This method has great promise on nature reserves with low budgets and with sensitive plant populations. More detailed information is contained in Fuller and Barbe (1985).

Cutting: Manually operated tools such as brush cutters, power saws, axes, machetes, loppers and clippers can be used to cut ailanthus. This is an important step before many other methods are tried, as it removes the above-ground portion of the plant. For thickly growing, multi-stemmed shrubs and trees, access to the base of the plant may not only be difficult but dangerous where footing is uncertain.

Hand Digging: The removal of rootstocks by hand digging is a slow but sure way of destroying weeds which resprout from their roots. The work must be thorough to be effective as every piece of root that breaks off and remains in the soil may produce a new plant. Such a technique is only suitable for small infestations and around trees and shrubs where other methods are not practical.

Girdling: Girdling involves manually cutting away bark and cambial tissues around the trunks of undesirable trees such as ailanthus. This is a relatively inexpensive method and is done with an ordinary ax in the spring when the trees are actively growing. Hardwoods are known to resprout below the girdle unless the cut is treated with herbicides. Although it may be undesirable to leave standing dead trees in an area, this technique has been shown to reduce stump sprouting in live oaks, and may be a useful technique for controlling ailanthus.

MECHANICAL CONTROL. Mechanical methods use mechanized equipment to remove above ground vegetation. These methods are often non-selective in that all vegetation on a treated site is affected. Mechanical control is highly effective at controlling woody vegetation on gentle topography with few site obstacles such as rocks, stumps or logs. Most mechanical equipment is not safe to operate on slopes over 30 percent. It is also of limited use where soils are highly susceptible to compaction or erosion or where excessive soil moisture is present. Site obstacles such as rocks, stumps or logs also reduce efficiency.

Chopping, Cutting or Mowing: Saplings may be trimmed back by tractor-mounted mowers on even ground or by scythes on rough or stony ground. Unwanted vegetation can be removed faster and more economically in these ways than by manual means and with less soil disturbance than with scarification. However, these methods are non-selective weed eradication techniques. They reduce the potential for biological control through plant competition and open up new niches for undesirable vegetation. In addition, wildlife forage is eliminated.

Saplings usually require several cuttings before the underground parts exhaust their reserve food supply. If only a single cutting can be made, the best time is when the plants begin to flower. At this stage the reserve food supply in the roots has been nearly exhausted, and new seeds have not yet been produced. After cutting or chopping with mechanical equipment, ailanthus resprouts from root crowns in greater density if not treated with herbicides.

PRESCRIBED BURNING. A flame thrower or weed burner device can be used as a spot treatment to heat-girdle the lower stems of small trees. This technique has advantages of being less costly than basal and stem herbicide treatments and is suitable for use during wet weather and snow cover. Ailanthus resprouts after heat-girdling (Cozzo 1972).

MANAGERIAL CONTROL. In most cases ailanthus prevents the establishment of other native plants and must be initially removed. Following physical or thermal removal of mature plants, root crowns must be treated to prevent resprouting. Seedlings of native plant species usually cannot establish fast enough to compete with sprout growth from untreated stumps. Ailanthus is shade tolerant, so presumably can and will sprout under other plants.

Prescribed grazing: The continued removal of the tops of seedlings and resprouts by grazing animals prevents seed formation and also gradually weakens the underground parts. Grazing must be continued until the seedbank is eliminated, as the suppressed plants return quickly after livestock is removed and begin to dominate pastures again.

BIOLOGICAL CONTROL. The term "biological control" is used here to refer to the use of insects or pathogens to control weeds. The introduction of exotic natural enemies to control plants is a complex process and must be thoroughly researched before implementation to prevent biological disasters. Such tools are not normally suitable for preserve managers to implement.

Biological control of ailanthus has not been addressed to any extent beyond the anecdotal stage. No susceptibilty of ailanthus to parasites was found or noticed in Austrian nurseries (Adamik and Brauns 1957). French (1972) notes that the zonate leafspot (Cristulariella pyramidalis) causes defoliation of ailanthus in Florida. In India, Atteva fabricella is considered an ailanthus defoliator (Misra 1978) and Italian seedlings, weakened by cold, were weakly parasitized by the fungus Placosphaeria spp. (Magnani 1975).

Please notify the California Field office of The Nature Conservancy of any field observations in which a native insect or pathogen is seen to have detrimental effects on ailanthus. These reports will be used to update this Element Stewardship Abstract. Management techniques which may encourage the spread of species-specific agents may be desirable in controlling ailanthus.

CHEMICAL CONTROL. Methods of chemical control of ailanthus are poorly explored in the literature. Detailed information on herbicides in general is available in such publications as Weed Science Society of America (1983). The Weed Science Society reference gives specific or USDA (1984) information on nomenclature, chemical and physical properties of the pure chemical, use recommendations and precautions, physiological and biochemical behavior, behavior in or on soils and toxological properties for several hundred chemicals. Comprehensive coverage of this information will not be presented in this Element Stewardship Abstract. In applying herbicides it is recommended that a dye be used in the chemical mixture to mark the treated plants and thus minimize waste.

The following discussion highlights herbicide application methods which may be useful in controlling ailanthus. Herbicides may be applied non-selectively (i.e., broadcast applications) or selectively (i.e., spot applications). Both types of applications have advantages and disadvantages and will be discussed separately.

Broadcast Herbicide Application: In general, when using broadcast application methods, plants should be sprayed only when in full leaf. Results are poor prior to full leaf development. The best results have been obtained when plants are in the fruiting stage in late summer or early autumn (Mathews 1960).

Kolarvskij (1967) reports that 2,4-D can stop seedling growth in alianthus, and Sterrett et al. (1971) found that a mixture of 2- chloroethyl phosphoric acid and potassium iodide gives 80-100% defoliation of ailanthus within 3 weeks.

Spot Chemical Methods: Spot chemical methods consist of various techniques for manually applying herbicides to individual plants or small clumps of plants (such as stump resprouts). These methods are highly selective as only specific plants are treated. They are most efficient when the density of stems to be treated is low.

Jones and Stokes Associates (1984) reviewed a variety of spot chemical techniques. The following is an excerpt from this report, listing techniques in order of increasing possibility of herbicide exposure to the environment or to humans in the vicinity of treated plants.

1) Stem injection: Herbicides are injected into wounds or cuts in the stems or trunks of plants to be killed. The herbicide must penetrate to the cambial tissue and be water-soluble to be effective. The chemical is then translocated throughout the tree and can provide good root-kill, and thus prevents resprouting.

2) Cut stump treatment: Herbicides are directly applied to the cambial area around the edges of freshly cut stumps. Application must occur within 5-20 minutes of cutting to ensure effectiveness. McHenry (1985) suggests late spring as the best season to do this. In early spring sap may flow to the surface of the cut and rinse the chemical off. At other times of the year translocation is too poor to adequately distribute the chemical. Applications may be made with backpack sprayers, sprinkling cans, brush and pail, or squeeze bottles. This treatment is effective in killing root systems of sprouting hardwoods. Picloram should not be used for this technique as it is known to "flashback" through root grafts between treated and untreated plants and may damage the untreated individuals.

Tre-Hold, an asphalt based formulation containing 1% NAA ethylester has been used as a sprout retardant on ailanthus with varying degrees of effectiveness (Amchem Products 1967).

3) Basal/Stem sprays: High concentrations of herbicides in oil or other penetrating carriers are applied, using backpack sprayers, to the basal portion of stems to be killed. The oil carrier is necessary for the mixture to penetrate bark and enter the vascular system. This method gives good root kill, especially in the fall when vascular fluids are moving toward the roots. This method may be easier to use with small diameter stems than the two previous techniques.

4) Herbicide pellets: Pelletized or granular herbicides are scattered at the bases of unwanted plants. Subsequent rainfall dissolves the pellets and leaches the herbicide down to the root system. Optimal time for treatment is towards the end of the rainy season to prevent leaching beyond the root zone.

Monitoring Requirements: Monitoring is needed to determine the presence of ailanthus on or near preserves.

Management Programs: Tim Thomas (1985) has removed a small stand of ailanthus in the Santa Monica Mountains National Recreation Area, by pulling up young saplings and is currently monitoring the site to see if it resprouts.

Contact: Tim Thomas, Park Ranger, Santa Monica Mountains National Recreation Area 22900 Ventura Blvd. Woodland Hills, CA 91364, (213) 888-3440.

Management Research Needs: What types of undisturbed habitats does it invade? How do native species respond to ailanthus toxins, and how is recovery potential of an area previously occupied by ailanthus affected by these toxins? What is the chemical make-up of these toxins? What can be used to buffer the effects of the toxins so that understory native seedling growth is encouraged? At what age is the tap root so long that it precludes ailanthus removal by hand?
Population/Occurrence Delineation Not yet assessed
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank)
Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: Medium
Rounded I-Rank: Medium
I-Rank Reasons Summary: A widespread species, this appears to be primarily invasive on disturbed sites with low habitat quality but with some ability to invade higher quality sites. It appears that if infestations are caught early and treated diligently, the species can be eradicated.
Subrank I - Ecological Impact: Medium/Low
Subrank II - Current Distribution/Abundance: High
Subrank III - Trend in Distribution/Abundance: Medium/Low
Subrank IV - Management Difficulty: Medium/Low
I-Rank Review Date: 29Dec2005
Evaluator: Fellows, M.
Native anywhere in the U.S?
Native Range: Central China (Swearingen et al. 2002)

Download "An Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity". (PDF, 1.03MB)
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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: (Kartesz 1999)

S-2. Present in conservation areas or other native species habitat? Yes
Comments: (Swearingen et al. 2002)

Subrank I - Ecological Impact: Medium/Low

1. Impact on Ecosystem Processes and System-wide Parameters:Medium/Low significance
Comments: ability to colonize poor soils (Bossard et al. 2000; Weber 2003); Kitz (pers. comm.) says Ailanthus traps available soil water in severe infestations; Emmerich and others (1998) imply modifications to water & organic matter content of soil

2. Impact on Ecological Community Structure:High/Moderate significance
Comments: produces dense stands (Swearingen et al. 2002) up to 1 acre (Bossard et al. 2000); can kill shrub layer (Kitz pers. comm.)

3. Impact on Ecological Community Composition:High significance
Comments: produces chemicals that kill or prevent other plants (Swearingen et al. 2002); strongly out-competes the community of native species (Kitz pers comm.)

4. Impact on Individual Native Plant or Animal Species:High/Low significance
Comments: strongly out-competes the community of native species (Kitz pers comm.); displaces native plants (Swearingen et al. 2002)

5. Conservation Significance of the Communities and Native Species Threatened:Low significance/Insignificant
Comments: primarily in disturbed sites (Bossard et al. 2000); rarely inhabits high quality areas (Heibert pers. comm.)

Subrank II. Current Distribution and Abundance: High

6. Current Range Size in Nation:High significance
Comments: (Kartesz 1999)

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:High significance
Comments: inferred from TNC (2001) & (Kartesz 1999); potential negative impacts in all but 3 Ecoregions (Randall and Marinelli 1996)

8. Proportion of Nation's Biogeographic Units Invaded:High significance
Comments: at least 50 Ecoregions- inferred from TNC (2001) & Kartesz (1999); Potential in all but 3 Ecoregions (Randall and Marinelli 1996)

9. Diversity of Habitats or Ecological Systems Invaded in Nation:High/Moderate significance
Comments: Kartesz (1999) reports as wetland plant; riparian & naturally disturbed habitats, but mostly in disturbed or semi-natural habitats (Randall and Marinelli 1996); disturbed or semi-natural habitats of woodland, grassland, creek beds (Bossard et al. 2000); grassland, forest gaps, riparian, flood plains, rock outcrops, disturbed places (Weber 2003); oak woodlands (Kitz pers. comm.)

Subrank III. Trend in Distribution and Abundance: Medium/Low

10. Current Trend in Total Range within Nation:Medium significance/Insignificant
Comments: probably increasing given lack of enemies (Kitz pers. comm.); pathogenic fungi in East may be decreasing or slowing spread (Emmerich pers. comm.)

11. Proportion of Potential Range Currently Occupied:Medium significance/Insignificant
Comments: commercially available since 1840s, spread throughout US; hardy throughout the US (Gilman and Watson 1993)

12. Long-distance Dispersal Potential within Nation:Moderate significance
Comments: wind-dispersed seeds, but low germination (Bossard et al. 2000)

13. Local Range Expansion or Change in Abundance:High/Low significance
Comments: can resprout and rapidly cover an area after control treatment (Bossard et al. 2000); Scheibel (pers. comm.) suggests a locally rapid spread; but Heibert (pers. comm.) says only moderate; does not spread as rapidly as predicted by seed abundance (Bossard et al. 2000)

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Medium/Low significance
Comments: has been reported to invade natural habitats (Swearingen 2002); Kitz (pers. comm.) says can invade natural habitats without disturbance; this appears to be a rare event though

15. Similar Habitats Invaded Elsewhere:Low significance
Comments: has invaded lots of other places: Australia, Canada, Azores, Southern and Eastern Europe, may have also invaded New Zealand, Africa, Mexico, British Isles - however, no reports from new habitat types (Weber 2003)

16. Reproductive Characteristics:Moderate significance
Comments: prolific seeder (up to 325,000/tree/year); fast growing; vigorous re-sprouting; high seed germination rate (Swearingen et al. 2002); seeds viable 1 year (Bossard et al. 2000); establishment seems low & overall it is not aggressive (Kitz pers comm.); Scheibel suggests a period of dormancy for seeds and aggressive reproducer; can grow anywhere (Gilman and Watson 1993)

Subrank IV. General Management Difficulty: Medium/Low

17. General Management Difficulty:Moderate significance
Comments: requires diligence (abundant seeds, high germination rate, vigorous vegetative reproduction); young seedlings hand pulled; must remove entire root structure; several herbicides available (Swearingen et al. 2002; Heibert pers. comm.); Pannill (pers. comm.) if not enough effort given at outset, could get worse problem

18. Minimum Time Commitment:Low significance
Comments: does not have a persistent seed bank (Bossard et al. 2000); but root resprouts are a problem, monitor at least 1 year after the last root resprout (Bossard et al. 2000); Kitz (pers. comm.) need at least a 3-yr plan; Emmerlich (pers. comm.) at least 2-3 yrs because of ability to resprout and possible dormant seed bank

19. Impacts of Management on Native Species:Medium/Low significance
Comments: native shrubs are often misidentified as Ailanthus (Swearingen et al. 2002)

20. Accessibility of Invaded Areas:Low significance
Comments: Bossard and others (2000) warn to 'watch your step', although areas are disturbed sites, it may be hard to get to roots unless cut first, must revisit several times in the first year; occurs on disturbed sites and riparian areas, may be inaccessible during floods
NatureServe Conservation Status Factors Edition Date: 30Nov1988
NatureServe Conservation Status Factors Author: MARC C. HOSHOVSKY, CAFO (1988)
Management Information Edition Date: 30Nov1988
Management Information Edition Author: MARC C. HOSHOVSKY, CAFO
Element Ecology & Life History Edition Date: 30Nov1988
Element Ecology & Life History Author(s): MARC C. HOSHOVSKY, CAFO

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

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