SPECIES: Acer platanoides
photo courtesy of Pat Breen, Oregon State University
AUTHORSHIP AND CITATION:
Munger, Gregory T. 2003. Acer platanoides. In: Fire Effects Information System, [Online]. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: http://www.fs.fed.us/database/feis/ .
NRCS PLANT CODE :
The currently accepted scientific name for Norway maple is Acer platanoides L. (Aceraceae) [18,45,48,52,63].
Over 100 cultivars of Norway maple have been developed for commercial trade in
North America [10,47].
FEDERAL LEGAL STATUS:
No special status
Norway maple is listed by the state of Vermont as a Category II plant: "Exotic plant species considered to have the potential to displace native plants either on a localized or widespread scale" .
Based on floras and other literature, herbarium samples, and confirmed observations, Norway maple can potentially be found in North America, growing outside cultivation, in the following areas: from New Brunswick and Cape Breton Island west to Minnesota and south to Tennessee and North Carolina. In the West, it is found in British Columbia, Washington, Idaho, and western Montana [8,18,24,34,45,48,52,54,57,63].
Actual distribution of escaped or invasive Norway maple may be more or less broad than the above description. The following description of potential distribution is based on a map developed by Nowak and Rowntree  that describes Norway maple performance when grown as an urban street tree. They describe "optimal range" as areas where Norway maple can be grown with few environmental constraints. Although not confirmed as such, these are areas where it is most likely to escape cultivation and potentially become invasive. The "optimal range" in eastern North America is from southern New England south to Chesapeake Bay, the piedmont of southern Virginia and northern North Carolina, and the Appalachians of western North Carolina, South Carolina, and northern Georgia. This distribution continues west through the northern 1/3 of Alabama and Mississippi and the northern 2/3rds of Arkansas to eastern Oklahoma, then north to southeastern South Dakota and southern Minnesota and Wisconsin. Northern limits of this distribution are delineated by western and northern coastal areas of the Great Lakes and the St. Lawrence River. South of this delineation, inland areas of Maine, eastern Quebec, and the southern Maritimes, as well as northern Vermont/New Hampshire and the Adirondacks, are not included in this distribution .
The "optimal range" in western North America includes western sections of British Columbia, Washington and Oregon, the North Coast and Sierra regions of California, and northern Idaho/northwestern Montana. Nowak and Rowntree  also describe much of the intermountain west and the rest of western and central Montana as "suboptimal range", where some irrigation is required for successful cultivation. Therefore, we might assume that riparian or other mesic habitat is susceptible to invasion in these areas, given a seed source.
There is some indication that Norway maple could be potentially invasive in Canada through climate zone 2b.This includes the Maritime provinces, most of Quebec and Ontario, the southern 2/3rds of Manitoba, Saskatchewan, and Alberta, and all but the coldest areas of British Columbia. However, precise distribution data are lacking .
The following biogeographic classification systems demonstrate where Norway
maple could potentially be found based on the above information. Predicting distribution of
nonnative species is difficult due to gaps in understanding of their
biological and ecological characteristics, and because they may
still be expanding their range. These lists are speculative and may not be
accurately restrictive or complete.
FRES10 White-red-jack pine
FRES13 Loblolly-shortleaf pine
FRES21 Ponderosa pine
FRES22 Western white pine
FRES24 Hemlock-Sitka spruce
FRES26 Lodgepole pine
FRES28 Western hardwoods
Norway maple is not a climax dominant or indicator species in habitat type classifications in North America.
The preceding description provides characteristics of Norway maple that may be relevant to fire ecology and is not meant to be used for identification. Keys for identifying Norway maple are available in various floras (e.g. [18,34,45,48,52,57,63]). Photos and descriptions of Norway maple are also available online at Plants Database, Michigan State University Extension, and Oregon State University websites.
The biology and ecology of Norway maple are not well-studied in North America. More
research is needed to better understand its key biological traits, habitat
requirements and limitations, and interactions with native North American flora
RAUNKIAER  LIFE FORM:
Breeding system: Norway maple is dioecious 
Pollination: Norway maple is insect pollinated .
Seed production: No information
Seed dispersal: Norway maple seeds are wind-dispersed [28,32,55]. Dispersal distance from seed source is enhanced by winged samaras [28,32]. Estimated lateral distance traveled by samaras in a 6.2 miles/hour (10 km/hr) breeze when dropped from a height of "approximately 3/4 of the maximum height of the species" was 165 feet (50.3 m) . Norway maple samaras dry substantially before dispersal and seeds are desiccation-tolerant thereafter . Seeds are dispersed in fall, which provides a high likelihood of protection under winter snow, conditions usually sufficient for stratification .
Seed banking: No information
Germination: Seeds germinate in spring [27,28], following an obligatory period of cold stratification at 37 to 40 degrees Fahrenheit (3-4 °C) for 90-120 days [38,39]. Germination is apparently enhanced by soil disturbance , although exposure to mineral soil is not a prerequisite for germination .
Seedling establishment/growth: Norway maple produces abundant seedlings each spring [28,29]. First true leaves are formed approximately 3 weeks after seedling emergence . A review of European silvicultural literature characterizes Norway maple seedlings as drought tolerant , but other observations indicate that drought resistance of seedlings is low during early development stages . Tolerance to extreme heat or cold is limited during early stages of seedling development. A Russian experiment showed exposure to light frost for 1 hour killed the initial pair of leaves at 28 degrees Fahrenheit (-2 °C) and cotyledons at 25 to 21 degrees Fahrenheit (-4 to -6 °C). Cotyledons and leaves were also killed by exposure to temperatures > 102 degrees Fahrenheit (39 °C) for 2 to 3 hours. Which particular cultivar or variety was used in this experiment is not known . Insulation provided by early-winter snow may reduce seedling damage from cold temperatures .
Information concerning the biology of asexual regeneration in Norway maple is sparse and
conflicting. USDA Natural Resources
Conservation Service Plants Database  indicates that at least one
cultivar of Norway maple (Crimson King) has the ability to "resprout," but none
have "coppice potential." However, Simpfendorfer  lists Norway maple, along
with sugar maple and red maple (A. rubrum), as species that regenerate by "coppicing"
following fire. Postharvest stump sprouting has been documented, although
sprouts originating from saplings and smaller trees are apparently hardier than
those from mature overstory trees . A review of European autecological data categorizes
"tendency to sprouting" for Norway maple as "vigorous" .
As of this writing, there is very little published information describing the ecological range of Norway maple in North America. Because Norway maple is commonly mentioned as a congener of sugar maple in eastern North America [1,25,31,59,60,61,64], and because of their taxonomic similarity, it is likely that the two species share a similar ecological range in this region. (See sugar maple for relevant information.)
In Europe, Norway maple occurs within a climatic range characterized by maximum and minimum growing degree days (accumulated temperatures above 5 °C) of 2600 and 1150, respectively . Within this range, it generally occurs in lowland areas, wide river valleys, and low mountain habitats. Norway maple is usually found as individuals or small groups in European mixed forests, and does not form pure stands over large areas .
Norway maple grows best on moist, "adequately" drained, deep, fertile soils. It is intolerant of low soil nitrogen conditions and is rare on acidic (pH near 4) soils. Norway maple makes "suboptimum" growth on sandy soils or soils high in lime or clay content, and does not tolerate high evapotranspiration or prolonged drought. Conflicting reports assert that it is rare on poorly drained soils, yet it reportedly can tolerate flooding for up to 4 months [36,41].
Northern distribution of Norway maple in North America is probably limited by cold
temperatures. Variation in cold tolerance may be related to genetic source,
since many cultivars of Norway maple have been developed for this trait.
Seedlings can survive temperatures to at least -12 degrees Fahrenheit (-24 °C),
although substantial twig tissue damage can occur. Insulation provided by
early-winter snow may reduce seedling damage from cold temperatures .
Overwintering flower buds may be killed by prolonged exposure to cold temperatures.
In Russia, damage to bud scales and loss of isolated buds have occurred after
exposure for 1 hour at temperatures between 23 and 27 degrees Fahrenheit (-5 to
-3 ºC) and loss of all buds noted below 23 degrees
Fahrenheit (-5º). Open flowers are more sensitive than buds and may be susceptible
to late-season frost. Exposure to temperatures < 27 degrees Fahrenheit (-3 ºC)
for only 15 minutes produced necrosis in the stigma of the style, and 30 minutes
of exposure killed entire flowers .
Norway maple seedlings are characterized as shade tolerant to very shade tolerant. They are often strong competitors in closed-canopy forest understories within the species' North American range [31,60,64]. Seedling growth apparently ceases when light levels fall below 3% of full daylight . Norway maple maintains a continuously recruited "seedling-bank" of persistent, multi-aged seedlings, given a seed source [59,61].
It is likely suppressed Norway maple saplings and seedlings respond favorably following gap formation. In the absence of stand-level disturbance, it is also likely that Norway maple could become a dominant overstory species in eastern deciduous forests where it is established. Along with American beech (Fagus grandifolia) and sugar maple, Norway maple is gradually replacing previously dominant oaks (white oak (Quercus alba), northern red oak (Q. rubra), and black oak (Q. velutina)) in the overstory of a New Jersey piedmont forest [59,60]. Norway maple becomes less shade tolerant with age and mature trees have been characterized as intermediate in shade tolerance . Nevertheless, where it becomes the canopy dominant, Norway maple can suppress regeneration of shade tolerant woody species, including even its own seedlings (see Impacts) .
Webb and others  raise questions concerning whether Norway maple seedlings
are equal to those of sugar maple in persistence, shade tolerance, and response
to release, and point out the importance of these questions in determining competitive
interactions between the two species. Further research is needed to
determine impacts of Norway maple invasion on understory species composition and
potential effects on successional trajectories.
Reproductive buds are formed during summer, overwinter, and open in spring when triggered by warm temperatures . Flowering dates vary geographically, ranging from late April to early June in eastern North America [34,45,48,63]. In Russia, flower buds begin enlargement when temperatures reach 41 to 50 degrees Fahrenheit (5-10 °C). Enlarged buds begin to open when temperatures reach >50 degrees Fahrenheit (10 °C), and fully emerge at between 59 and 68 degrees Fahrenheit (15-20 °C) . Leaves abscise late in autumn (e.g. late October in upper New York) . Norway maple typically sheds its leaves later in the season than most native deciduous species in the northeastern U.S. and adjacent Canada, presumably because the growing season is longer in its native European habitat where it evolved [10,27].
It is unclear to what extent and at what age Norway maple can survive fire by sprouting.
Fire regimes: As of this writing, it is difficult to identify interactions between Norway maple and particular fire regimes in North America because distribution of invasive Norway maple is ill-defined. We can probably assume that Norway maple increases in the absence of fire. It is likely that frequent fires would limit Norway maple establishment.
The following table lists fire return intervals for communities or ecosystems throughout North America where Norway maple may occur. This list is presented as a guideline to illustrate historic fire regimes and is not to be interpreted as a strict description of fire regimes for Norway maple. Find fire further regime information for the plant communities in which this species may occur by entering the species name in the FEIS home page under "Find Fire Regimes".
|Community or Ecosystem||Dominant Species||Fire Return Interval Range (years)|
|silver fir-Douglas-fir||Abies amabilis-Pseudotsuga menziesii var. menziesii||> 200|
|grand fir||Abies grandis||35-200 |
|silver maple-American elm||Acer saccharinum-Ulmus americana||< 35 to 200|
|sugar maple||Acer saccharum||> 1000|
|sugar maple-basswood||Acer saccharum-Tilia americana||> 1000|
|Atlantic white-cedar||Chamaecyparis thyoides||35 to > 200 |
|Arizona cypress||Cupressus arizonica||< 35 to 200 |
|beech-sugar maple||Fagus spp.-Acer saccharum||> 1000|
|black ash||Fraxinus nigra||< 35 to 200 |
|western juniper||Juniperus occidentalis||20-70|
|Rocky Mountain juniper||Juniperus scopulorum||< 35 |
|western larch||Larix occidentalis||25-100 |
|yellow-poplar||Liriodendron tulipifera||< 35 |
|Great Lakes spruce-fir||Picea-Abies spp.||35 to > 200|
|northeastern spruce-fir||Picea-Abies spp.||35-200 |
|southeastern spruce-fir||Picea-Abies spp.||35 to > 200 |
|blue spruce*||Picea pungens||35-200 |
|red spruce*||P. rubens||35-200 |
|pine-cypress forest||Pinus-Cupressus spp.||< 35 to 200 |
|Rocky Mountain lodgepole pine*||Pinus contorta var. latifolia||25-300+ [2,3,46]|
|Sierra lodgepole pine*||Pinus contorta var. murrayana||35-200 |
|shortleaf pine||Pinus echinata||2-15|
|shortleaf pine-oak||Pinus echinata-Quercus spp.||< 10 |
|Jeffrey pine||Pinus jeffreyi||5-30|
|western white pine*||Pinus monticola||50-200|
|Pacific ponderosa pine*||Pinus ponderosa var. ponderosa||1-47 |
|interior ponderosa pine*||Pinus ponderosa var. scopulorum||2-30 [3,6,30]|
|red pine (Great Lakes region)||Pinus resinosa||10-200 (10**) [11,16]|
|red-white-jack pine*||Pinus resinosa-P. strobus-P. banksiana||10-300 [11,21]|
|pitch pine||Pinus rigida||6-25 [9,23]|
|eastern white pine||Pinus strobus||35-200|
|eastern white pine-eastern hemlock||Pinus strobus-Tsuga canadensis||35-200|
|eastern white pine-northern red oak-red maple||Pinus strobus-Quercus rubra-Acer rubrum||35-200|
|loblolly pine||Pinus taeda||3-8|
|loblolly-shortleaf pine||Pinus taeda-P. echinata||10 to < 35|
|Virginia pine||Pinus virginiana||10 to < 35|
|Virginia pine-oak||Pinus virginiana-Quercus spp.||10 to < 35 |
|aspen-birch||Populus tremuloides-Betula papyrifera||35-200 [11,58]|
|quaking aspen (west of the Great Plains)||Populus tremuloides||7-120 [3,20,33]|
|black cherry-sugar maple||Prunus serotina-Acer saccharum||> 1000 |
|Rocky Mountain Douglas-fir*||Pseudotsuga menziesii var. glauca||25-100 [3,4,5]|
|coastal Douglas-fir*||Pseudotsuga menziesii var. menziesii||40-240 [3,35,44]|
|oak-hickory||Quercus-Carya spp.||< 35|
|northeastern oak-pine||Quercus-Pinus spp.||10 to < 35|
|southeastern oak-pine||Quercus-Pinus spp.||< 10|
|white oak-black oak-northern red oak||Quercus alba-Q. velutina-Q. rubra||< 35 |
|canyon live oak||Quercus chrysolepis||<35 to 200|
|blue oak-foothills pine||Quercus douglasii-Pinus sabiniana||<35 |
|northern pin oak||Quercus ellipsoidalis||< 35 |
|Oregon white oak||Quercus garryana||< 35 |
|California black oak||Quercus kelloggii||5-30 |
|chestnut oak||Quercus prinus||3-8|
|northern red oak||Quercus rubra||10 to < 35|
|black oak||Quercus velutina||< 35 |
|redwood||Sequoia sempervirens||5-200 [3,15,53]|
|western redcedar-western hemlock||Thuja plicata-Tsuga heterophylla||> 200 |
|eastern hemlock-yellow birch||Tsuga canadensis-Betula alleghaniensis||> 200 |
|western hemlock-Sitka spruce||Tsuga heterophylla-Picea sitchensis||> 200 |
|elm-ash-cottonwood||Ulmus-Fraxinus-Populus spp.||< 35 to 200 [11,58]|
In the mixed mesophytic and northern hardwoods ecosystem types of the Northeast, where Norway maple is most commonly reported outside cultivation, fire return intervals range from 35 years to many centuries. Some of these areas, especially those with more frequent fire return intervals and a fire tolerant native flora, may provide suitable conditions for using prescribed fire to control invasive Norway maple.
Fire in mesic forest habitats may spread erratically, leaving a mosaic of burned and unburned patches. Prescribed fire is unlikely to be an effective measure for controlling Norway maple in mesic habitats, since many individuals may remain in unburned patches and other fire refugia.
Effects of fire on colonization and invasive potential of Norway maple are unclear. It does not appear that fire would directly promote an increase in Norway maple recruitment. While there is some indication that seed germination is enhanced by soil disturbance , exposure to mineral soil is not a prerequisite for germination . In the presence of a seed source, Norway maple maintains a continuously-recruited seedling population. Dense populations of Norway maple seedlings have been encountered in relatively undisturbed forests in the northeastern United States [31,59,64]. It appears as long as a seed source is nearby, Norway maple can continue to recruit seedlings without regard to disturbance regime. Fire that removes all Norway maple stems, including the seed source, should eradicate it or substantially reduce its presence. Presumably, recolonization of burned areas can only occur if a) a surviving seed source is present within seed dispersal distance, b) prefire genets survive via postfire sprouting, or c) a low-severity or patchy fire results in survival of one or more stems in fire refugia. Fire could possibly increase the invasive potential of Norway maple by removing a substantial portion of the forest canopy, enhancing opportunities for postfire sprouts or seedling colonizers from an off-site seed source to gain canopy dominance. It is unclear how long it may take for Norway maple to spread beyond seed-dispersal distance of a solitary seed source. It is also unclear how long it may take post-fire sprouts to reach sexual maturity. It seems likely that time frames for either scenario would be highly variable and dependent upon the local environment, especially availability of light.
Use of fire in areas where Norway maple is present may or may not be appropriate, depending on management goals and the particular ecosystem involved. Using fire to control Norway maple in forest habitats where fire is infrequent may do substantial damage to fire-intolerant native species, such as sugar maple and American beech . Conversely, fire may be appropriate where management goals simultaneously include controlling Norway maple and maintaining native seral species or otherwise enhancing ecosystem structure and function, such as oak (Quercus spp.) forests in the eastern U.S. or ponderosa pine (Pinus ponderosa) in the northern Rockies. For more information regarding fire effects on native flora, see the appropriate FEIS species summaries on this website.
Palatability/nutritional value: No information
Cover value: No informationOTHER USES:
Wood Products: Norway maple is used sparingly as a lumber species in Europe for veneer and for specialty items such as tool handles, gun stocks and violins .IMPACTS AND CONTROL:
Norway maple negatively impacts sugar maple/American beech forests of the northeastern United States by dominating the seedling layer and displacing shade tolerant native species [62,64]. In a New Jersey Piedmont mixed hardwood forest, Norway maple seedlings reached densities of 40,500 stems/acre (100,000 stems/ha) or 0.9 stems/ft2 (10 stems/m2) . Norway maple seedlings and saplings appear to be strong understory competitors beneath native species such as sugar maple .
Norway maple may outcompete sugar maple for understory dominance in eastern deciduous forests by exhibiting superior growth. In a Pennsylvania mixed hardwood forest from 1987 to 1991, Norway maple saplings displayed an average annual height growth increment that was nearly twice that of nearby sugar maple . Kloeppel and Abrams  demonstrated how differences in growth may be attributable to physiological characteristics. When daily mean net photosynthesis on a mass basis was compared for saplings of both species at comparable sites throughout a single growing season, values were consistently higher for Norway maple than for sugar maple. Light response curves revealed Norway maple saplings had significantly (P<0.05) higher maximum photosynthetic rates than those of sugar maple, even though saplings of both species had similar respiration rates and light compensation points. Nitrogen and phosphorus use efficiencies were also significantly (P<0.05) higher in Norway maple than in sugar maple on 2 sampling dates. Norway maple saplings also maintained significantly (P<0.05) higher rates of instantaneous water use efficiency than sugar maple saplings at the same site, indicating greater drought tolerance in Norway maple. In addition, average leaf longevity was 12 days longer for Norway maple compared with sugar maple, which probably also contributed to the apparent competitive differences between the 2 species. While these observations represent a single growing season at a single site, they indicate Norway maple may be able to outcompete sugar maple for understory dominance in eastern forests where sugar maple was previously the dominant late-successional species .
Presence of Norway maple in the overstory of northeastern forests may lead to reduced woody species diversity. Norway maple canopy trees appear to be more successful at excluding interspecific woody regeneration than canopy sugar maples . In a New Jersey Piedmont mixed hardwood forest, understory/overstory species relationships were assessed to determine impacts of Norway maple canopy trees on understory species diversity. Although understory species composition was similar beneath Norway maple, sugar maple, and American beech canopies, understory richness was significantly lower beneath Norway maple than beneath sugar maple or beech. Norway maple seedlings comprised 83% of stems and 98% of woody seedlings beneath Norway maple trees . Dense shade provided by Norway maple canopies appears to substantially inhibit woody seedling regeneration, including even Norway maple seedlings . There is concern that Norway maple may alter forest structure by shading out other native understory plant species, such as shrubs and spring ephemeral herbs , although data supporting this assertion are lacking.
The impact of invasive Norway maple in forested natural areas is likely to be closely related to seed source proximity . While Norway maple doesn't require edge habitat to successfully establish, its spread into previously uncolonized forest habitats is accelerated where adjacent development with landscape plantings provides a substantial seed source. Conversely, large unfragmented forest tracts may become colonized by Norway maple more slowly .
More research is needed to determine the nature and extent of risk posed by Norway maple invasion to native plants, plant communities, and ecosystems throughout North America. For example, Norway maple has been identified as a threat for invading conifer forests of west-central Montana .
Control: While removal of overstory Norway maple trees is necessary to end immediate recruitment of Norway maple seedlings, pre-existing Norway maple seedlings and saplings are likely to be abundant and should be removed to enhance growth and survival of native species and to eliminate potential future Norway maple seed sources. Control efforts may require removal of Norway maple trees outside the immediate vicinity of a treatment area due to the influx of seeds from relatively distant sources .
Because removal of Norway maple from a site may entail removing a large proportion of existing plant biomass, drastic changes in site conditions and species composition may result. While such efforts will hopefully benefit native species, there is also substantial risk of facilitating invasion by other nonnative plant species. Removal of overstory Norway maple trees in a New Jersey forest dominated by Norway maple and sugar maple resulted in invasion by new or newly conspicuous nonnatives, including tree of heaven (Ailanthus altissima), Japanese barberry (Berberis thunbergii), winged burning bush (Euonymus alata), Japanese honeysuckle (Lonicera japonica), and garlic mustard (Alliaria petiolata) .
As of this writing, there is very little information concerning control methods for Norway maple in North America.
Prevention: No information
Integrated management: No information
Physical/mechanical: Research was conducted in a 75- to 80-year old New Jersey forest, dominated in all strata by sugar maples and Norway maples, to determine the effects of a) removal of overstory Norway maples, and b) removal of Norway maple seedlings, on Norway maple and sugar maple seedling banks. Felling or girdling of canopy and subcanopy Norway maple trees significantly (P = 0.003) reduced new recruitment of Norway maple seedlings 2 years after treatment. While sugar maple seedling recruitment did not change significantly (P > 0.05) during this period, overall density of sugar maple seedlings was significantly (P = 0.007) higher. Increased sugar maple seedling density was apparently due to enhanced survivorship of older seedlings, stemming from diminished competition with Norway maple seedlings. In contrast, removal of Norway maple seedlings had no significant (P = 0.12) effect on sugar maple seedling density, and merely resulted in rapid recolonization by newly germinated Norway maple seedlings. Soil disturbance resulting from seedling removal treatments was presumed to enhance germination of Norway maple seeds in the seed bank. It was further speculated that had uprooting of overstory trees been included in the canopy removal treatments, further recruitment of Norway maple seedlings would have occurred .
Overstory and subcanopy Norway maple trees that are cut down may resprout from stumps. Larger overstory trees are less likely to produce sprouts that survive for more than a few years, but saplings and subcanopy trees may require further clipping to ensure mortality .
Fire: See Fire Management Considerations.
Biological: No information
Chemical: No informationCultural: No information
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