ACMA

Acer macrophyllum

bigleaf maple

Sapindaceae

The Basics

USFS Plant Database

Silvics Manual

Moist woods, forests, and canyons are bigleaf maple's most common habitats throughout much of its distribution... Bigleaf maple often occurs in scattered patches within or on the streamside edges of conifer-dominated riparian communities...Bigleaf maple typically supports many epiphytes. Mosses, liverworts, and ferns hang from its branches or grow in branch crotches. Bigleaf maple's moss load is generally the greatest of all tree species in the Pacific Northwest.

Periodic disturbances such as flooding, fire, or logging apparently help retain bigleaf maple as an important member of seral plant communities. Riparian zones experience flooding frequently...Bigleaf maple is common in primary succession on riverine sites, and it may establish on other new substrates as well...Bigleaf maple can also have positive effects on conifer growth. Litter and debris from bigleaf maple trees and sprout clumps can increase forest floor and soil nutrients and accelerate nutrient and litter turnover in Douglas-fir and western hemlock forests.

The scientific name of bigleaf maple is Acer macrophyllum Pursh (Aceraceae).

Bigleaf maple is common in some conifer, mixed-evergreen, and hardwood communities and in seral brushfields. These communities are often diverse in species composition and structure. Bigleaf maple is associated with Pacific madrone (Arbutus menziesii), Pacific dogwood (Cornus nuttallii), and prince's-pine (Chimaphila) throughout most of its range. Chapters within Barbour and others provide details of other over- and understory species commonly associated with bigleaf maple. In addition to the many vascular plant species with which bigleaf maple is associated, many arboreal moss and lichen species use bigleaf maple as a substrate. (Plant Database)

Identification

Bigleaf maple is a large, deciduous tree. It is typically about 15 m tall at maturity but sometimes grows more than 20 m, making it the largest maple species in North America... It also assumes a shrubby form in montane chaparral...As the common name claims, the leaves of this species are big. Bigleaf maple has the largest leaves of any North American maple, ranging from 10-25 cm across. (Plant Database)

Threats

Bigleaf maple is relatively thin-barked, so it is not fire-resistant. Fire top-kills bigleaf maple in most size classes, although large, mature trees that have developed thick bark may survive moderate-severity fires... Adventitious buds on the root crown enable bigleaf maple to sprout after most fires. (Plant Database)

Fungi are responsible for much of the defect in bigleaf maple. Decay is seldom a serious problem in young undamaged trees, but stem and branch wounds are invaded by wood-rotting fungi such as Heterobasidion annosum, Fomitopsis pinicola, Polyporus berkeleyi, and Inonotus dryadeus that can reduce the tree to a hollow shell. Overmature bigleaf maples are often decayed by root rot (Armillaria spp.) and butt rots (Ganoderma applanatum and Oxyporus populinus).

Bigleaf maple twigs and young stems are browsed by deer and elk. They are also clipped by mountain beavers. The roots are sometimes attacked by nematodes (Meloidogyne spp.). A high percentage of seedling mortality also results from predation by rodents and grazing by slugs and other invertebrates. (Silvics Manual)

Reproduction

Flowering and Fruiting - Bigleaf maple begins to produce seed at about 10 years of age and continues every year thereafter. It is polygamous, and both staminate and perfect flowers are mixed in the same dense, cylindrical racemes. Flowers are greenish yellow and scented, and they appear before the leaves from March, at low elevations and in the southern part of the range, to June, at high elevations and in the north. Pollination by insects usually occurs within 2 to 4 weeks after the buds burst.

Seedling Development - Bigleaf maple seedlings have a high juvenile growth potential, exceeding that of Douglas-fir and other conifers. When open-grown under conditions of adequate moisture and nutrients, seedlings reach heights of 1 to 2 m in one growing season...Temporary flooding is common on riparian sites, and the seedlings are able to survive short periods of inundation.

Vegetative Reproduction - Bigleaf maple sprouts profusely after being cut. The large stumps produce more and taller sprouts, but all sizes regenerate vigorously. Sprout clumps have achieved heights of 5 m and crown diameters of 6.5 m in 3 years, with as many as 67 sprouts around a single stump. (Silvics Manual)

Species Distribution

Bigleaf maple grows in mountainous regions. It is widespread in the Coast Ranges, the Klamath-Siskiyou Mountains, and the foothills of the Cascade Range and the northern Sierra Nevada, obtaining best development in southern Oregon. Some authors place bigleaf maple's distribution as far north as the Alaska panhandle. Isolated bigleaf maple populations may occur in Idaho. (Plant Database)

Citation

USDA Plant Database http://plants.usda.gov/characteristics.html USDA, NRCS. 2016. The PLANTS Database (http://plants.usda.gov, 4 February 2016). National Plant Data Team, Greensboro, NC 27401-4901 USA.

Flora of North America http://www.efloras.org/flora_page.aspx?flora_id=1 Flora of North America Editorial Committee, eds. 1993+. Flora of North America North of Mexico. 19+ vols. New York and Oxford.

Silvics of North America Burns, R.M., and B.H. Honkala. 1990. Silvics of North America (Volume 1: Conifers, Volume 2: Hardwoods). USDA Forest Service Agricultural Handbook 654.

Intermountain Herbarium http://intermountainbiota.org/portal/collections/harvestparams.php Consortium of Intermountain Herbaria. 2016. http//:intermountainbiota.org/portal/index.php. Accessed on February 04.

Burke Museum Plant Image Collection The plant image collection at the Burke Museum, University of Washington.

Jepson Manual http://ucjeps.berkeley.edu/eflora/ The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA., hardcover; 1600 pages. ISBN-13: 978-0520253124.

USGS Plant Species Range Maps http://esp.cr.usgs.gov/data/little/ Critchfield, W.B., and Little, E.L., Jr., 1966, Geographic distribution of the pines of the world: U.S. Department of Agriculture Miscellaneous Publication 991, p. 1-97. Little, E.L., Jr., 1971-1978, Atlas of United States trees, volume 1,3,13,17, conifers and important hardwoods: U.S. Department of Agriculture Miscellaneous Publications.