Bigleaf maple trees (Acer macrophyllum) are not maples for small yards. These deciduous trees can grow to over 100 feet (30 m) tall with a similar spread. But anyone with a large property might consider giving it a go, as long as they have the proper bigleaf maple habitat. Where do bigleaf maple trees grow? It’s a good question to ask before planting one of these trees in your garden. Read on for more information about bigleaf maple habitat as well as facts about the trees themselves.
I. Appearance and Characteristics
Acer macrophyllum, the bigleaf maple or Oregon maple, is a large deciduous tree in the genus Acer. It is native to western North America. In addition to uses by animals, it is of some culinary and woodworking interest.
Bigleaf maple can grow up to 48 metres (158 feet) tall, but more commonly reaches 15–20 m (50–65 ft) tall and 90–120 centimetres (35–47 inches). The species’ current national champion for size is located in Lane County, Oregon. It is 36 m (119 ft) tall with a crown spread of 28 m (91 ft), with an average diameter at breast height (dbh) of about 3.7 m (12 ft). The previous national champion is located in Marion, Oregon, and is 27 m (88 ft) tall with a crown spread of 32 m (104 ft), with an average dbh of about 2.5 m (8 ft). The bark is gray brown, darkening and developing ridges with age.
The bigleaf maple has the largest leaves of any maple, typically 15–30 cm (6–12 in) across with five deeply incised palmate lobes, with the largest running to 61 cm (24 in). The stems are 15–30 cm (6–12 in) long and contain milky sap. In autumn, the leaves turn gold and yellow, contrasting against backdrops of evergreen conifers. In spring, the tree produces flowers in pendulous racemes 10–15 cm (4–6 in) long, greenish-yellow with inconspicuous petals. It is hermaphroditic, bearing both male and female flowers in each raceme. The flowers appear in early spring, before the leaves. The fruit is a paired winged samara, each seed 1–1.5 cm (3⁄8–5⁄8 in) in diameter with a 4–5 cm (1+5⁄8–2 in) wing. Bigleaf maple begins bearing seed at about ten years of age.
In May 2018 the oldest two Oregon maples in Europe, 175 years old, were removed from Trinity College Dublin (TCD), Ireland. The first had an interior which was beginning to rot, and it fell after inclement windy weather. The second, also infected, was cut down as the same fate was expected. Both were in the adjoining grassy area which was originally the cemetery of All Hallows and is now the Front Square of TCD.
The tree can live in a wide range of habitats, but thrives in fairly well-hydrated hardwood forests, occurring with red alder, black cottonwood, and willows. It is fairly shade tolerant, but not as much so as vine maple, and benefits from disturbances. It is not considered to be fire-resistant due to its thin bark, but large trees with thick bark may survive moderate fires. Along with red alder, bigleaf maple often dominates early postfire succession in Douglas-fir forests, and fire can increase its forest presence. It spreads and grows vegetatively from cuttings and stumps of any size in a prolific manner.
Insects fertilize the tree’s flowers. The winged fruits are eaten by squirrels, and by grosbeaks in the winter. Deer mice have been observed consuming bigleaf maple seeds in the spring in the Sierra Nevada. The foliage is browsed by ungulates such as black-tailed deer, mule deer, elk, and horses, as well as by mountain beavers and other rodents. A western Oregon study found that 60% of bigleaf maple seedlings over 25 cm (10 in) tall had been browsed by deer, most several times.
Bigleaf maple is preferred as habitat by the barred owl, an invasive species to coast range habitat, and the presence of the tree is positively associated with Hammond’s flycatchers.
In the wetter parts of its range, such as in the Olympic National Park and lowland forest around Puget Sound, the bark is often covered with epiphytes such as club moss and licorice fern.
Older trees suffer from heart rot.
II. How to Grow and Care
Sunlight
The bigleaf maple has a certain requirement for sunlight and prefers a partially shaded area. In cases of exposure to direct sunlight in the summer, the leaves of most varieties will wither, so shading is required. As the plants get older and their root system grows, this condition will be less of a problem. A few varieties will tolerate exposure to direct sunlight, such as ‘Beni Maiko’ and ‘De Shojo’. Some weeping varieties can also tolerate exposure to direct sunlight, such as ‘Ao Shidare’.
Sunlight conditions will directly affect the ornamental appearance of bigleaf maple leaves. In the spring, sufficient sunlight will make the maple leaves more vivid, while in cases of insufficient sunlight or partial shading the leaf color may fade. During the fall, sunlight can also affect the leaf color. For potted plants, full exposure to sunlight is recommended during the spring and the fall, with partial shading in the summer.
Temperature
The bigleaf maple has good cold resistance and is able to tolerate low temperatures. The bigleaf maple is native to the margins of forests in China, Japan, and North Korea, so these trees generally prefer a humid environment. Most bigleaf maple plants have shallow root systems, so they should be watered frequently during the summer. For some varieties, a sprayed mist should be provided during the summer to increase the humidity of the air around them.
Watering
The bigleaf maple prefers the soil to be kept moist, especially during the summer, because dry weather can cause its leaves to scorch and even fall off in severe cases. During the summer, in addition to watering the roots, foliage can be sprayed during the evening to increase the humidity.
- In the summer, seedlings growing in pots may need watering twice a day, in the morning and the evening.
- In the spring and fall, watering should be carried out depending on the actual conditions. Watering can be reduced slightly as the temperature drops in the fall, which will help the leaves to change color.
- In the winter, it is only necessary to ensure that the soil does not dry out.
Attention should be paid to the watering of seedlings grown in gardens during the early stages. At later stages, water should be supplied according to the weather, that is if there is no rain for more than two weeks in the summer.
Soil
The bigleaf maple does not have many specific requirements for soil. It is a forest native, so it prefers well-drained soil that is rich in humus and slightly acidic. Its main root will extend deep into the soil, but its tiny fibrous roots will be concentrated near the soil surface, so accumulated water in the soil tends to cause root rot.
Fertilizing
Potted seedlings should be given slow-release fertilizer only. For seedlings grown in gardens, fertilizer should be applied three times a year: once in the early spring, once in early summer for the growth period, and once in the fall.
Planting Instructions
The best time for planting or transplanting a bigleaf maple is following defoliation in the fall. At this time, the leaves will have fallen off so there is little transpiration and water loss can be avoided. In addition, the root system will still be growing at this time, preparing for regrowth the following spring. Transplanting should be avoided on the coldest days because cold wind can kill some of the shoots and branches. During the winter, in areas that cannot be sheltered from the wind, it is recommended to cover the branches.
Pruning
Pruning is mainly used to enhance internal ventilation, improve shoot formation, promote growth, and for shaping. The common approach to pruning is to remove any old or weak branches, remove any branches that disrupt the shape of the tree, and remove any branches that cross other branches. Pruning is used to control the plant according to the required height and shape. Generally, this follows the “Y-type” pruning method.
It is possible to prune a bigleaf maple throughout the year, but the coldest winter months should be avoided to prevent damage to the plant. Major pruning to shape a maple can be performed following defoliation in the fall, or prior to leaf growth in the spring. It is recommended to prune in the fall because withered and full buds can be easily distinguished.
According to the shaping plan, you can prune any withered buds and keep the full ones, thus making your tree healthier. For pruning in the summer, diseased, weak, or dead branches can be removed, mainly to enhance the tree’s ventilation.
If grown as a potted plant, the roots can easily occupy the entire flowerpot due to the limited space. This can make a bigleaf maple prone to aging if an old flowerpot is not changed. It is recommended that old roots are pruned during the dormancy period, that is, cut off any old, coarse, diseased, and weak roots.
Propagation
Common propagation methods include grafting, taking cuttings, and sowing seeds.
Grafting is the most common propagation method. Seedlings of Acer palmatum or Acer oliverianum are usually selected for the rootstock. Grafted seedlings have strong roots and grow rapidly, but poor affinity is occasionally present in some cases. Seedlings with Acer oliverianum as the rootstock are less hardy.
Cuttings take longer to grow and are mostly used in the production of bonsai.
Sowing seeds is a common way to cultivate new varieties. The hybrid offspring of two different maples are sown and valuable individuals are then selected from the seedlings. The traits of the parents may not be maintained in the selected offspring.
Transplanting
For bigleaf maple, the preferable transplanting period is late spring to early summer, when the plant is not actively growing. This timing allows bigleaf maple to adapt comfortably to new environments. The ideal location should have well-drained soil and some wind protection. Water it regularly after transplanting for better growth.
III. Uses and Benefits
- Ornamental uses
The bigleaf maple is valued in landscaping projects that can accommodate its size; it is one of the widest-growing maple trees, with hefty leaves. Mature trees provide excellent shade, and their golden leaves are a brilliant display in autumn. They would be at home on vaster properties, planted with very shade-tolerant species beneath, with ample room for the wide spread of their sheltering branches.
- Culinary uses
Maple syrup has been made from the sap of bigleaf maple trees. While the sugar concentration is about the same as in Acer saccharum (sugar maple), the flavor is somewhat different. Interest in commercially producing syrup from bigleaf maple sap has been limited. Although not traditionally used for syrup production, it takes about 40 volumes of sap to produce 1 volume of maple syrup.
- Other uses
The bigleaf maple is the only commercially important maple of the Pacific Coast region.
The wood is primarily used in veneer production for furniture, but is also used in musical instrument production (including piano frames), interior paneling, and other hardwood products; the heartwood is light reddish-brown, fine-grained, moderately heavy, and fairly robust. It sometimes shows a quilted figure.
