Rocky Mountain Douglas-fir facts for kids
Quick facts for kids Rocky Mountain Douglas-fir |
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| Rocky Mountain Douglas-fir forest in Pike National Forest, Colorado (United States) | |
Scientific classification  |
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| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Pinales |
| Family: | Pinaceae |
| Genus: | Pseudotsuga |
| Species: | |
| Varietas: |
P. m. var. glauca
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| Trinomial name | |
| Pseudotsuga menziesii var. glauca (Mayr) Franco
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The Rocky Mountain Douglas-fir (scientific name: Pseudotsuga menziesii var. glauca) is a type of evergreen tree. This means it keeps its needles all year long. It is a conifer, which is a tree that produces cones.
You can find this tree in the mountains of western North America. Its home stretches from central British Columbia in Canada, south through the United States, and into northern Mexico. It grows in the Rocky Mountains and on high "sky islands" in states like Utah, Colorado, and Arizona.
This tree grows at different heights, from about 600 meters (2,000 feet) in the north to over 3,000 meters (9,800 feet) in the south. Closer to the Pacific Ocean, you'll find its cousin, the Coast Douglas-fir. In southern areas, the Mexican Douglas-fir takes its place.
Scientists usually call the Rocky Mountain Douglas-fir a "variety" of the main Douglas-fir species. This means it's a special type that has adapted to its mountain home.
Contents
Amazing Tree Features
The Rocky Mountain Douglas-fir is a very large tree. It often grows to be 35 to 45 meters (115 to 148 feet) tall. Some special trees can even reach 67 meters (220 feet) tall! Its trunk can be about 1 meter (3 feet) wide, with some growing to 2 meters (6.5 feet) wide.
These trees can live for a very long time, often over 500 years. Some have even lived for more than 1,200 years!
Bark and Needles
When the tree is young, its bark is thin, smooth, and gray. It has small bumps filled with sticky resin. As the tree gets older, its bark becomes thicker, about 3 to 6 centimeters (1 to 2.5 inches) thick. It gets grooves and feels corky.
The small branches, called shoots, are brown or gray-brown and have tiny hairs. The tree's buds are shaped like narrow cones and are reddish-brown. The leaves are like needles, about 2 to 3 centimeters (0.8 to 1.2 inches) long. They are gray-green to blue-green and have white lines on the underside.
Reproduction: Cones and Seeds
Male cones, which produce pollen, are about 2 to 3 centimeters (0.8 to 1.2 inches) long. They are usually found on the lower branches. These cones grow for a year, and then they release pollen into the wind in the spring.
Left: Shuswap Lake, British Columbia, Canada
Right: Chiricahua Mountains, Arizona, U.S.
Female seed cones hang down from the branches. They are 4 to 7 centimeters (1.6 to 2.8 inches) long when closed. When they open, they are about 3 to 4 centimeters (1.2 to 1.6 inches) wide. They start out purple (or sometimes green) in the spring. By autumn, about 5 to 7 months later, they turn orange-brown.
Inside these cones are the seeds. Each seed is about 5 to 6 millimeters (0.2 inches) long and has a wing. This wing helps the seed fly away in the wind. Both Rocky Mountain Douglas-fir and Coast Douglas-fir trees produce lots of seeds every 2 to 11 years. They make seeds almost every year, except for about one year out of every four or five.
How They Grow
Rocky Mountain Douglas-fir trees grow slower than Coast Douglas-fir trees. But they are much better at handling cold weather. Different groups of these trees can handle cold differently, even if they grow close to each other.
Roots and Seed Spreading
When the tree's roots can grow freely, they form a strong main root called a taproot within a few years. Other roots spread out like ropes in the soil. New small roots grow and die often, usually lasting a few days to a few weeks.
These trees can start making seeds when they are 12 to 15 years old. Their winged seeds are mostly carried by wind and gravity. Most seeds fall within 100 meters (330 feet) of the parent tree. However, some seeds can travel much farther, sometimes 1 to 2 kilometers (0.6 to 1.2 miles)! Small animals like mice, chipmunks, and squirrels also help spread the seeds.
How Long They Live
The oldest Rocky Mountain Douglas-fir tree that has been accurately dated is 1,275 years old. It lives in New Mexico. This tree has been protected from fires, animals, and people because it grows on a rocky lava field.
In some dry forests in British Columbia, these trees can live for over 500 years. Some old trees that have avoided logging and fires are known to be from the 1500s and 1600s.
Tree Health Challenges
Like all living things, Rocky Mountain Douglas-fir trees can get sick or be bothered by insects.
Diseases
Some diseases that affect these trees include Phaeolus schweinitzii, Armillaria, Phellinus weirii, and Fomes annosus. They can also get dwarf mistletoe, Dasyscypha canker, and Rhabdocline needle cast.
Insects
Certain insects are attracted to the Douglas-fir. These include the Douglas fir beetle, western budworm, and tussock moth.
Living with Nature
The Rocky Mountain Douglas-fir grows in many different places. You can find it at lower elevations near grassy areas and also in high mountain forests. It is most common in low and middle elevation forests.
Animals and the Douglas-fir
Many animals depend on the Rocky Mountain Douglas-fir.
- In spring and winter, elk eat the branches of young Douglas-fir trees.
- In Yellowstone National Park, elk eat so many young trees that they stay small, only about 1 to 1.5 meters (3 to 5 feet) tall.
- White-tailed deer and mule deer use these trees for shelter and food in winter.
- Moose also eat Douglas-fir when their favorite food, willow, is not available.
Small animals like chipmunks, mice, voles, and shrews eat many conifer seeds from the forest floor. Squirrels store large amounts of Douglas-fir cones and seeds for food. American marten often make their homes in hollow logs from these trees.
Many songbirds eat seeds from Douglas-fir cones or find them on the ground. These include the Clark's nutcracker, black-capped chickadee, red crossbill, and pine siskin. Woodpeckers often feed on insects found in the bark. Blue grouse eat the needles and buds in winter. Many birds also use Douglas-fir forests for protection.
The Douglas-fir can also be affected by a tiny insect called the Adelges cooleyi, which is a type of woolly aphid. This aphid also lives on the Engelmann spruce as part of its life cycle.
What We Use Them For
The wood from the Rocky Mountain Douglas-fir is very strong and useful. It is used for many things:
- Building materials like plywood and lumber.
- Poles, railroad ties, and mine timbers.
- Log cabins, fence posts, and firewood.
- Furniture, cabinets, doors, and flooring.
Rocky Mountain Douglas-firs are also popular as Christmas trees!
Images for kids
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Young seed cone
See also
In Spanish: Douglasia de montaña para niños
