The Mountain hemlock (Tsuga Mertensiana) is a member of the pine tree family. It is a very slow-growing tree that grows on cold, snowy sub-alpine sites. Some of these trees grow to be more than 800 years old. They add unique beauty to many mountain landscapes. This type of tree has light-colored wood, and it is moderately strong and favored for pulp and lumber. You can find this tree growing in Sequoia National Park in California. Other places it can be found growing are Alaska, Nevada, Oregon, Washington, Idaho and British Columbia. They thrive in cool-to-cold climates. The mountain hemlock can grow at altitudes of 300 to 1,000 meters. The soils they grow in vary and can be volcanic, sedimentary, metamorphic and glacial.
The mountain hemlock grows in isolated populations. They can be found among mixtures of other trees. In the state of Oregon, there are pure mountain hemlock forests. These trees release pollen and produce buds, and the seeds of the mountain hemlock are dispersed by the wind. This type of tree can be really slow to regenerate, especially after logging and wildfires. In wildfire areas, some of the mountain hemlocks that are destroyed are 20 to 40 years old. The regeneration of this tree varies in response to environmental factors. The small saplings of the mountain hemlock are able to tolerate very heavy snow-packs. After the snow melts, the bent branches spring up erect.
The mature mountain hemlocks can range in height from 15 meters to 46 meters. The mountain hemlock grows much slower than the western hemlock. These trees have shallow roots, and the roots are confined to the forest floor. They are able to tolerate shade very well. The mountain hemlock can attract a fungus called laminated root rot. This is a fungus that can kill the tree as it spreads along the tree to its roots. This fungus has infected areas of more than 100 acres. Low levels of nitrogen in the soil can add stress to this type of tree. This can lead to the tree attracting the fungal infection. Heart rot and Indian paint fungus are other infections that attack the mountain hemlock. There are a few needle diseases and snow mold that are known to attack this tree. This tree has a very long history and the race of the mountain hemlock can be traced to the dwarf mistletoe.