Image from USDA plant database¹⁰

Plant Data Sheet: Sitka Mountain-Ash (Sorbus sitchensis)

Range

Sitka mountain-ash may grows in Alaska and south through the Cascade and Olympic Mountains to northern California, and east to Yukon, northern Idaho and northwestern Montana.^2,4

Climate, elevation

Sitka mountain-ash thrives at sea level in Alaska,² and at 2000-10,000 feet elsewhere.⁴ Generally speaking it can be found at middle to subalpine elevations.⁹ Although it is shade tolerant,² it thrives in partial to full sun with moderate moisture.⁷

Local occurrence (where, how common)

Locally Sitka mountain-ash may be found throughout the Olympic Penninsula, Western Washington, and parts of the Okanogan.¹

Habitat preferences

Sitka mountain-ash prefers open, coniferous forests, streambanks, and clearings such as meadow edges and rockslides.⁹

Plant strategy type/successional stage (stress-tolerator, competitor, weedy/colonizer, seral, late successional)

Sitka mountian-ash is a facultative, seral species found mostly in climax forests.²

Associated species

Sitka mountain-ash may be found in the company of conifers.⁸ Among some of the species associated with it are Douglas-fir, Western white pine, Sitka spruce, larch, hemlock, cedar, silver-fir, red-fir, and grand-fir.²

May be collected as: (seed, layered, divisions, etc.)

Sitka mountain-ash may be collected as seed.²

Collection restrictions or guidelines

Sitka mountain-ash produces berries in the summer, which may be collected and thoroughly cleaned to collect the seeds.³

Seed germination (needs dormancy breaking?)

Seeds may be planted in the fall or early winter without stratifying. Otherwise, seeds sown in the spring need stratification of 60 or more days at 32-41°F.²

Seed life (can be stored, short shelf-life, long shelf-life)

Sitka mountain-ash seeds may be stored for 2-8 years.² Germination may be aided by giving a stored seed 2 weeks warmth followed by 14-16 weeks cold stratification.⁸

Recommended seed storage conditions

Information on seed storage conditions was unavailable.

Propagation recommendations (plant seeds, vegetative parts, cuttings, etc.)

It is recommended that Sitka mountain-ash be propagated as seed.^2,8

Soil or medium requirements (inoculum necessary?)

Sitka mountain-ash dislikes dry soils and needs to grow in moist sandy loam, mossy, or medium clay soils. It can tolerate acid, neutral, and alkaline soils.^2,6,8

Installation form (form, potential for successful outcomes, cost)

Sitka mountain-ash may be planted after two years growth, once a root system is built.⁸

Recommended planting density

For 10 inch cubed containerized shrubs, it is recommended that they be planted 3 feet on-center.¹¹

Care requirements after installed (water weekly, water once etc.)

Sitka mountain-ash requires moderate summer watering.⁵

Normal rate of growth or spread; lifespan

Sitka mountain-ash is a deciduous shrub that grows to 4-8 feet, or under some conditions it can grow into a small tree upto 20 feet tall.²

Sources cited

(1) The Burke Museum of Natural History and Culture, Herbarium. http://biology.burke.washington.edu/herbarium. Retrieved April 13, 2006.

(2) Fire Effects Information System, USDA Forest Service. http://www.fs.fed.us/database/feis/index.html. Retrieved April 12, 2006.

(3) Hansen, W. Native Plants of the Northwest. http://www.nwplants.com. Retrieved April 12, 2006.

(4) Hitchcock, C.L. and Cronquist, A. Flora of the Pacific Northwest. University of Washington Press, 2001.

(5) Jepson Horticultural Databse. http://ucjeps.berkeley.edu/cgi-bin/get_hort. Retrieved April 12, 2006.

(6) Oregon State University, Department of Horticulture. http://www.oregonstate.edu/dept/Idplants/3plants.html. Retrieved April 12, 2006.

(7) Permaculture Information Web. http://permaculture.info. Retrieved April 12, 2006.

(8) Plants for a Future. http://www.pfaf.org. Retrieved April 12, 2006.

(9) Pojar, J. and MacKinnon, A. Plants of the Pacific Northwest Coast. Lone Pine Publishing, Vancouver, B.C., 2004.

(10)USDA, NRCS. 2006. The Plants Database, 6 March 2006 (http://plants.usda.gov). National Plant Data Center, Baton Rouge, LA 70874-4490 USA. Retrieved April 12, 2006.

(11)Washington Department of Fish and Wildlife, Planting Considerations and Erosion-Control Fabrics. http://wdfw.wa.gov/hab/. Retrieved April 12, 2006.

Data compiled by (student name and date)

Joy Wood 4/24/06