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Alnus (incana)

Tara Luna
USDI NPS - Glacier National Park
West Glacier, Montana 59936
(406) 888-7835

Family Scientific Name: Betulaceae
Family Common Name: Birch Family
Scientific Name: Alnus incana (L.) Moench tenuifolia (Nutt.) Breitung.
Common Synonym: Alnus tenuifolia Nutt.
Common Name: Mountain alder
Species Code: ALNINC
Ecotype: Forest margin, Lake McDonald drainage, 1000m elev. Glacier National Park, Flathead Co., MT.
General Distribution: A. incana occurs from Alaska to California, east to Nova Scotia and south through the Rocky Mountains to New Mexico. It is common in wet soil of montane swamps, thickets and streambanks.
Propagation Goal: plants
Propagation Method: seed
ProductType: Container (plug)
Stock Type: 172 ml conetainers
Time To Grow: 16 Weeks
Target Specifications: Height: 20 cm<br> Caliper: 7 mm<br> Root System: Firm plug in 172 ml containers and 3 L containers.
Propagule Collection: Seeds are collected in late fall when catkins have turn woody and scales begin to open. Branches are flailed over a canvas tarp and seeds are swept into collection bags and kept in a well ventilated drying shed prior to cleaning.
Propagule Processing: Seeds are extracted by tumbling catkins>It is difficult to separate empty seeds from sound seeds.
Seed Storage: 1 year in sealed containers at 3 to 5C.
Seed dormancy is classified as non dormant.
% Purity: 100%
% Germination: 50%
Pre-Planting Treatments: 24 hour running water soak followed by 60 day cold, moist stratification.
Growing Area Preparation/
Annual Practices for Perennial Crops:
Greenhouse and outdoor nursery growing facility.
Sowing Method: Direct Seeding. Seeds are surface sown for the light requirement.
Growing medium used is 6:1:1 milled sphagnum peat, perlite, and vermiculite with Osmocote controlled release fertilizer (13N:13P2O5:13K2O; 8 to 9 month release rate at 21C) and Micromax fertilizer (12%S, 0.1%B, 0.5%Cu, 12%Fe, 2.5%Mn, 0.05%Mo, 1%Zn) at the rate of 1 gram of Osmocote and 0.20 gram of Micromax per 172 ml conetainer.
Plants are grown in the greenhouse with temperatures maintained at 21 to 25C day and 18C at night for 12 weeks and are moved to outdoor nursery.
Establishment Phase: Germination is uniform and is usually complete in 3 weeks. True leaves appear 2 weeks after germination and seedlings are thinned at this stage.
Length of Establishment Phase: 4 weeks
Active Growth Phase: Seedlings grow at a rapid rate after establishment. Plants are fertilized with 13-13-13 liquid NPK at 100 ppm during the growing season. Plants can be uppotted into 3L (1 gallon) containers 16 weeks after germination, and be root tight in 1 year.
Length of Active Growth Phase: 16 weeks
Hardening Phase: Plants are fertilized with 10-20-20 liquid NPK at 200 ppm in the fall, pots are leached with clear water, one final irrigation is applied before overwintering.
Length of Hardening Phase: 4 weeks
Harvesting, Storage and Shipping: Total Time To Harvest:16 weeks for 172 ml conetainers, 1 year for 3L (1 gallon) containers
Harvest Date:SeptemberStorage Conditions: Overwinter in outdoor nursery under insulating foam cover and snow.
Length of Storage: 5 months
Other Comments: Trees in 3L (1 gallon) containers average 40 cm in height with 2 to 3 cm caliper by the end of the 2nd growing season. Trees in 9L (3 gallon) containers average 1.1 meters in height and can be produced in 3 years from seed.
This species is highly recommended for restoration of riparian zones. It has a rapid growth rate after outplanting and quickly stabilizes streambanks.It is an early seral species in riparian zones and forests.
Alder forms symbiotic relationships with both ectomycorrhizal fungi and Frankia;a nitrogen fixing bacteria. Nursery stock held over in the nursery for longer than one year had formed nodules on the roots.
References: Flora of the Pacific Northwest, Hitchcock and Cronquist, University of Washington Press, 7th printing, 1981.
Seeds of the Woody Plants in the United States, Agriculture Handbook No. 450, U.S.F.S., Washington D.C., 1974.
Seeds of Woody Plants in North America, Young and Young, Dioscorides Press, 1992.
Seed Germination Theory and Practice, 2nd Edition, Deno, N., published June,1993.
Glacier Park Native Plant Nursery Propagation Records, unpublished.
The Reference Manual of Woody Plant Propagation, Dirr and Heuser, Varsity Press, 1987.
The Fire Effects Information System. Missoula, MT: USDA Forest Service, Intermountain Fire Sciences Laboratory.


Luna, Tara; Evans, Jeff; Wick, Dale; Hosokawa, Joy. 2008. Propagation protocol for production of Container (plug) Alnus incana (L.) Moench plants 172 ml conetainers; USDI NPS - Glacier National Park West Glacier, Montana. In: Native Plant Network. URL: http://NativePlantNetwork.org (accessed 2020/10/23). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.

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