First-year Growth Responses of Young Red Alder Stands to Fertilization

Red alder (Alnus rubra Bong.) is the most abundant deciduous broadleaved tree species in coastal British Columbia. It is a source of products ranging from firewood to furniture, cabinets, and turned-wood novelties (Plank and Willits 1994). In addition, red alder seedlings are planted to restore roads and landings, to stabilize slides, and to reduce laminated root rot (Phellinus weirii) on infected sites. Understanding how to maximize the growth and quality of red alder is important, because more is being planted and harvested in British Columbia. Historically, red alder was unwanted in the Pacific Northwest. In recent years, however, increasing demand for red alder has led to localized shortages in Oregon and Washington (Raettig et al. 1995). In British Columbia, volumes harvested on Crown land have averaged 228 000 m3 per year from 1994 through 1998.1 Meanwhile, the number of red alder seedlings produced for planting on Crown and private land increased from a yearly average of about 14 000 from 1994 to 1996 to a yearly average of 251 000 from 1997 to 1999.2 Silvical characteristics that make alder an appealing species to grow include (1) juvenile growth rates that greatly exceed those of associated conifers on optimal sites, (2) immunity to laminated root rot, and (3) the ability to fix atmospheric nitrogen, in symbiotic association with the soil actinomycete Frankia sp. The ability to fix nitrogen is unique among native trees in British Columbia.