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Alnus is the genus of Alder. Red alder (**Alnus rubra**) is a common species, that establishes from small wind-borne seed on bare soils. It fixed nitrogen with a bacterial symbiont. There are additional species **Alnus sitchensis** that is common to higher elevations and landslides, with a different morphology.

Notes on Alnus rubra

Notes on Cultivation and Use of Alnus Rubra

  • Along with Populus and Salix among our fastest growing hardwood trees.
  • Alder does form adventitious roots on trunks buried by flooding, but does not root well from cuttings.
  • Small rapidly planted propagules such as 1-year 12 cubic inch tubes, or 1-0 bare root stock can grow to 2-4 feet in one year, making use of older or potted stock of questionable cost-effectiveness.
  • Alder may naturally establish on bare ground where there is a seed source, and become dominant, requiring management to support other plantings.
  • High density stands can produce brittle thin trunks, exacerbating the natural weakness of stems, making the tree prone to damage from wind or ice.
  • Alder can force rapid tall growth of neighboring conifers.
  • Alder are prone to fungal infection, and will not reliably stump sprout (perhaps due to fungal attack?)
  • Alder seems to favor moist sites, but is broadly adapted - the limits to drought tolerance are unclear.
  • Alder may serve well as a nurse crop for forest restoration. Young dense stands are reliable and cost effective to establish even in pasture. After 3-5 years, pasture is suppressed, aggressive thinning can be accomplished with a machete or machinery, and will create copious mulch and niches for a more diverse planting. These methods are not commonly used in part because of how we fund revegetation projects.