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
- http://biology.burke.washington.edu/herbarium/imagecollection.php?Genus=Alnus&Species=rubra - best source for images
- https://en.wikipedia.org/wiki/Alnus_rubra - general overview.
- https://plants.usda.gov/core/profile?symbol=alru2 - describes in context of USA and wetland determination
- http://eol.org/pages/1145612/details - general taxanomic description
- http://owic.oregonstate.edu/red-alder-alnus-rubra - more thorough description of alder as a forestry species.
- File:Puettmann et al 1993 alder density management.pdf
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.