Red alder, or Alnus rubra, also goes by the names western alder, Oregon alder and Pacific Coast alder. It is the most common of the hardwoods found in the Pacific Northwest. This conifer is relatively short-lived with a lower commercial value than other alders. Thus, forest managers usually eliminate it from conifer stands. Because red alder are so common, they are often considered weed trees. However, they can be used to make fine cabinets and furniture. Pruning them improves their appearance and health.
Consider the pyramidal form of the red alder. It has a strong central stem and lateral branches that grow horizontally and don't compete with the central stem for dominance. If you try to shape the tree into an unnatural form, you'll have to do continuous maintenance. So it's best to go with its natural shape.
Prune red alder when they are young in order to produce a strong structure. As they mature, the purpose of pruning is to maintain the tree structure, health, form and appearance.
Use a hand pruner to cut small, thin branches. Lopping shears or small pruning saws can be used for slightly larger branches with bigger cutting surfaces and greater leverage. If you're dealing with even larger branches, about six inches thick, use a pruning saw. Chainsaws will work on branches thicker than eight inches.
Plan to make cuts at the node, which is where one twig or branch meets another. Each spring, growth will start with buds, and twigs grow until there is a new node.
Remove branches with narrow, V-shaped connections, because they are weaker and are likely already cracked. Keep all branches that are attached with strong U-shaped joints.
To achieve crown raising, remove all the branches that are at the bottom of the tree to create space between the red alder's branches and the ground. The tree will have a neater appearance this way.