The City of Moorhead Forestry Division manages and maintains over 26,000 trees along boulevards, parks, and city right-of-ways. Forestry has two types of pruning cycles; a young tree pruning cycle and a neighborhood pruning cycle. The overall goal for pruning trees is the long-term sustainability of the public urban forest. The majority of pruning is done from early November to late March when trees are dormant, decreasing the energy required for the trees to recover. Each season, an average of 2,000–2,500 trees are pruned from targeted pruning areas and from property owner requests. Pruning areas can be found on the City of Moorhead GIS website, along with the year that area was pruned. Moorhead Forestry currently has four ISA certified arborists and follows industry best management practices, including ANSI A300 Tree, Shrub, and Other Woody Plant Management–Standard Practices (Pruning).
Young Tree Pruning Cycle
Forestry prunes all young trees on a 3-4 year cycle for the first 12-15 years after they are planted. Once established in the landscape, young trees grow with great vigor and need to be managed through pruning. One of these needs is clearance pruning. Clearance pruning refers to pruning lower branches of a tree to raise the canopy, which allows for safe and efficient vehicle and pedestrian use along roadways and sidewalks.
Clearance pruning increases sight lines and makes for safer use of roadways and sidewalks. It also encourages the tree to put more energy into growing taller.
Structure pruning, or tree training, is another form of pruning that greatly benefits young trees. This type of pruning mitigates any current or future structural issues the tree may have or could develop. It is important to make these corrections when the tree is young. This ensures the tree can overcome any pruning cuts that are needed and helps it put energy into structurally-sound growth. If these issues are not addressed early, there may be increased risks of branch and tree failures as the tree matures, specifically during storms or wind events. Structural pruning takes place in the canopy of the tree and helps the tree obtain optimal growth habit, height, appearance. and mature structure.
Before (left) and after (right) of a boulevard tree that was structure pruned. This tree had a co-dominant stem reduced, as well as some lower limbs removed. Once mature, the co-dominant structure would have posed an increased risk of storm or wind damage in the form of a crack or split.
Neighborhood Pruning Cycle
Once a tree is no longer part of the young tree pruning cycle, it moves to the 10 year neighborhood pruning cycle. This neighborhood cycle consists of pruning dead, broken, weak, and compromised branches. There may also be a need for some clearance pruning of branches over streets, sidewalks, traffic signs, and away from buildings.
If a property owner would like to have their boulevard tree pruned, a request can be made by contacting Forestry. Property owners are asked to not prune boulevard trees.
For more information on pruning trees and general tree health care, the Tree Owner’s Manual is a great resource.
Clearance Pruning Photo Courtesy of International Society of Arboriculture, Bugwood.org.