What’s the Difference and Why it Matters
When people ask for help pruning their trees, many aren’t sure what to ask for. Tree trimming or pruning? They know their trees need work but they don’t how to describe it. Tree service ads don’t help. They use terms such as trimming, cutting, topping, rounding, crowning, heading, shearing, lacing, sculpting, wind-sailing and the list goes on. The words describe pruning operations but don’t explain what will be done. They leave tree owners scratching their heads and often disappointed with the results.
To help clear up the confusion, the American National Standards Institute (ANSI) developed a pruning standard called the the ANSI A300. The A300, based on best management practices for tree health and safety, was created to help arborists write better pruning specifications so tree owners would know what work was being done.
The A300 recommends that proposals clearly state:
Pruning objectives: Such as structural improvement, size reduction, building clearance, etc.
Pruning types to be used: Such as crown cleaning, thinning, raising, reducing and restoring.
Minimum and maximum branch diameter for cuts: ½ inch, 2 inch, 6 inch, etc.
Maximum % of foliage removed: 5%, 10%, 25%, etc.
Tree pruning specifications are to an arborist what a set of blueprints is to a building contractor. They define the pruning outcomes that are planned and how they will be achieved. They tell what will and will not be done. They put the contractor, the tree owner and the crew all on the same page. And in the end, they clarify expectations and create a win-win for everyone.
When contracting for tree pruning services, request that your tree care provider define terms, establish clear objectives and describe the specific pruning types the workers will employ to achieve those objectives. If service providers have difficulty describing the scope of work and measurable outcomes, it may be an indication that they lack the knowledge and skill to prune trees correctly. And the last thing you want is for your trees to be damaged, sometimes beyond repair, by unacceptable pruning practices such as topping or lion’s tailing.
For a better experience, consider selecting a qualified company that provides clear pruning specifications based on the ANSI A300. You’ll be glad you did, and so will your trees!
Rain and Wind Dynamics
Wind forces act upon trees in unique ways depending on the distribution of foliage throughout the entire tree crown as well as along individual branches. Thinning cuts as well as reduction cuts help reduce the drag (wind resistance) on the tree canopy and lower the height of the pressure center to larger diameter wood. To prepare your trees for summer winds, a combination of both types of pruning is needed but especially reduction pruning. Research has shown that reduction pruning to alleviate end weight is the best type of pruning to decrease risk of tree and branch failure.
A big mistake is to over-thin trees with the idea that this makes them safer. There is an unacceptable pruning technique called Lion’s Tailing that removes an excessive number of smaller branches from a tree’s interior at the neglect of the outer third of the crown. You’ve probably seen these sorry, stripped-out specimens on your street. The wind blows through their lower crown but is concentrated now in the lion tails of heavy foliage that flag in the wind and often break. Properly thinned branches have an even distribution of foliage along the entire length of the branch. Consequently the force of the wind is now evenly distributed along the length of the branch, transferring that force to the base of the branch where the diameter is greater and it can better support the branch movement.
Tips to prepare your trees for summer storms:
If you prune your own trees, consider attending one of my upcoming pruning classes. I will be teaching a class at the Desert Botanical Garden on June 22nd. Click here for more information or to register.
To prepare your trees for summer, there is nothing more important than proper watering. Doing it well can be a challenge in the desert, but the following tips should help.
Stay tuned for my series on Irrigation next month. In the meantime, for a closer look at watering and using a soil probe, visit our Integrity Tree Service Fact Sheets here.