Improper Pruning & the hidden risks

Quite often in coniferous and deciduous trees, we see architecture that is less than ideal and we often wonder “why?”. Over-extended branches leaning way out over homes, pools, parks, businesses. Co-dominant stems growing and constantly competing for sunlight and dominance. Asymmetrical canopies that look uneven or downright unstable. Trees do weird things, but it’s always for a reason; sunlight. Having a tree in your yard which takes on a concerning stance and stature over time might be worrying to some homeowners.

There are several common misconceptions about pruning trees in various ways to “reduce risk” or generally “make the tree safer”. We’ll focus on two of the most commonly requested practices. 

1. Topping. Topping is the practice of cutting back the upper branches or main stem of a tree to reduce its height and spread. This removes much of the canopy, often leaving large stubs and pruning cuts. 

2. “Lifting” the canopy. This type of pruning can be summed up as removing many of the lower and middle branches of a tree, leaving only upper-canopy branches. Again, this also leaves behind many pruning cuts, often too large for the tree to heal over. In the industry, we often call this “lion’s-tailing” a tree. We don’t recommend topping any tree because it explicitly goes against tree pruning best practices. It also creates some very real challenges for the tree itself, and can even accelerate the tree’s decline. Trees naturally grow with a dominant leading branch, which often presents as the highest, and most vertical branch. By cutting this portion of the tree, we often create a chemical imbalance which causes the tree to push out a surge of new growth from just below the cut. These new sprouts are weakly attached, and can become dangerous years down the road once they’ve grown larger. This is also a new pathway for disease and pests to enter the tree, as a larger cut takes much longer for the tree to compartmentalize and heal over. 

What can we do instead? The correct way to prescribe pruning for a tree that is simply growing too large or overhanging a building or a public area is to use crown reduction pruning techniques. This involves reducing the length of many limbs all over the canopy, usually in the 2-4” diameter range. When these limbs are trimmed, they are cut at lateral branch unions, which is the preferred spot to make a cut. This allows the tree to heal over smaller cuts as opposed to larger. The tree also benefits structurally because it now experiences fewer static stresses and less dynamic forces under wind, snow and ice loading. This pruning can be mildly applied or used to remove an aggressive amount of leaf volume, up to 20% in a single growing season.

Over-pruning the lower portion of a tree can also be destabilizing. This approach can seem appealing because it gets all the lower limbs out of the way and can give the tree more of a “picture perfect” look. However, those looks are deceiving. The tree has grown accustomed to its environment and has filled in its canopy accordingly. Removing many lower limbs can leave the tree more vulnerable to nature’s forces, as it experiences wind much like a flag on a flagpole, with all of the wind catching the higher portions of the tree. This will put more stress on the root system and the trunk of the tree, as there are no more lower dampening branches, which would normally help to absorb some of the force. 

What can we do instead? This often requires us to compromise as tree owners, as we often want what’s best for our trees but place a priority on safety. If lower branches are causing problems on a particular tree, it’s best to select a few branches that may be able to be removed completely, and also a few that could simply be reduced to a nearby lateral branch. We also want to make sure that we’re not just removing branches from down low, we can also focus up higher. Removing a handful of limbs up higher can reduce the amount of wind-sail that the tree experiences, thus helping to keep the entire tree that much more stable. This would be a form of crown thinning, or canopy cleaning. This is recommended to be done on large, mature trees with dense, sprawling canopies. Getting that tree to look just right might take a few years, as this more cautious approach removes less branches in one area, but can effectively achieve the same results over time. Assuming good tree and soil health, scheduling your pruning to occur on 2-3 year intervals will work best. 

Contact us today for a free estimate and experience the difference a true professional tree service makes. 269-491-8644, khtreeservice.com Serving the greater Kalamazoo area, including Mattawan, Paw Paw, Lawton, Portage, Schoolcraft, Vicksburg, Galesburg, Scotts, Plainwell, Oshtemo, Alamo, Cooper, Gobles, Bangor