Pamela Lovell: Proper Way to Trim Trees

Do you have a street tree in front of your house or business?

The trees of San Francisco are a resource for all of us. They increase property values, decrease runoff into our sewers, consume carbon dioxide, increase foot traffic and serve as habitat for birds. But, overly aggressive pruning techniques are on the rise. Here are some important facts for all of us to consider.

Let's say you have a street tree in front of your house that you want to alter for more light, a better view, higher visibility for your signage, or less leaf drop.

You hire someone to prune your tree. The price seems reasonable. When you return, you discover your tree looks very much like the one in the above photo. In this scenario, 99 percent of the canopy has been removed. Your tree has been "topped," or "hat-racked."

The tree in this photo has been hopelessly compromised and will likely die. Now you have opened yourself to the real possibility that the City's Bureau of Urban Forestry will fine you. While a street tree is your responsibility, it is not your tree to do with what you will. The fines are hefty and will include a requirement to remove the tree and its stump and replant; replant with a large specimen, not the 15-gallon size you see during Friends of the Urban Forest's plantings.

In another scenario, the tree workers prune your tree aggressively but leave some of the canopy. Your tree's response will be to accelerate its growth to try and survive. Sure, it will "fill in," but with sucker growth (also called water sprouts), which are poorly attached and are unlikely to become well attached branches. They will, however, leave your tree open to pests and disease and potential branch failure. Adding insult to injury, you will have to have the same work performed every year.

To avoid these outcomes, hire a qualified arborist (this will be slightly more expensive, but you will get more value for your money), inform yourself and learn the ways to achieve your goals using proper pruning techniques. Stay on site to manage the process and do not allow more than 25 percent of the canopy to be removed.

For more information about proper street tree care, contact the following sources on the Internet:

• Friends of the Urban Forest (FUF.net): Volunteer for tree care and/or find qualified arborists to do the work. Be sure to read its tree topping article - it is an eye-opener;

• PowerLearning21.com: An online video is available for a small fee about pruning (which I helped create);

• International Society of Arboriculture (treesaregood.com): A good source for more names of arborists and educational sites.

Pamela Lovell is a certified arborist with nine years experience in the field. For more information, contact her at arborsf18@aol.com.