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Caring for Urban Trees

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urban trees in a city

Urban Tree Care Needs

Urban trees face the same threats as their forest counterparts - disease, storms, insect pests - but they also face unique threats like salt, vehicle damage, compacted soils, limited space, and air pollution. The life of an urban tree can be tough, and trees in developed settings often have shorter lives as a result. Homeowners, building owners, and communities might also be concerned by the potential liability a tree near buildings and public spaces can represent. But caring for urban trees can extend their lives and reduce liability - care and maintenance is critical to preventing accidental injury or damage.

Maybe you've never taken a close look at the trees in your yard or on your street. Trees should be checked regularly (at least once a year) and especially after storms. Most trees do not die suddenly but decline slowly over a few years and checking them regularly will help prevent you being surprised by their death or failure. You can learn how to manage risk in urban trees to help you decide when to call a professional.

Some trees are more likely to be damaged in storms. Some species, such as willows and poplars, are softer and are more likely to be injured. Structural defects such as codominant stems (which is when two or more stems grow upwards from the same point on the main trunk), weak branches, and decay are particularly susceptible to storm damage. Most structural defects can be prevented by proper pruning when trees are young. Removing weak branches and correcting poor form when branches are small will minimize the size of the pruning wounds.

How to Find an Arborist or Tree Care Service

arborists train to take down trees safely

Hiring professionals to assess and care for your trees requires careful consideration. Qualified professionals will perform the work safely and properly to ensure the continued health of your tree. Unqualified people may cause further damage and burden clients with potential liability. Tree care work is hazardous and requires training to perform safely.

Arborists are qualified professionals, certified by the International Arboriculture Society (ISA). ISA Certified arborists receive specialized training and pass a test to become certified and then must maintain their certification through ongoing training and education. You can learn more about ISA certification and find ISA Arborists near you by visiting the ISA Website (leaves DEC website).

Many professionals in the tree care industry may not be certified arborists, but they may be members of the Tree Care Industry Association (TCIA). TCIA offers training, support, and resources to its members. You can learn more about TCIA and find TCIA member companies at their website (leaves DEC website).

Selecting a tree care company can be a challenging task. For the safety of yourself, your family, your property, your neighbors, and your community, it's important to work with qualified professionals. Here are some points to keep in mind when hiring or contracting with an arborist or tree care service:

  • Check online on contractor listing sites or with a web search for tree care services near you.
  • Be cautious of professionals or companies that advertise "topping" as a service - topping is a poor practice, injures trees, and creates weak branches more prone to failure.
  • Ask for certificates of insurance, including proof of liability for person and property damage and workman's compensation. Then contact the insurance company to make sure the policy is current. Under some circumstances you could be held financially responsible if an uninsured worker is hurt on your property or if the worker damages a neighbor's property.
  • Ask for local references or look for references online. If possible, look at the work and speak with former clients.
  • Don't rush into a decision because you are promised a discount if you sign now. Be sure you understand what work is to be done and what the cost is. In general, don't pay in full until the work is completed.
  • Get multiple estimates from different contractors, and let them each know you are soliciting multiple bids.
  • Most reputable tree care companies have all the work they can handle without going door to door. People who are not arborists may solicit tree work after storms, seeing an opportunity to earn quick money. Storm damage creates high risk situations for both workers and property.
  • Legitimate professionals never ask for payment in advance.
  • A conscientious professional will not use climbing spikes except when removing a tree. Climbing spikes open wounds on the tree that can lead to decay.
  • Know that good tree work can be expensive. A good professional must carry several kinds of insurance as well as pay for expensive and specialized equipment. Removing urban trees in close proximity to people and property may require highly specialized equipment and be done slowly. Beware of estimates that fall well below the average because there may be hidden costs or the professional may not be fully insured or trained.

Pruning and Maintenance

Care and maintenance of urban trees ensures their health life and minimizes liability. Trees can be damaged by high winds, snow, ice, and other severe weather events. Some damage requires immediate attention, while other damage may be dealt with later. The primary concern for maintaining trees is safety - safety of the people who live near the tree and safety of anyone working to maintain and prune a tree.

We strongly recommend any work that requires a chain saw or cannot be performed from ground level should be done by a professional tree-care service or arborist.

When weighing the options of whether to prune or maintain your tree here are several things to consider:

  • Insurance: If the tree has structurally failed and the situation is not life-threatening then you may want to contact your insurance carrier before tree work is performed. Many homeowner's policies will cover at least part of the cost of tree removal if there has been damage to structures, houses, or possessions.
  • Be conservative: In the event of damage from storms and weather, clean up anything that imposes an immediate threat or risk while evaluating the tree. Do not prune or remove more than necessary right after the damage has occurred. Damaged trees may still be able to serve the function they were planted for, and removal may be able to be delayed. Trees are stronger than you think and the damage may not be as bad as it first appears. If you're unsure, refer to the advice above on how to find an arborist - they can give you an assessment and make recommendations for saving or removing the tree
  • If the tree is badly damaged and must be removed consider replacing it! Read more about planting trees.
  • Power lines and utilities: Branches hanging over power lines are a major safety hazard from the standpoint of both the person removing the branches, as well as any passers-by. Special training is required to safely prune these branches. Homeowners should not attempt to prune branches near, or laying on, power lines. Contact your local power company for trees and branches near power lines, they will send someone to look at it and provide more information.

Pruning Trees: The Basics

There is a correct way to prune a damaged tree limb, and improper pruning can cause further damage to the tree and hasten it's demise. Safety is the first consideration in removing branches from storm damaged trees. Look up at the whole tree. Use binoculars if necessary. All branches that are loose should be removed as soon as possible to eliminate the chance of injury or damage if they were to fall. Other branches that are cracked or broken should be removed after the loose branches are gone. A branch (or trunk) that was partially stripped of its bark when an attached branch pulled away, and more than a third of the original circumference of bark is lost, should be removed.

Pruning cuts should made so that only branch wood is removed and the trunk or supporting system is not injured. If only branch wood is removed and the wound is small the tree will be able to heal the wound more effectively, thereby reducing the chance of decay. Before broken branches are removed, they should be examined to choose the proper pruning method that will minimize further damage to the branch and the tree. If damage occurs in the winter, remove the broken branches and leave fine pruning and finishing cuts until late winter or early spring. Pruning cuts dry out to some degree in winter, and waiting to cut the damaged limb will minimize die back of the inner bark and help the wound healing process. Try to minimize the live wood removed because the tree is stressed and needs to use stored energy in the limbs to recover. It may take several visits to a tree over time to properly prune it.

Trees and branches that are too large to handle from the ground should only be pruned by professional tree-care services or arborists.

two types of branch unions

Proper Pruning Techniques

If you've determined the pruning can be done safely and without further damage to the tree, then locate the proper place to make a pruning cut. To find the right spot, look for the "branch bark ridge" or "branch collar" on the upper surface of where the branch meets the supporting stem (see reference photo to the right). This is a line of bark that has been pushed up as the branch and supporting stem have grown. Some branch unions will not have this if they did not form properly. Instead, they will have the branch simply pressing into the stem, forming a sharp V-shape.

At the base of the branch, and mostly on the underside, look for the "branch collar," which is a slightly swollen area of stem tissue that wraps around the base of the branch. A proper pruning cut begins just outside the branch bark ridge and angles down and slightly away from the stem, avoiding injury to the branch collar. Branches should be pruned using a series of three cuts: two to remove the weight of the branch (first under then over the branch), then the final pruning cut. Branches that have pulled away from the trunk should be removed at the bottom of the split. Avoid causing any additional damage to the trunk. Remove any loose bark, but do not cut into bark that is living and still attached.

Pruning Don'ts
  • Do not make flush cuts that remove the branch collar. Wounds created by flush cuts cause substantially more injury to the tree than wounds left by proper pruning.
  • Do not top trees! Topping trees creates serious hazards and dramatically shortens a tree's life. Branches resulting from topping cuts have very weak attachments and become hazards as they grow.
  • If you are pruning oak trees, avoid pruning them in spring or summer unless absolutely necessary. Pruning in warm months can spread oak wilt because the insects that spread the disease are active during these seasons. Read more about oak wilt and how you can help.
  • In general, do not use paint or wound dressings on cut surfaces (with the exception of damage to oak trees in spring and summer), these materials may interfere with wound healing.