Preparing Your Urban Forest For Storms

Written by Josh Behounek

Storm preparation is a huge concern amongst all citizens and departments within a community, urban forestry is no different. When a storm event occurs trees and other woody debris are oftentimes one of the 1st things a community must deal with. Trees will fail and impact roadways, utility lines, street lights, intersections, homes, and people. Figure 1 indicates that trees will fail during storms. Being prepared will minimize negative impacts.

Before power can be restored and primary responders can do their jobs, trees will need to be pruned, removed and cleaned up. While it is impossible to be completely “prepared” for a storm incident it is possible to be ready to react and minimize negative impacts from your trees.

Your urban forest is made up of both public and private trees and this resource is an important part of the community’s infrastructure.  Urban forests provide a host of environmental functions/services from avoiding stormwater runoff, reducing energy consumption, increasing property values, absorbing CO2, and improving the quality of life in a community. Unlike other components of a community’s infrastructure, trees and urban forests continue to appreciate in value as they age and get larger therefore increasing environmental functions/services.

Within a community, there are two types of trees – Assets and Liabilities. Trees that are assets are the right tree planted in the right place for the right reason and do not pose an unacceptable level of risk to the community. Trees that are liabilities do pose an unacceptable level of risk to the community and do not provide environmental function. Like any other piece of community infrastructure, trees need maintenance and upkeep. Part of that maintenance plan should be storm preparation.

When dealing with a storm there are three distinct phases. The initial phase is all about preparation before the storm event. The second phase is what you are doing during the actual storm, and the third phase is following the storm event. For the purposes of this article we will focus the bulk of the discussion around storm preparedness.

Storm Preparation – The Calm Before The Storm

Storms are going to happen and being prepared is a good idea. But what does it mean to prepare your urban forest? At the most basic level an urban forest that is prepared for a storm event will be more resilient. This will save you time and money as well as provide a higher level of service to your residents.

Tree Risk Assessments

We can not make our trees 100% safe all of the time but we can make them safer more of the time by conducting Tree Risk Assessments. Tree risk assessments should be a component of every community’s Urban Forest Management Plan and should be performed by qualified personnel. There are three levels of tree risk assessment that can and should be performed throughout a community. Level 1 inspection is a simple drive-by or walk-by “windshield” survey done annually. Level 2 is a 360° inspection taken from the ground level without the use of specialized equipment. Level 3 inspection is also 360° but involves specialized equipment like an aerial lift, drone, Resistograph, etc

There are many types of tree risk assessment protocols out there but the most common one is the newest Best Management Practice (BMP) developed by the International Society of Arboriculture (ISA). This methodology evaluates the “condition of concern” of a whole tree, branch, or trunk. This ISA BMP methodology evaluates:

  • Likelihood of Failure
  • Likelihood of Impacting a Target
  • Consequences of the Failure

By conducting a regularly scheduled tree risk assessment of your urban forest you can prioritize work that has been identified as posing the most risk. Trees that have the highest risk should be prioritized for needed maintenance such as removal, pruning or cabling/bracing. Another possible option is to move the target like a picnic table, parked car, etc. See the Elgin Case Study Example for how proactive risk mitigation can save you time and money.

Urban Forestry Storm Response and Recovery Plans

Including trees within a community’s storm and/or emergency response plans is highly recommended. As stated earlier, one of the 1st issues that needs to be addressed when responding to a storm is clearing the streets and power lines from downed trees. Communication is key to ensuring that priority services are restored as soon as possible following a storm event. Most communities probably have some sort of emergency response plan or system in place but not a lot incorporate an urban forest specific response plan.

The primary challenge from an urban forestry perspective with these types of plans is that once the initial clean up is completed there is still usually a large amount of debris and work that needs to be dealt with. Immediately following a storm event, the roads and power lines are cleared but homeowners and the community still need to clean up all the other debris. A good Urban Forest Storm Response and Recovery Plan incorporates priority streets to open and remaining debris to manage. This oftentimes includes the use of temporary “marshalling yards”, renting of specialized equipment like tub grinders, and bringing in contractors or using staff from other departments to help.

A tool that can be useful for predicting how much debris a storm may produce is i-Tree Storm. This is a free software created by the USDA Forest Service and can be found at i-Tree Storm uses 2% random street segments to inventory trees > 6” diameter within 50 feet of either side of the right-of-way. By using i-Tree Storm a community can better predict how much debris that will need to be cleaned up following a storm event. This software can also be used immediately following a storm to measure how much debris needs to be cleaned up.

Storm Response and Clean Up

The clean up after a storm event can take anywhere from a couple of days to weeks and months depending on the severity of the storm and the condition of the urban forest. One of the 1st steps that a community should take once a storm has passed is to conduct a Level 1 Rapid Assessment. This windshield “inventory” should be done by a qualified arborist that can properly identify immediate high risk trees. This assessment should be done on all public streets and properties that were affected by the storm. The Texas Forest Service has developed a free Level 1 Tree Risk Assessment mobile app that can be found in the App Store and Google Play.

If the storm is too large for your community to adequately respond there is a high likelihood that FEMA will be deployed.  The US Forest Service in partnership with several state agencies has also developed the Urban Forest Strike Team (UFST). UFST crews can be deployed immediately following a storm to assist communities in need that don’t have staff with urban forest management expertise to reduce unnecessary loss of urban tree canopy. The UFST was created because oftentimes trees are removed that could have recovered and hazardous trees that should have been removed were retained. The UFST can help avoid these types of mistakes.

Storms have the power to cause local and widespread devastation that will affect your urban tree canopy. Being prepared for a storm by implementing proactive management strategies based off of a current tree inventory will help to minimize damage and save your community time and money. By incorporating trees into an Emergency Response Plan or creating an Urban Forest Storm Preparedness Plan you will help your community respond to a storm event efficiently and effectively. Once a storm event has happened it is critical that a Level 1 Tree Assessment be conducted to find high-risk trees. If the event is large enough and outside assistance is warranted then the Urban Forest Strike Team can be brought in to make decisions on what trees should be removed and which should be retained.

Josh Behounek is an ISA Certified Arborist and a member of the Southern Illinois University Agricultural Leadership Board. He is a coordinator of urban forestry services with Davey Resource Group based in central Missouri. 

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