Surviving the Storm

Preparing Trees to Stand Up to Winter

As winter tightens its icy grip across North America,  preparing trees for the cold months ahead is paramount. Heavy snow, frigid ice, and fierce winds can transform enchanting winter wonderlands into bone-chilling graveyards for trees, leaving them vulnerable to damage that poses serious safety hazards and a significant risk of injury.

Luckily, there is a way to weather the storm. By conducting comprehensive risk assessments and addressing other critical preparatory tasks, trees can be fortified against the winter elements to safeguard not only people and property but also promote their health and resilience to ensure they remain steadfast and beautiful all year round.

Risky Business

Winter storms pose a significant threat to trees, with elements like snow, ice, and wind, often leading to substantial, irreversible damage. Trees that are poorly maintained, structurally deficient, shallowly- rooted, weak, or stressed are especially vulnerable to harsh winter conditions as they lack structural integrity and mechanical strength compared to healthy, deeply-rooted trees. While healthy trees stand a    better chance of surviving stormy weather, this does not mean they are immune to risk.

In tree biomechanics, failure occurs when load exceeds strength, either through overload failure (i.e., single load application) or fatigue failure (i.e., repetitive load over time). In other words, when forces like snow, ice, and wind are above the tree’s capacity to support that load, whether suddenly or gradually, it fails.

This principle is true for any tree — not just weak or stressed trees. This is why even healthy, structurally sound trees can suddenly succumb to extreme weather forces. Winter conditions can generate both overload and fatigue failure in a tree’s architecture, which dramatically increases the likelihood of failure during storms.

Contributors to failure are not limited to snow, ice, and wind. Freeze-thaw cycles caused by day-night temperature fluctuations can result in vertical cracks or sloughed bark, exacerbating weak structure and exposing the tree’s vascular system to disease and decay. Additionally, pollutants such as de-icers can cause chemical imbalances in the soil, leading to physiological problems like desiccation and nutritional deficiencies.

Preparing trees for winter storms is essential not only to minimize these risks, but also to prevent death, injury, or costly damage to people and property.

Proactive Measures: High Risk, High Reward

As the old saying goes, “an ounce of prevention is worth a pound of cure.” Taking proactive measures to prepare trees for winter storms offers many benefits to homeowners and professionals alike:

• Preventive Care: Assessing trees prior to winter storms and performing proper tree care maintenance throughout the year can help prevent limbs or entire trees from falling on people, vehicles, buildings, and other property.
• Increased Tree Resilience: Trees that are well-maintained with best management practices like pruning, mulching, watering, and fertilizing are more likely to recover from storms and survive the winter season in good health.
• Safer Working Conditions: If trees are properly assessed and maintained in advance, tree care professionals who respond to post-storm events will face fewer risks when working in the field. This thereby reduces the likelihood of injury during storm recovery.
• Protection of People and Property: Be sure to review insurance coverage with an agent or broker before or during the season. By working with a partner that knows the risks of the industry during winter months, you can be sure your policy addresses potential working hazards and prevents costly gaps in protection.

Tim Greifenkamp, TreePro program manager at NIP Group, emphasizes the importance of preparation: “Winter brings unique challenges for tree care companies… By being proactive, you not only safeguard your business financially but also position yourself to focus on safe operations and storm recovery with peace of mind during the most demanding months of the year.”

Conducting Risk Assessments

Before winter arrives, it is critical to conduct a comprehensive risk assessment for trees that may be vulnerable to storm damage. A Tree Risk Assessment (TRA) is a process that evaluates a tree’s overall risk rating by identifying structural defects, hazards, and other environmental factors that could increase the likelihood of failure, impact, and consequence to people or property.

The goal of a TRA is to analyze the intersection between these factors and recommend mitigation options that effectively minimize risk. This evaluation identifies potential problems in trees and highlights which ones are most at risk during a winter storm — before it happens. When performed correctly, a TRA can help prevent accidents and save lives.

“If a known stormfront is approaching it’s always wise to do a pre-storm tree inspection,” said Christian Wissmuller, communications specialist with CMC North America. “Remove dead tree limbs, trim any low-hanging branches, and make sure that all doors, windows, and power lines are clear.”

During the assessment, consider the following factors:

• Species: Different tree species exhibit varying susceptibilities to adverse weather conditions based on the strength, integrity, and attachment of their wood. Species with weak structure (e.g., cottonwoods, willows, maples, etc.) are more prone to failure, whereas species with strong structure (e.g., oaks, magnolias, sweetgums, etc.), are less prone to failure.
• Structure: Tree architecture plays a vital role in winter storm resilience. Key structures like roots, trunks, branches, unions, and form determine a tree’s ability to withstand strong forces. Look for unstable roots, high-angled leans, codominant stems, and other structural weaknesses.
• Size, Age, & Condition: Larger, older, and stressed trees are more likely to suffer significant damage during winter storms. Look for trees that are in poor health with pest or disease infestations, fungal conks or bracts, cracks, previous storm damage, or other signs of weakness.
• Environment: Soil quality and proximity to construction, roads, or structures can influence tree stability. The more urbanized the environment, the higher the potential risk to the tree and its surroundings.
• Location & Proximity to Targets: Trees located near roads, buildings, and powerlines pose a higher risk to people, property, and activities during storm events.
• Frequency & Occupancy of    Targets: Trees with frequently    occupied targets in their fall zone present higher risks. Generally, the more often and longer a target is present, the greater the potential of impact and harm.

For more information on tree risk assessments, refer to the ISA Tree Risk Assessment Manual (2nd Edition) and ANSI A300 Tree Care Standards Part 9 (Tree Risk Assessment).

Leveraging Technology    for Assessments

Modern technology can significantly enhance the accuracy and efficiency of tree risk assessments. Here are some tools of the trade that can assist in conducting tree risk assessments for winter storm readiness:

• Drones: Unmanned aerial vehicles (UAVs) equipped with high-resolution cameras can provide a bird’s-eye view of trees to identify structural defects that may not be visible from the ground. Drone operators in the    US must obtain a Remote Pilot    Certificate through the Federal Aviation Administration (FAA) before flying a UAV.
• Tomography: This technique uses sound waves to visualize the internal condition of a tree to identify decay, cracks, or other structural weaknesses not visible externally.
• LiDAR: Light Detection and Ranging (LiDAR) technology generates detailed 3D models of tree structure to identify weaknesses and hazards that could be obscured or hidden from view. Combined with Geospatial Information System (GIS) technology, it can pinpoint nearby targets, map fall zones, and monitor tree health over time.

Wissmuller emphasized that these modern devices not only improve the accuracy of the TRA but also keep tree care workers safer.

“With drones and the like, workers can identify potential risk without putting themselves or clients in harm’s way and, while this is a fairly obvious point to make: if you can’t see the problem, you can’t fix the problem,” he stated.

Best Practices for    Winter Tree Care

Proper tree care management is key to preventing future problems. Best management practices (BMPs) for tree care are essential to ensuring trees remain healthy and resilient before, during, and after winter storms.

• Pruning: Remove dead, dying, or defective branches to reduce failure likelihood. Follow ANSI A300 Tree Care Standards Part 1 standards and avoid excessive live wood removal.
• Support Systems: Use cabling, bracing, or staking to reinforce weak structures. Adhere to ANSI A300 Clause 7 standards.
• Mulching and Aeration: Protect roots and improve soil health with proper mulching and aeration techniques.
• Watering and Fertilizing: Provide essential nutrients and moisture year-round, especially during active root growth in fall.
• Integrated Pest Management (IPM): Monitor and manage pests and diseases using selective treatments and ANSI A300 Clause 14 guidelines.
• Other Practices: Use tree guards, windbreaks, and storm-resistant species while avoiding practices that can harm trees, such as using chloride-based ice melts.

By far, pruning is one of the most effective ways to prepare trees for winter storms. Proper pruning maintains balanced canopy weight and structure and increases load-bearing capacity. When done correctly, this technique removes dead, dying, damaged, diseased, or defective branches that are more likely to fail under snow, ice, and wind.

In special circumstances, it may be necessary to remove a tree if it presents a high or extreme residual risk. Removing hazardous trees before winter strikes helps protect property from potential damage during severe weather and makes cleanup easier when it is all over.

After a winter storm, it is important to assess trees for broken branches, cracks or splits, new or worsened leans, and uprooted or downed trees.

Depending on the extent of damage, trees may require restorative pruning, cabling or bracing, or removal. Regular inspections are important to identify hidden or cumulative damage, so continue to monitor trees closely up to one year after a storm event.

Brighter Days Ahead

As we face increasingly unpredictable weather patterns and more severe winter storms, it is becoming vital to adopt best management practices for tree care. Conducting regular tree risk assessments and implementing proactive maintenance strategies can reduce the likelihood of failure and damage from storms, strengthening trees’ resilience to harsh weather conditions and ultimately protecting people and property.

By learning the lessons of today, we can better protect the trees of tomorrow from the impacts of storms.

Winter is coming. Are your trees ready for it?