Trees seem like unshakeable, elegant decorations that grace the landscape. They provide shade, serve as an excellent biological filter, and add to biodiversity. Still, with all these positive societal contributions, risk lurks when trees become diseased or structurally unsound. That's when tree risk assessment is at play.

Experienced tree professionals assess areas that could cause threats and reduce risks. Knowing the causes of tree failures allows arborists to take preventive measures to protect people and property.

Introduction to Tree Risk Assessment

A tree risk assessment is a process for identifying and evaluating the possible hazards associated with a tree. This holistic assessment looks at the tree's health, its structural integrity, and the surrounding environment. Arborists can, therefore, identify the necessary management strategies to avoid harming the tree and maintain its long-term well-being.

Factors contributing to tree risk

There are several causes of tree risk. These can be broadly classified under biological, environmental, and human causes.

Biological Factors
  • Species-specific susceptibilities: all species are vulnerable to disease, pest, and decay.
  • Decay and disease: fungal diseases, bacterial diseases, and insect infestations can weaken the inner support of a tree.
  • Weaknesses in its structure: cavities, cracks, and poor attachment of the branches can be weak for a tree.
Physical Factors
  • Soil quality: The soil is predominantly adverse, packed, or deficient in nutrients, which stresses the trees and makes them more vulnerable to disease and decay.
  • Climate and weather events include hurricanes, droughts, and storm damage that may cause breakage of trees due to the weather.
  • Pollution and urban stressors: Air pollution, soil contamination, and urbanisation often lead to poor health and short longevity in trees.
Human Factors
  • Proper planting and maintenance are crucial to enhance your outdoor space and ensure the long-term health of your trees.
  • Construction and development activities: Construction work can destroy trees' roots, further destabilising them.
  • Vandalism and intentional damage: Intentional damage by cutting or poisoning might pose significant dangers.
Visual Inspection Techniques

Today, the basis of hazard detection is still Visual Tree Inspection. The arborists carefully examine the crown trunk and root system to identify any decay diseases or structural weakness inside. To see more details in discovering what's going on inside the tree, more expensive methods like ultrasonic testing, seismograph drilling, and ground-penetrating radar enable them to look at and test the tree from top to bottom.

Risk Assessment Tools and Methods

Arborists employ various tools and techniques to assess a tree's risk level. QRA measures the risk factors and their respective probabilities regarding a tree's likelihood of failure. Qualitative risk assessment is based on the judgment of experts and visual inspections to rate risk in terms of severity and probability of failure.

Risk Mitigation of Trees

There is a strategy arborists use to prevent such identified dangers, and once the potential risks have been identified, arborists have ways to help avoid such risks. Such strategies might include some or all of the following:
  • Pruning and Trimming: Removing dead, diseased, and hazardous branches improves the tree's health and reduces its failure risk. Proper pruning and trimming can even shape the tree and give it a great structure.
  • This aspect entails using cables and braces to stabilise the tree by underpinning weakened branches and structural defects. These cable and bracing supports help trees that sometimes get damaged by storms and other inclement weather phenomena.
  • Tree Removal: In some instances, severe risks may require tree removal. Such trees may have severe decay, disease, or structural defects. Qualified individuals should always do tree removal to ensure safety and minimise impacts on the environment.
In addition to the measures above, arborists may also recommend the following measures to mitigate the potential risks of trees:
  • Soil amendment: Enhancing the soil around the tree promotes proper growth and slows down the speed of stress. This process includes adding organic matter, soil aeration, and a change in pH level.
  • Fertilisation: Fertilisers promote health and energy within a tree. However, the proper type and amount of fertiliser must be used to prevent tree damage.
  • Watering: Water is the tree's basic necessity to sustain its well-being, and during a drought period, it becomes essential. But too much water can be fatal, so deep and less frequent watering is a good solution.
  • Pest and disease control: Understanding what attracts unwanted pests is crucial for effective prevention. Frequent or regular observation of pests or diseases helps identify the problem in advance, apply a solution or measure against the problem, and thereby prevent the loss of damage caused to the tree.
In summary

These techniques help ensure that trees are safe and long-lived. Understanding factors that contribute to tree risks using effective risk assessment techniques ensures the communities' safety. Regular inspections and maintenance of trees prevent accidents and damage to properties, besides offering the benefits of these magnificent natural resources through professional tree care.