Tree Biomechanics for Practical Arboriculture Auckland Workshop
21 February 2020
Auckland University of Technology
55 Wellesley Street East, Auckland, NZ
21 Feb 2020
Have you ever wondered why trees fail?
Or given any thought to the effect your latest pruning operation will have on tree structural integrity?
Trees are self-optimising structures, and human interventions such as construction damage to root systems, or poor crown pruning, can disrupt the balance in a tree’s biomechanical characteristics and ultimately have dire consequences, such as complete tree failure.
NZ Arb are proud to announce that we are running two biomechanics workshops in February hosted by world-leading experts in the field. Dr Andrew Koeser (University of Florida) and Dr Jason “Jake” Miesbauer (Morton Arboretum)
Koeser and Meisbauer will deliver two one-day workshops in New Zealand in February. A must-attend workshop for anyone involved in tree management decisions. Groundies, climbers, consultants and tree managers are encouraged to attend. This opportunity won’t come around again. Tea, coffee and snacks will be provided but you will need to bring or buy your own lunch. Workshops are limited at 50 attendees.
9:00 - 9:45
Introduction to Tree Biomechanics
Trees are long-lived perennial plants that use their size to their advantage when competing with other plants for light and belowground resources. As they grow, they must constantly adapt to the various forces that act on them. This session serves as a primer on tree biomechanics - exploring aspects of forces that act on trees and how they react and adapt to those forces.
9:45 - 10:15
Why Trees Fail Part 1: Belowground
Roots are both an anchor and an intimate connection to the surrounding soil. Unfortunately, given their hidden nature, roots are often a minor consideration when identifying planting spaces, siting construction activities, and assessing tree risk. In this session, we will summarise existing research regarding the impact of arboricultural activities on whole-tree stability.
10:15 - 10:45
Why Trees Fail Part 2: Aboveground
Trees are built to withstand the forces they have evolved to endure. Given enough time, however, all trees will develop structural defects. Many defects pose negligible risk to the surrounding environment or to the tree itself. On the other end of the spectrum, severe defects can lead to catastrophic failure. While many defects such as large cavities or broken branches are easy to recognise, others can be more subtle. This presentation will discuss tree failure within the natural and urban context. We will also explore patterns that can be discerned with regard to species, defects, and cultural management effort.
11:00 - 12:00
Attendees will be exposed to the three main elements of risk assessment (i.e., likelihood of impact, likelihood of failure, and consequences of impact) - with an emphasis on failure potential.
12:45 - 13:30
Pruning Trees to reduce likelihood of failure
Tree pruning is one of the most common practices employed by tree care professionals. Proper pruning can improve tree structure, remove or mitigate defects, and help to enhance tree health and aesthetics. It is important to keep in mind, however, that each pruning cut is an injury that the tree must respond to, and if done improperly can be counterproductive. This presentation will help the audience better understand how proper tree pruning can achieve targeted goals of reducing the likelihood of trees being damaged in storms.
13:30 - 15:00
In this hands-on session, the instructors will walk participants through a series of potential pruning prescriptions for trees at various stages of growth (e.g., newly planted to senescing). We will also look at trees with various defects and discuss management options for how those defects can be mitigated.
15:00 - 15:30
After the storm: Crown restoration pruning of storm damaged trees
Storm damage is a common issue faced by urban tree managers. Sometimes trees are severely damaged and need to be removed. Many more, however, receive moderate levels of damage and can be saved. When tree branches get damaged during storms they typically respond through the production of sprouting branches. Sprouts are a critical component in replacing the tree’s photosynthetic capacity. As the new branches grow and develop, restoration pruning becomes an important process to help improve the structural integrity of the tree crown. This presentation will cover the process of managing trees that have been damaged in storms, from first response after the storm, through the crown restoration process.
15:30 - 16:30
Can Anyone Actually Predict Tree Failure?
Tree risk assessment is a very human endeavour. Research has shown that experiences and personal biases can significantly impact risk assessments. Does this mean risk assessment is flawed? How accurate can our assessments get? This section will highlight findings from recent research regarding the accuracy of estimates of likelihood of failure as related to overall tree risk.