SAF Tree Hazard assessment and tree risk seminars

In the wonderful oak and beech woodland of Sundsby säteri, this hands on practical workshop will focus on structural tree assessment and trees’ adaptive growth in response to decay and external forces such as wind, rooting and soil faliure. In addition delegates will be given instruction on current diagnostic equipment and techniques that assist in informing the decsion making processes of tree stability.

With many living tree relics this park will enable delegates to, at first hand, examine tree faliure, adaptive growth and Species specific macro fungi, their interaction and their wood decay properties.

This workshop, central to competent tree hazard evaluation sits between two days of QTRA registered users workshop for those that missed last years programmes. There are now 30 QTRA registered users in Sweden, this is your opportunity to join the group.

This program is an exciting possibility for arborists in Sweden to share in an enormous amount of experience of hazard tree assessment from two arborists with a long history in the profession.

The speakers

Dr David Lonsdale

David is a plant pathologist with 34 years’ postdoctoral experience in tree pathology. Since 1981, he specialised in tree decay research and in the development of procedures for tree hazard assessment and management.

On the latter subject, he has written a textbook The principles of tree hazard assessment (Lonsdale, 1999) and a Forestry Commission Practice Guide (Lonsdale, 2000). He was also the editor of the English language edition of an earlier textbook, The body language of trees:A handbook for Faliure Analysis, (Mattheck & Breloer, 1994).

Over the last 27 years he has undertaken tree hazard and risk assessments for public and private landowners; until March 2002 as an employee of the Forestry Commission (Forest Research) and subsequently as a self-employed consultant. David regularly lectures on this subject to students and tree care professionals.

Mike Ellison

Mike is principal arboricultural consultant and partner in the UK based Cheshire Woodlands Arboricultural Consultancy.

Having worked in the timber industry from 1976, Mike formed Cheshire Woodlands in 1980. The company's focus on arboricultural services developed through the eighties and is now a respected arboricultural consultancy practice specialising in the field of trees and built development and tree safety management.

In 1996, Mike developed the Quantified Tree Risk Assessment (QTRA) system principally out of frustration with the pressure from clients to provide impossible assurances that trees were safe. In 2005, a peer reviewed paper on the subject was published in the Journal of Arboriculture.

Over the past seven years, hundreds of registered users have been trained in the application of QTRA in Canada, Europe, Australia, East Asia, New Zealand and the United States.

The Quantified Tree Risk Assessment Method

Tree safety management is a matter of limiting the risk of harm from tree failure while maintaining the benefits conferred by trees. Although it may seem counter intuitive, the condition of trees should not be the first consideration. Instead, tree managers should consider first the usage of the land on which the trees stand, and in turn this will inform the process of assessing the trees.

The Quantified Tree Risk Assessment (QTRA) system applies established and accepted risk management principles to tree safety management. Firstly, the use of land upon which trees could fail is assessed and quantified, thus enabling tree managers to determine whether or not and to what degree of rigour a survey or inspection of the trees is required. Where necessary, the tree or branch is then considered in terms of both impact potential (size) and probability of failure. Values derived from the assessment of these three components are used to calculate the probability of harm.

The system moves the management of tree safety away from labelling trees as either ‘safe’ or ‘unsafe’ and thereby away from requiring definitive judgements from either tree assessors or tree managers. Instead, QTRA quantifies the risk of significant harm from tree failure in a way that enables tree managers to balance safety with tree values and operate to predetermined limits of tolerable or acceptable risk.

Where and when?

3 Jun - Quantified Tree Risk Assessment Training
4 Jun - The Ins and Outs of Tree Stability (Two Days)
6 Jun - Quantified Tree Risk Assessment Training

Course language: English.


Tree biodynamics 10th 11th 3100 kr ex moms.
QTRA 2500 kr ex moms.


Sundsby Säteri


Registration available at or