Current opinion within the UK arboricultural industry on the management of bark-included junctions in trees

ABSTRACT

Sharing practice amongst arboriculturists is potentially a very valuable process for identifying commonalities in approaches to tree management and to identify where further research is needed. In the particular case of bark-included junctions (a common structural flaw occurring in a wide range of tree species), a questionnaire was launched at eleven UK-based training workshops in 2016. The questionnaire covered theories and practices in relation to how bark-included junctions and natural braces are managed in the UK. The questionnaire received 348 responses, with a total of 6,635 years of arboricultural experience. Respondents consistently identified that normally formed branch junctions are rarely seen to fail but bark-included junctions do so frequently; that failure of bark-included junctions is more commonly caused by tension over torsion; and that most UK practitioners prefer to prune to lessen the likelihood of failure of a bark-included junction rather than installing an artificial brace. Responses highlighted areas of uncertainty, including the main cause of bark-inclusion failures and the importance of natural braces to the structural integrity of trees. It also highlighted the need for further practical experimentation upon bark-included junctions at various stages of bulging and is considered a key research area to better inform risk management decisions.

KEYWORDS:

• Bark inclusions
• branch attachment
• branch junction
• natural braces
• risk management

Acknowledgments

The author wishes to thank all 348 people who contributed to this research by completing the questionnaire in the summer of 2016 for sharing their thoughts and arboricultural practice with many others.

Disclosure statement

No potential conflict of interest was reported by the author.

Additional information

Notes on contributors

Duncan Slater

Duncan Slater is a senior lecturer in arboriculture at Myerscough College, Lancashire, a professional member of the Arboricultural Association and a chartered forester. He holds a Bachelor of Science in Forestry, a Bachelor of Arts Honours in Philosophy, a Master’s degree in Resource Management, a Master’s degree in Education and a PhD in Plant Sciences. His research interests are in the areas of tree biomechanics, tree pathology, tree nursery techniques and urban forestry.