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Assessment of Tree Forks


Cobham, Surrey


Dr Duncan Slater

6 hours

Places Available

1 day (9:00 - 16:00 approximately) 

Exc. VAT Inc. VAT

Course Objectives:

To enable course attendees to:

-          Identify where and when junctions in trees represent a major hazard

-          Understand the main factors affecting the strength of junctions in trees

-          Describe branch junction anatomy, identifying key components of the joint

-          Categorise branch junctions into different classes of morphology related to their strength

-          Understand the relationship between natural braces and bark-included junctions

-          Categorise natural braces formed above junctions into different classes and relate this to the likelihood of junction failure

-          Describe typical causes of bark-included junctions in trees

-          Understand the main causes of the failure of junctions in trees

-          Assess the sustainability of the tree’s current branch structure

-          Specify appropriate remedial work in response to a range of junction types


This course entitles you to CEU's see this link 

Course Content:

  • Introduction to tree biomechanics 
    • Trees as adequate structures
    • The complexity of tree architecture
    • Stress notches in trees and subsequent growth responses 
    • Dynamic movement of branches in broadleaved trees
    • Trade-off in wood and trees


  • The anatomy of branch attachment 
    • A new model for branch attachment, based upon CT scanning and mechanical testing undertaken at the University of Manchester
    • Interlocking wood grain, wavy grain, whorled grain and knots Wood qualities at branch attachments 
    • Strength, density and toughness of wood formed at junctions. 
    • Mechanical testing of junctions in trees


  • Factors affecting junction strength 
    • Normally-formed junctions and diameter ratio 
    • Bark-included junction morphology and their relative strength 
    • Cracked junctions and their relative strength 
    • The role of mechano-perception (thigmomorphogenesis) in junction development


  • Junction movement under wind loading
    • Mass-damping of trees through the oscillation of branches 
    • The effects of static loading and wind loading on junctions in trees 
    • Analysis of wind movement of junctions using tilt meters
    • The effects of branch interactions and natural braces on wind movement


  • Natural braces in relation to junction assessment 
    • Different categories of natural braces formed above junctions in trees
    • Associating likelihood of failure with the presence or absence of natural braces 
    • Assessing the sustainability of natural braces
    • Disphotic zones in different tree species 
    • Species prone to branch fusion – and those that are not 
    • Current pruning practices and natural braces 
    • The need for comprehensive crown assessments prior to any pruning


  • Previous and on-going research into junctions in tree
    • Shigo’s model of branch attachment  
    • Do we need to brace every co-dominant junction? 
    • Links between tree surgery and subsequent branch failure 
    • Making use of the anatomy of tree forks in man-made materials (biomimetics) 
    • On-going research at Myerscough College


  • Risk assessments of junctions 
    • “Good forks” and “bad forks” 
    • Categorisation of the likelihood of failure of a junction based on fork morphology and natural brace class or the absence of natural bracing 
    • Formative pruning to prevent the formation of bark-included junctions 
    • Recommended remedial works to flawed and non-sustainable junctions 
    • Innovation in treatments for structural issues in trees

Module Pre-requisites:

Experience working within the arboricultural industry is desirable but new entrants will also benefit from this course in terms of learning a method to assess junctions in the aerial parts of trees. Any arboricultural professional, including arborists, local authority tree officers, arboricultural consultants, tree surveyors, tree contractors and landscape architects. It may also be useful to arboricultural students, those interested in tree risk management, tree architecture or plant biomechanics.

Terms of Cancellation or Amendments to details

  • We reserve the right to cancel courses and refund applicants if there is insufficient demand.
  • A FULL charge will be applied to any booking cancelled less than 10 working days before the event.
  • A £30 administration charge may be applied to changes made to bookings that have been received and acknowledged.

For all course bookings outside the UK and Europe, please email