Svenska Trädföreningen

Fork Assessment Workshops for Arboricult

Fork Assessment Workshops for Arboriculture

Greninfästningar och invuxen bark är något som många känner sig mycket osäkra på, när är egentligen en greninfästning stark och när behöver olika åtgärder sättas in?

De senaste tio åren har forskningen gjort stora framsteg och under denna endagarsworkshop kommer Duncan Slater föreläsa och visa hur olika typer av infästningar ser ut och hur de kan bedömas ut ett risk– och åtgärdsperspektiv.

Under kursen får du både ta del av föreläsningar och förevisningar utomhus.

Nedan finns kursmålen och detaljerad information om kursinnehållet:

 

To enable course members 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 a tree’s current branch structure
  • Specify appropriate remedial work in response to a range of junction types

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 trees

  • 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