Disclaimer: The views and opinions expressed in this article are those of the author and do not necessarily reflect the views of the Arboricultural Association.

Share this story


#ARBatwork #ArbMatters #PledgeLessPlastic & 12 Faces of Arb 1987 storm 2018 3ATC 3ATC UK Open 50th annual AA AA award AA Awards Aboricultural Association Accident accreditation advice AFL aftercare AGM Agrilus Biguttatus aid air quality Alert Alex Kirkley All Party Parliamentary Group on Horticulture amenity Amenity Conference Ancient Tree Forum Annual Awards app APPGHG apprentice apprenticeship Apprenticeships Approved Approved Contractors ARB ARB Approved Contractor ARB Approved Contractors ARB at work ARB Magazine ARB Show arb training ArbAC ArbCamp Arboricultural Association Arboriculture arborists Arbsafe Ash ash dieback Asian Hornet Assessments atf Australia Autumn Review award Awards Barcham Trees Bark Beetle Bartlett Bartlett Tree Experts bats beetle beyond ism Bill Matthews biochar biodiversity biosecurity branch Branches brand Brexit bs5837 bursary business Call for papers Campout Canker stain of plane carbon Cavanagh CCS Cellular Confinement Systems CEnv Ceratocystis Ceratocystis platani chainsaw chalara charity Charles charter Charter for Trees chelsea Chelsea Flower Show Claus Mattheck climate climate change climber climbing Colleges committees competition competiton conference Confor conifers conservation Consultant consultation Contractor Coroner Council Countryside Stewardship Course for beginners cross industry news Crown & Canopy Cryphonectria parasitica Cumbria DART Date for your diary deadwood death defra Design Devon disease document donate dothistroma draft EAC East Anglia ecology Economic Report economy Ecotricity education Electricity England English Elm environment environmental EPF equipment Europe European Arboricultural Council European Wood Pastures exeter Exhibitors Fatal Fatality felling Fellow Fera Field Trip Fine flood flooding Forest Research forestry Forestry Commission forests FSC Fund4Trees funding fundraiser fungal fungi Futurebuild gardening GDPR Geocells Gold Medal Gov.uk government grant grants Green Brexit Green Infrastructure Green Infratructure guidance Guidance Note 2 guides Hazard Tree Health Helliwell Help Henry Kuppen History Honey Brothers Horse Chestnut horticulture horticulturists HortWeek housing HRH HRH Prince Charles HS2 HSE ICF identification industry industry skills Infographic InfraGreen Inspiration Insurance Intermediate Tree Inspection International Urban Forestry Congress Investigating Tree Archaeology Conference Ips typographus Irma irrigation ISA iso i-Tree IUFC Job job opportunity judgement JustGiving Karabiner Kew land-based Landscape Institute Landscape Show landscaping Lantra law Leaf Minor Lectures legal legislation Liability licence London longevity LTOA Magazine maple Mayor of London MBE Melbourne Member Benefit Membership mentor Midlands moth' NASA National Geographic National Tree Safety Group National Tree Week NATO New Year’s Honours News nominations Northern Northumberland notification NTIS NTOA NTOC NTSG oak 'oak Oak Processionary Moth Oak-boring Beetle obituary Observatree occupation opm Padua parks parliament Perennial Pests and Diseases petition photo Phytophthora planning Planning Law planting Plumpton College policy poll Power Preston Twins Prince Charles Prince of Wales processionary prosecution Protect and Survive protected tree protection Qualifications Quotatis ramorum RC Reg Harris Registered Registered Consultant Registered Consultants Rememberance Day renewal Report Rescue research Research grant Resilience response results retrenchment review RFS rhs RHS Chelsea Flower Show Ride for Research Ride4Research rigging Rodney Helliwell rogue tree surgeons RSFS Safety Safety Bulletin Saftey Scotland Scotland Branch Scottish Branch SDG Accord security seminars Share Sheffield Show Sierra Leone Site Guidance skills SocEnv soil soils South East South West SRWP staff statement Stationary Rope statutory STIHL strategy student Student Conference survey Sustainable Soils Alliance Sweet Chestnut sweet chestnut blight T Levels Tatarian maple TDAG technical guide Technical Guides Technical Officers Ted Green tender Thames & Chiltern The Arboricultural Association The Woodland Trust Thinking Arbs Thinking Arbs Day Timbersports Tools top-handled chainsaws,Elcoat, TPBE4 TPO Trading Standards trailblazer training transport Tree Tree Champion Tree Council Tree Fayre Tree Health Tree Inspection tree loss tree management Tree of the year Tree Officer Tree officers Tree Protection tree register tree species Tree Surgeon Tree Surgeons Tree Week Treeconomics tree-felling TreeRadar trees trees' Trees & Society Trees, People and the Built Environment trust' trustee Trustees TrustMark UAG Uitlity UK favourite ukas UKWAS urban urban forest Urban Forestry Urban Tree Cover urban trees Utility Arboriculture Group vacancy VETcert veteran trees video Videos volunteer VTA WAC Wales watering solutions webinars website Western Westonbirt Wharton Witley Women Women in Arb women in arboriculture woodland woodland trust woods World Environment Day Xylella young young arborists Young People’s Breakfast Event zoo

Assessment of Tree Fork Workshops announced

Last Updated:  10/10/2016

Do you know how a branch is attached to the trunk of a tree?

If not, don’t you think you should?


Branch Bark Ridge

Recent published research from Myerscough College and the University of Manchester has provided us with a clearer picture of the anatomy of junctions in trees. For the Arboricultural Association, lead research Dr. Duncan Slater will be providing a number of Fork Workshops around the UK this summer and autumn, as it is felt that this is a very important area of technical knowledge for our members to get to grips with.

Junctions in trees vary in their size and anatomy, but typically have a number of features in common. The most important anatomical feature for strengthening a junction is the presence of tortuous, twisted and dense wood grain down the central seam of the join between the two conjoined limbs – the location of which can be seen externally by the presence of the branch bark ridge.

Stem wood of hazel (Corylus avellana L.) in cross-sectional view (CT scan image courtesty of MXIF)

Stem wood of hazel (Corylus avellana L.) in cross-sectional view (CT scan image courtesy of MXIF)

Twisted wood formed at the centre of the branch bark ridge in hazel, in comparison (MXIF, 2012)

Twisted wood formed at the centre of the branch bark ridge in hazel, in comparison (MXIF, 2012)

Whirled wood grain pattern forming an interlock between two limbs in a mature oak tree

Whirled wood grain pattern forming an interlock between two limbs in a mature oak tree

In most junctions, this centrally-placed wood grain forms an interlocking pattern – so it is necessary to snap wood fibres along their length or to extract them from adjacent wood in order to break the junction. You can see this feature by eye in many tree species if you strip the bark off around a branch attachment, and many of you may well have experienced that this twisted and dense material is much more difficult to split when firewooding.

Perhaps, though, you have never really thought of this as the way in which branches of trees are ‘stitched together’

Where a small branch joins a larger stem, the older part of the branch becomes occluded (‘swallowed up’) by the tree’s trunk to form a knot. Where two branches of roughly equal size join in the crown of a tree, forming a ‘fork’, there is no supporting knot, and the interlocking wood grain patterns are essential to stabilise these joins.

Interlocking grain and knot formation in a branch-to-stem attachment

Interlocking grain and knot formation in a branch-to-stem attachment

Interlocking grain in a branch-to-branch attachment (aka ‘a tree fork’)

Interlocking grain in a branch-to-branch attachment (aka ‘a tree fork’)

Where bark is included into the junction, this interlocking and tortuous wood grain can be absent, making such a branch attachment substantially weaker.

Bifurcation with wide-mouthed bark inclusion, typically 42%25 weaker than normally-formed bifurcations.

A. Bifurcation with wide-mouthed bark inclusion, typically 42% weaker than normally-formed bifurcations.

Cup-shaped bifurcation with bark being occluded by xylem growth, typically 21%25 weaker than normally-formed bifurcation

B. Cup-shaped bifurcation with bark being occluded by xylem growth, typically 21% weaker than normally-formed bifurcation.

At our “Assessment of Tree Forks” workshops, Dr. Slater will provide guidance on how to professionally assess junctions in trees for their safety, he will supply many images and examples from his research showing the anatomy of junctions and he will be reporting on his most recent research work as to how bark-included junctions are formed and how they are associated with ‘natural braces’. This one day course will provide delegates with very valuable new knowledge on the very recent research in this area, as well as introducing a framework for predicting the failure of suspect bark-included junctions.

Date & Venues

Branch supported workshop dates and locations:

Click a date to book.

28 November
Wokingham, Surrey
2 December
Preston, Lancashire