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Leaving The Cave Of Ancient Arboriculture(2)
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Leaving The Cave Of Ancient Arboriculture(2)


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  • 1. Leaving the Cave of Ancient Arboriculture : a look at common tree myths in Hawai‘i Undergraduate Seminar Fall 2008
  • 2. 5 Objectives or “Hopes”
    • To have a better understanding of the tree as a living, dynamic organism
    • To understand the basic response and defense mechanisms of trees.
    • To understand why some treatments cause harm to trees.
    • To learn to recognize common ‘myths’ about trees and to see the trees for what they are.
    • Exposure to the world of arboriculture.
  • 3. So, what IS the point? ~~~ learn to see trees for what they are ~~~ The tree which moves some to tears of joy is in the eyes of others only a green thing that stands in the way.   Some see Nature all ridicule and deformity, and some scarce see Nature at all.   But to the eyes of the man of imagination, Nature is Imagination itself. -  William Blake, 1799, The Letters  
  • 4.
    • _______________________________
    Trees and Quality of Living ▪ Research shows trees reduce noise pollution by up to 50% (Reethof and McDaniel, 1978) ▪ Increased property values (Anderson and Cordell, 1985) ▪ Stronger sense of community (Dwyer et al, 1991) ▪ Reduction of greenhouse gas emissions , increased air quality (Rowntree and Nowak, 1991)
  • 5.
    • “ trees are great to climb ; trees give us shade ; dogs love trees for obvious reasons; trees are a necessary ingredient for making a tree house .
    • … and where else would cats get stuck ? ”
    Fiona Day, 4 th grade
  • 6. ___________________________ Origin: 1820–30; < LL mȳthos < Gk mŷthos story, word myth [ miths ] (plural myths ) 1.  ancient story:  a traditional story about heroes or supernatural beings, often attempting to explain the origins of natural phenomena or aspects of human behavior 2.  idealized conception:  a set of often idealized or glamorized ideas and stories surrounding a particular phenomenon, concept, or famous person the myth of the new man 3.  myths collectively:  myths considered as a group or as a genre 4.  false belief:  a belief or notion based more on tradition or convenience than on facts.
  • 7. half-truth , haf-truth(n) A statement that mingles truth and falsehood.
  • 8. Tree Myths We have many ideas about trees. Sometimes they work, …. and sometimes they don’t .                                        What kind of times are they, when                                        A talk about trees is almost a crime                                        Because it implies silence about so many horrors?                                                                     -    Bertolt Brecht, To Those Born Later
  • 9. the half-truth : pruning
    • pruning is the removal of plant parts – usually shoots and branches, but sometimes buds, roots, and even flowers and fruits
    • pruning can enhance plant appearance and safeguard plant health and well-being.
    • pruning can control plant size (if done properly)
    • pruning can increase the health and appearance of trees.
    • pruning can influence flowering, fruiting, and vigor.
    “ a good doctor understands dose !”
  • 10. ___________________________
    • 1. The internodal removal of a leader trunk or parent branch.
    topping [top-ing] __________________ heading [hed-ing]
    • Cutting a currently growing or one-year old
    • shoot back to a bud.
    • Cutting an older branch or stem back to a
    • stub or tiny twig.
    … defined
  • 11. Topping stresses trees *Often anywhere from 50 – 100% of photosynthetic leaf area is removed during a single topping treatment. *Topping often initiates expansive columns of decay in both the above ground (branches and trunk), and below ground (roots) portion of the tree (Shigo, 1981).
  • 12. CODIT Compartmentalization of Decay In Trees
  • 13. CODIT – C ompartmentalization O f D ecay I n T rees
    • Wall 1 is formed by the physical plugging of xylem (tracheids and vessel elements) above and below the injury (two walls). Wall 1 may or may not be present at the time of the injury. Wall 1 prevents the spread of decay upward and downward in the trunk of the tree.
    Wall 1 Wall 1 *weakest barrier zone (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 14. CODIT – Compartmentalization Of Decay In Trees Wall 2 is already present at the time of injury. Wall 2 consists of the annual rings of xylem. This protection zone is responsible for preventing the inward spread of decay. Wall 2 *trees don’t heal they compartmentalize (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 15.
    • Wall 3 is also already present at the time of injury. Wall 3 consists of the parenchyma rays located on either side of the injury (two walls). Wall 3 prevents the lateral spread of decay in the tree.
    CODIT – Compartmentalization Of Decay In Trees Wall 3 Wall 3 (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 16.
    • Wall 4 consists of the new xylem that is produced by the vascular cambium after wounding to prevent the outward spread of decay.
    CODIT – Compartmentalization Of Decay In Trees Wall 4 Wall 4 (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 17. Callus formation & Compartmentalization
  • 18. We often say wounds that have strong callus formation are well “ healed ” more myths more confusion A tree may appear well ‘ healed ’ from the outside, … but in fact extensive decay may exist internally… (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 19. Closure and Compartmentalization are 2 different processes After 17 years, the wound did not close. Very little decay spread inward.
  • 20. Tree Anatomy – “Branch Attachment”
    • How are branches so strong ? They are not structurally connected to the trunk!
    (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 21. Tree Anatomy – “Branch Attachment” ____________________________________________________________ Darker colored tissues represent branch tissue. Lighter colored tissues represent trunk tissue. Represents 3 growth rings pulled apart (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 22. Tree Anatomy – “Branch Attachment” ____________________________________________________________ Tissues turn abruptly at the branch base. As the tissues develop downwards, they do mix (intertwine) with the trunk tissues. This area where the tissues ‘mix’ is the only area where the branch and trunk are structurally connected. (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 23. Tree Anatomy – “Branch Attachment” ____________________________________________________________ A series of steps… _____________________________
    • Branch tissues slow their growth rate
    • Trunk tissues increase growth rate and begin to grow over branch collar
    • Trunk tissues form a collar over the branch collar
    • These steps repeat themselves, forming an overlapping “ball and socket” type connection.
    (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 24. Tree Anatomy – “Branch Attachment” ____________________________________________________________ Nature’s engineering…. This image shows a longitudinal dissection, illustrating branch and trunk tissues overlapping (Photo taken from “A New Tree Biology” Shigo, Alex)
  • 25. “ Epicormic Branches and Failure” ____________________________________________________________ Epicormic - “upon the bark” Two types: 1. From dormant buds that are carried along through the wood and eventually may develop to form a branch (Shigo, 1991)
  • 26. “ Epicormic Branches and Failure” ____________________________________________________________ Epicormic - “upon the bark” Two types: 2. Adventitious buds that form anew, de novo, within the cambium, usually after some injury (Shigo, 1991)
  • 27. “ Epicormic Branches and Failure” ____________________________________________________________ Epicormic - “upon the bark” Much weaker attachment The latter type of epicormic has a much weaker attachment point, very similar to included bark. Attachments are structurally undermined by pockets of decay where the new branch originates from after ‘topping’. Illustrates V shaped union common with included bark and adventitious growth after topping. Illustrates adventitious shoots after topping. Notice narrow angle of attachment and decay in parent.
  • 28. “ Epicormic Branches and Failure” ____________________________________________________________ Demystifying Included Bark Branch bark ridge is bark tissue that gets pushed upward within the branch-trunk crotch. A strong branch-trunk union is evident by the BBR pushing ‘upwards’. It’s important to understand included bark to understand the type of connection that often develops after topping!
  • 29. “ Epicormic Branches and Failure” ____________________________________________________________ Demystifying Included Bark Tissues have turned ‘inward’, evidence of a weak union
    • The vascular cambium turns ‘inward’ within the branch-trunk crotch.
    • The branch bark ridge also turns inward
    • Trunk cylinder (collar) and branch cylinder (collar) both expand
    • Inturned cambium becomes a wedge between the two cylinders.
  • 30. Solutions & options __________________________________________________________________ Cabling and Bracing Pruning Removal
  • 31. Solutions & options
    • crown reduction - Reducing the height or spread of a tree by pruning back the leaders and branch terminals to lateral branches that are large enough to assume the terminal roles (at least one-third the diameter of the cut stem).
  • 32. Solutions & options
    • Remove and Replant
    __________________________________________________________________ Select the Right Tree for the Right Place!
  • 33. The Bonsai Myth
  • 34. The Bonsai Myth
    • Lion tailing – practice of removing the inner foliage and branches, leaving growth at the outer one-third to one-fourth of the canopy.
  • 35. The Bonsai Myth
    • Rule of Thumb –
    • Do not remove more than 1/3 of live canopy at one time.
  • 36. The Bonsai Myth Lion tailing reduces branch taper, leading to higher rates of failure. (Matheny & Clark, 1994) Greatly reduces photosynthetic surface area, often leading to stressed conditions. Increases center of pressure height Permanently alters overall structure of canopy by removing interior growth. Leaves much fewer options for pruning.
  • 37. Solutions & options
    • Thinning - the selective removal of branches to increase light penetration and air movement through the crown. Thinning opens the foliage of a tree, reduces weight on heavy limbs, and helps retain the tree’s natural shape.
  • 38. Industry Standards
    • ANSI A300 - The standards dictate the requirements and recommendations of the tree care industry for satisfactory performance of tree care maintenance.
    Operations Construction Lightning Pruning
  • 39. Certification
  • 40. Resources International Society of Arboriculture ( Trees are Good ( Aloha Arborist Association (
  • 41. References
    • Anderson, L.M. and H.K. Cordell. 1985. Residential property values improve by landscaping with trees. S.J. Appl. For: 9:162-166
    • Clark, J. and Matheny, N. 1994. A Photographic Guide to the Evaluation of Hazard Trees in Urban Areas. Hortscience Inc.
    • Dwyer, J.F., Schroeder H.W., and P.H. Gobster. 1991. The significance of urban trees and forests: Towards a deeper understanding of values. J. Arboric. 17:276-284
    • Reefhof G., and O.H. McDaniel. 1978. Acoustics and the Urban Forest . Proceedings of the National Urban Forestry Conference. USDA Forest Service. State University of New York College of Environmental Science and Forestry, Syracuse, NY.
    • Rowntree, R.A. and D.J. Nowak. 1991 . Quantifying the role of urban forests in removing atmospheric carbon dioxide. J. Arboric. 17:269-275
    • Shigo, Alex. 1991. A New Tree Biology. Shigo and Trees, Associates.
    • Shigo, Alex. 1984. Modern Arboriculture. Shigo and Trees, Associates.
  • 42. 2008 ISA Conference – St. Louis, MO
  • 43. 2008 ISA Conference – St. Louis, MO Dr. Steve Sillett’s research at Humboldt State University, California
  • 44. 2008 ISA Conference – St. Louis, MO