1. Leaving the Cave of Ancient Arboriculture : a look at common tree myths in Hawai‘i Undergraduate Seminar Fall 2008
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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
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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.
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
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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).
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)
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.
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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)
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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!
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30. Solutions & options __________________________________________________________________ Cabling and Bracing Pruning Removal
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.
40. Resources International Society of Arboriculture (www.isa-arbor.com) Trees are Good (www.treesaregood.com) Aloha Arborist Association (www.alohaarborist.com)