Crown Aging, Thinning And Other Crown Altering Treatments
Trees age just as all organisms do. Treatments must change as trees age.
As a tree ages the crown changes. A maturing tree will have three crowns. Generally speaking - You can feel a difference between the texture of the three areas. They function under different conditions. When the temperature is above 40 degrees f. photosynthesis begins. Here is the theory - When the temperature is around 40 degrees f. in a maturing tree #3 functions. As the temperature raises toward 70 degrees f. the #2 crown functions (GENERALLY SPEAKING). When the temperature is around 90 degrees f. the #1 crown functions.
It was in the past, a common treatment was to "thin" the tree by removing the inner crown or crowns. It was thought, this would let the wind through without wind injury. Actually a palm tree stands tall in the wind, by the fronds throwing the wind off guard. The same with the inner crowns of angiosperms and gymnosperms. So this is a treatment of the past, i.e., thinning and removing crowns #1 and #2. Not suggesting its not still done, but not an acceptable treatment in MODERN ARBORICULTURE.
Knowing The Limits.
When light is low, crown 3 works mostly. When light is high crown 1 works mostly. Crow 2 is intermediate. Dr. Shigo suggested to learn about limits, dose, timing, and methods.
Trees have three basic crowns. When pruning, do not eliminate one of the crowns or low energy reserves will lead to low defense. E.g., thinning would remove crown 1 and maybe 2.
See Ė DVDís by ALEX L. SHIGO
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