Tree biology


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Tree biology

  1. 1. Tree Biology ISA Arborist Certification Study SessionAngela Belden, Resource Forester Assistant, Missouri Department of Conservation
  2. 2. Tree Anatomy Basic structure- cells, tissues, organs, organism. Growth- ◦ Meristems  Apical meristems  Lateral meristems
  3. 3. Stem Anatomy
  4. 4. Stem Anatomy- early
  5. 5. Stem AnatomyThe cambiums- secondary meristems Cork cambium Vascular cambium
  6. 6. Stem Anatomy- cambiumsCork cambium(phellogen)--the region ofcell divisionthat forms theouter barktissues.
  7. 7. Stem Anatomy- cambiumsThe vascularcambium-- theregion of celldivision thatproduces radialgrowth.It forms the phloem& xylem.
  8. 8. Stem Anatomy- xylemThe xylemincludeseverything insidethe vascularcambium. Wood!
  9. 9. Stem Anatomy- xylemThe rings seen inmany treesrepresent onegrowth increment.Growth ringsprovide the graintexture seen inwood.
  10. 10. Stem Anatomy- xylemTracheids– cellsused forconducting water& minerals.Conifers onlyhave tracheidsand are thusconsideredsoftwoodedspecies.Hardwood specieshave vesselelements in
  11. 11. Stem Anatomy
  12. 12. Stem Anatomy- xylemFibers are cellswith heavilylignified wallsmaking them stiff.Many fibers insapwood are aliveat maturity andcan be used forstorage.
  13. 13. Stem Anatomy- xylemParenchyma–living cells usedfor storage, celldivision, anddecay defense.Axial parenchymaruns parallel withthe growth rings.
  14. 14. Stem Anatomy- xylemParenchyma–living cells usedfor storage, celldivision, anddecay defense.Rays are radialparenchymacells. Parenchyma cells give rise to adventitious tissues.
  15. 15. Stem Anatomy- barkThe bark iseverything outsidethe vascularcambium.
  16. 16. Stem Anatomy- bark: phloemPhloem tissuemakes up theinner bark.However, phloem is livingvascular tissueformed from thevascularcambium.
  17. 17. Stem Anatomy- phloemSieve tubeelements– cellsthat activelytransportcarbohydratesfrom the leavesdown the stem.Conifers havesieve cellsinstead.
  18. 18. Stem Anatomy- phloemCompanioncells–providesieve tubeelements withneededmetabolites.Conifers havealbuminous cellsinstead.
  19. 19. Leaf Anatomy
  20. 20. Autumn Leaf FallTrees thatkeep theirleaves areevergreens,trees thatlose theirleaves aredeciduous. Abscission zone– area at the base of the petiole that breaks down and causes leaf (or fruit) drop
  21. 21. Autumn Leaf FallDeclining intensity of sunlight triggers theprocesses leading up to leaf fall in autumn. Chlorophyll reduces, unmasking carotenoids. Clogged phloem veins trap sugars in the leaf and promote production of anthocyanins.
  22. 22. Root Anatomy
  23. 23. Root Anatomy
  24. 24. Root Anatomy
  25. 25. Root Anatomy
  26. 26. Root Anatomy
  27. 27. Mycorrhizae Is a symbiotic relationship- mutually beneficial- with a tree and a fungus Fungus increases surface area of roots Facilitates uptake of minerals that are otherwise unavailable Fungus gets to share the tree’s carbohydrates.
  28. 28. Photosynthesis & Respiration
  29. 29. Transpiration
  30. 30. Tree Growth & DevelopmentTree shape, height, etc, are determined by genetics, but its environment plays a part as well.
  31. 31. Tree Growth & Development Plant growth regulators are hormones that work in concert. ◦ auxin, cytokinins, gibberelins, ethylene, abscisic acid…etc. Environmental triggers ◦ Budbreak ◦ Leaf fall ◦ Seed germination ◦ Geotropism ◦ Phototropism
  32. 32. Tree DefensesChemical – to dissuade animal/insect feeding, stop pathogen infection, or help prevent rotMechanical – Thick bark, thorns, leaf hairs, thick cuticles – Shiny wax, leaf hairs – CODIT (Compartmentalization of Decay In Trees)
  33. 33. CODITCompartmentalizatio nOfDecayInTrees
  34. 34. CODIT
  35. 35. Palms- StemPalm stem-monocot Tree stem- diocot
  36. 36. Palms- Roots Root initiation zone Root mat
  37. 37. Image credits: Dr. Ed Gilman and Scott Jones, University of Florida Sharon Lilly, ISA Arborists’ Certification Study Guide Natural Resources Canada website Kathy Ripke, University of Minnesota Department of Horticultural Science Taiz and Zeiger, 1998. Plant Physiology, 2nd ed.