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How a Tree Grows

How a Tree Grows

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How a Tree Grows

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  1. How a Tree Grows J.G. Mexal H/R 302 Spring 2005

  2. Forestry & SocietyHow a Tree Grows- • Trees are the 2nd largest organism- Eucalyptus Sequoia • Trees are the oldest organism-bristlecone pine (5,000 yrs) Norway spruce (9,550 yrs) • They can grow: as much as 25 ft/yr as little as 25 mm/yr (1”) • They can survive: 10 ft of precipitation 10 in of precipitation • They can survive: >100oF temperatures <-50oF temperatures

  3. Alder White birch Sugar maple Oak Douglas-fir Bristlecone pine Norway spruce 25 yrs 50 yrs 300 yrs >500 yrs >700 yrs >2,000 yrs >9,000 yrs Trees live a long time!

  4. Forestry & SocietyHow a Tree Grows- • What does your tree look like? • A 100 ft tree weighs about 4,000 lbs • Has > 200,000 leaves (~120 lbs) • Will shed 3,600 lbs of leaves in a lifetime • Produce >5,000 seeds/yr • Have 1,300 lbs of roots • Require • 8,000 lbs of CO2 • 2,900 lbs of H2O for Ps, and 5,000,000 lbs for Ts • Generate over 8,000 lbs O2

  5. Source: Ed Gilman, IFAS

  6. Trees in the forest grow with one trunk, and codominant stems toward the top of the tree Source: Ed Gilman, IFAS

  7. Forestry & SocietyComparison between forest tree and landscape tree Source: Ed Gilman, IFAS

  8. Genetic Information Environmental Conditions Physiological Processes Tree Growth Factors affecting tree growth

  9. Bark Cambium Earlywood Heartwood Latewood Sapwood Forestry & SocietyHow a Tree Grows-Functions • Seed- reproduction • Leaves- photosynthesis (carbon capture) • Roots- water & nutrient uptake • Bark- protection • Cambium/buds-growth • Xylem- water transport (up) [dead] • Phloem- carbohydrate transport (down)

  10. How a Tree Grows

  11. Our secondary growth model: A typical hardwood tree in cross section (transverse surface). What can you identify? Source: Ed Gilman, IFAS

  12. The Bark: The bark is everything outside the vascular cambium. As you can see, there is a lot going on in the bark. Source: Ed Gilman, IFAS

  13. The Bark: periderm: Periderms form the outer bark. They are subdivided further. Source: Ed Gilman, IFAS

  14. The Bark: periderm: phellogen (cork cambium): The phellogen is the region of cell division that forms the periderm tissues. Phellogen development influences bark appearance. Source: Ed Gilman, IFAS

  15. The Bark: periderm: phellem (cork): Phellem replaces the epidermis as the tree increases in girth. Photosynthesis can take place in some trees both through the phellem and in fissures. Source: Ed Gilman, IFAS

  16. The Bark: periderm: phelloderm: Phelloderm is active parenchyma tissue. Parenchyma cells can be used for storage, photosynthesis, defense, and even cell division! Source: Ed Gilman, IFAS

  17. The Bark: phloem: Phloem tissue makes up the inner bark. However, it is vascular tissue formed from the vascular cambium. Source: Ed Gilman, IFAS

  18. The Bark: phloem: sieve tube elements: Sieve tube elements actively transport photosynthates down the stem. Conifers have sieve cells instead. Source: Ed Gilman, IFAS

  19. The Bark: phloem: companion cells: Companion cells provide sieve tube elements with needed metabolites. Conifers have albuminous cells instead. Source: Ed Gilman, IFAS

  20. The cambium: The cambium is the primary meristem producing radial growth. It forms the phloem & xylem. Source: Ed Gilman, IFAS

  21. The Xylem (wood): The xylem includes everything inside the vascular cambium. Source: Ed Gilman, IFAS

  22. The Xylem: a growth increment (ring): The rings seen in many trees represent one growth increment. Growth rings provide the texture seen in wood. Source: Ed Gilman, IFAS

  23. The Xylem: vessel elements: Hardwood species have vessel elements in addition to trachieds. Notice their location in the growth rings of this tree Source: Ed Gilman, IFAS

  24. The Xylem: fibers: Fibers are cells with heavily lignified walls making them stiff. Many fibers in sapwood are alive at maturity and can be used for storage. Source: Ed Gilman, IFAS

  25. The Xylem: axial parenchyma: Axial parenchyma is living tissue! Remember that parenchyma cells can be used for storage and cell division. Source: Ed Gilman, IFAS

  26. The Xylem: rays (multiserrate & uniserrate): Rays are radial parenchyma cells. Parenchyma cells give rise to adventitious tissues. Source: Ed Gilman, IFAS

  27. Forestry & SocietyHow a Tree Grows/Diffuse vs Ring Porous Silver Maple White Oak Ring Porous Diffuse Porous 50X

  28. Forestry & SocietyHow a Tree Grows-Idealized Leaves leaves A tree can produce 200,000 leaves/yr fruit Fruit Annual rings Taproot Lateral root

  29. Woody Stem Structure

  30. Shoot Growth

  31. Forestry & SocietyShoot Growth in Eastern White Pine Terminal growth = 44 cm Lateral branch = 26 cm 2o lateral = 12 cm Lateral branch = 19 cm Lateral branch = 14 cm 2o lateral = 10 cm 3o lateral = 6 cm 2o lateral = 10 cm

  32. Biomass Partitioning/Nelda Methany 2005 Percent 100 90% Wood 35% 35% 30% Leaves/Roots 5% 5% Fine Roots 3 7 20 55 Time (yrs)

  33. Forestry & SocietyHow a Tree Grows • Growing regions or meristems • Buds- height, flowers, leaves, (roots) • Cambium- diameter • Cork cambium - bark • Factors • Temperature • Light • Water Tropics vs Boreal

  34. Dry tropical forest Desert Tropical forest Where a tree grows!! 20” 80” 140” oF 86 59 32

  35. Forestry & SocietyUrban ForestryCO2 capture Basic Photosynthetic Reaction • CO2 + H2O CH2O + O2 • 1.47 lb 0.60 lb 1.00 lb 1.07 lb λ

  36. clear day overcast day Forestry & SocietyHow a Tree Grows/ Kozlowski & Pallardy 1999

  37. Forestry & SocietyHow a Tree Grows • Most forests are regenerated sexually • seeds are required • exceptions: aspen, oak, eucalyptus • Environmental factors: • light (forest gap) • moisture (mineral soil) • temperature (dormancy & germination)

  38. Forestry & SocietyHow a Tree Grows - Piñon • Flower primordia (buds) form in fall (yr-1) • Flowers develop in spring (yr-2) • Pollination occurs • Overwinter • Fertilization occurs in spring (yr-3) • Growth of cone • Maturation of cone with seeds in fall • Total time elapsed >24 mo. Drought

  39. Pine life cycle

  40. Forestry & SocietyHow a Tree Grows/Reproductive Cycle of Pinus contorta(Owens & Molder 1984)

  41. Forestry & SocietyHow a Tree Grows-female cones Pinus elliotii (slash pine) maturation fertilization pollination 24 mo. 12 mo. 1 mo.

  42. Forestry and SocietyPinus eldarica cone Rachis Viable seed Empty seed Bract

  43. Forestry and SocietyPine seed size variation wing Pinus pinea (Italian stone pine) Pinus nigra (Japanese black pine)

  44. Seed is dispersed Overwinters (dormant) Germinates Growth commences 10,000,000/ac 4,000,000/ac 4,000/ac @ 25 yrs 100/ac @ 100 yrs Forestry & SocietyHow a Tree Grows-Germination Nothofagus in Chile 0.001%

  45. Ponderosa pine seed rain following harvest-CO /WJAF 21(1):19:06 Logged ’80-’81 winter Seeds/m2 Seedlings/m2 ~48% of seed consumed by animals regardless of year Year

  46. Dendrochronology

  47. Forestry & SocietyXylem production- earlywood vs latewood Phloem 3,4 = Latewood cells 1,2 = Developing xylem cells 5 = Earlywood cells L = Preceeding year

  48. Forestry & SocietySilviculture/Response to Thinning Juniper/NM False rings Wider rings 10 mm Competition

  49. Earlywood Eruption occurs June 8, 1783 Latewood No Latewood, indicating very early onset of winter Forestry & SocietyDendrochronology/Skaptar Jokull Volcano eruption in Iceland causes ‘the summer that wasn’t’ in western Alaska. (http://abcnews.go.com/sections/science/DyeHard/dyehard.html)

  50. Review Questions • Define: xylem, conifer, phloem, hardwood, cambium, softwood, cord, evergreen, board foot, deciduous, basal area, MAI, CAI, PAI, closed forest, earlywood (spring wood), latewood (summer wood), dendrochronology, false ring • What environmental factors affect seed production germination? Why does piñon have good seed crops every 4-5 years? • Describe the basic process of photosynthesis. • Why do trees produce so many seed, yet so few germinate?