Climate Change & Variability
Lab Related

Tree Basics

Conifer (Gymnosperms)

Angiosperms (broadleaf)

  • develop flowers
  • covered seeds
    • nut
    • apple
    • cherry


Tree circulatory or vascular system

  • Xylem is the innermost layer of the three circulatory tissues.
    • provides support structure
    • provides part of circulatory system
    • made almost entirely of dead cells
    • thin outer ring is alive
    • cells are like thin tubes stacked on each other
    • transport water and minerals from soil to leaves.
    • living xylem works for one year and then dies.
  • Cambium is the thin layer found between the xylem and phloem.
    • has cells that can produce xylem and phloem.
    • growth varies with
      • temperature,
      • amount of moisture, and
      • amount of sunlight.
  • Phloem is the outermost layer, found outside the cambium, just inside the protective bark.
    • has tube-like cells for transport
    • transport sap that contains sugars from leaves to rest of plant
  • Bark protects the tree
    • produced from cork cambrium





Preferred Tree Species Characteristics for Dendrochonology 

  • extensive range
  • ring uniformity
  • rings are well-defined


Basics of Ring Formation

  • Conifer Tree Ring
    • earlywood: appears light in color
      • cells have thin walls, large diameter
    • latewood: appears dark in color
      • cells have thick walls, small diameter


  • Angiosperm Tree Ring

    • earlywood: cells have large diameter vessels

    • latewood: cells have small diameter vessels



Douglas Fir Example





 Oxygen Isotope Ration Analysis


Atomic number

  • Number of protons in nucleus (O8, Na11, Fe26)
  • Uniquely identifies a chemical element

Mass number

  • Number of protons and neutrons in nucleus
  • Most mass is in protons and neutrons. Electrons have almost no mass
  • Different for each isotope
  • E.G., a uranium atom has 92 protons and 143 neutrons for a mass number of 235


  • Same element, same number of protons, different number of neutrons

Isotopes of Oxygen

  • has three naturally occurring isotopes: 16O, 17O, and 18O
  • the most abundant is 16O
  • a small percentage of 18O and an even smaller percentage of 17O
  • Oxygen isotope analysis considers only the ration of 18O to 16O

Connection between temperature and climate

  • The 18O/16O ratio provides a record of ancient water temperature.
  • Water 10 to 15 C (18 to 27 F) cooler than present represents glaciation.
  • As colder temperatures spread toward the equator, water vapor rich in 18O preferentially rains out at lower latitudes.
  • The remaining water vapor that condenses over higher latitudes is subsequently rich in 16O.
  • Precipitation and therefore glacial ice contain water with a low 18O content.
  • Since large amounts of 16O water are being stored as glacial ice, the 18O content of oceanic water is high.
  • Water up to 5 C (9 F) warmer than today represents an interglacial, when the 18O content of oceanic water is lower.