name: inverse layout: true class: center, middle, inverse --- # Transport I: water --- # How does water get to the top of trees? ---
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# "Hyperion" - 115.61 metres # Sequoia sepervirens ---
-- ##99.6 m ##Eucalyptus regens ---
--- # Trees are amazing but every biological system has limits
## What happens during droughts? --- layout: false .left-column[ ## C3 plants transpire a lot ] .right-column[ A tree might transpire >400 liters in a day ] ---
--- #Getting CO2 into the leaf means losing water
--- #Plants compete for sunlight by growing tall, and water is needed at the site of photosynthesis, so water transport is a competitive problem. --- # Root pressure was the obvious hypothesis, like a pump --- # Cutting down a tree doesn't make a fountain
--- # Cohesion-tension theory ## (1894 by John Joly and Henry Horatio Dixon)
--- # A bit of anatomy: stems
--- class: center, middle #A closer look
At maturity the protoplast--the living material of the cell--dies and disappears, but the lignified cell walls persist. --- #Features of the pipes: vessels versus tracheids ### Differences between trachedis (all vascular plants) and vessels (special cell only in 99% angiosperms) ### Max diameter of the vessel is bigger. This matters a lot! See Hagen-Poiseuille equation (Resistance ~ diameter
4
) ### Stackable: vessel elements can stack without the water going through pits ### Bigger elements, in general, are more susceptible to *embolism* --- ### evolution of water transport
Moving from the water onto land and then onto the driest land --- class: center, middle ##A bit closer still: the complex trade-off of connectedness
--- # 4 things that effect the potential energy of water (ie. can drive water flow) 1. Gravity 2. Pressure 3. Solute Potential 4. Matrix Potential ---
--- # Water potential is additive
--- class: center, middle, inverse #Everything in one picture, will come back to this
--- # First "artificial tree" in 2008 at Cornell
--- # First "artificial tree" in 2008 at Cornell
--- # First "artificial tree" in 2008 at Cornell
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### Notice that the salty water has a negative water potential --- # Measuring water potential
--- # Trees are amazing but every biological system has limits
## What happens during droughts? --- # Bubbles = embolism! (like a stroke but for a tree)
--- #Key structures: - Vessel elements (like big tracheids with special connectors, only angiosperms) - Tracheids (all vascular plants, everything after mosses) - Pits - Phloem - Stomata - Cambium --- #Key concepts: -Transpiration-photosynthesis compromise -Water potential -Cohesion-tension theory -Embolism