Plant Ecology in a Changing World
  • Topics
    • Topic Overview
    • Biomes and Climates in a Changing World >
      • Adaptation, biodiversity, and environment
      • Climate constrains plant distributions
      • Biome and climate relationships
      • Deserts
      • Grassland, savanna, and shrub biomes
      • Forest biomes
      • Alpine and tundra biomes
    • Plant adaptation >
      • Plant microclimate 1
      • Plant microclimate 2
      • Leaf energy budgets
      • Water movement through the soil-plant continuum
      • Principles of photosynthesis
      • Photosynthesis responses to light and temperature
      • Environmental stresses limit resource capture and use
      • Nutrients in the environment
      • Adaptation to environmental stress
    • Resource Allocation Changes with Environment >
      • Architecture and canopy processes
      • Plant phenology and resource allocation enhance performance
      • Leaf economic spectrum
      • Life history and reproduction
      • Defense against herbivory
      • Plant competition
    • Plant Responses to a Changing World >
      • Global changes occurring today
      • Invasive species
      • Atmospheric CO2 impacts plant
      • C3/C4 photosynthesis and climate
      • Climate change and the global carbon cycle
      • Climate warming and its impacts
    • Engineering Plant Communities >
      • Remember Utah's past and envision our future
      • Restoration ecology
      • Managed ecosystems
      • Utah urban ecology
      • Urban ecological futures
  • Assignments
    • Assignment Overview
    • Discussion
    • Problem sets
    • Ecology & Global Changes
    • Plant ecology policy
    • Defense of policy
    • Exam #1
    • Exam #2
  • Campus
    • Campus Overview
    • Grasses
    • Green infrastructure >
      • GI Overview
      • Stormwater >
        • GI 1
        • GI 2
        • GI 3
        • GI 4
        • GI 10
      • Green roof
      • Pollinator >
        • Pollinator species
    • Trees of the Wasatch
    • Shrubs of the Wasatch
    • Invasives
  • Biomes
    • Biome Overview
    • Climate diagrams
    • Vegetation sight-seeing trip
    • Biome images
  • Models
  • Lab
Topic 10 - Water movement through the soil-plant continuum
 
Essential elements from Topic 10:

Topic 10 provides an overview of the forces that move water through plants and the ways that plants influence water transport.
 
1.Plants lose water to the atmosphere when taking in CO2 for photosynthesis. This water must be replaced to prevent desiccation.
2.Water moves as a liquid from the soil, through a plant, to the site of evaporation by following gradients in water potential from high to low. Water in the xylem is held under tension in a metastable state.
3.The state of water is measured as water potential. The water potential is the potential energy of water on a volumetric basis relative to pure water.
4. Water potential has four components: gravitational, pressure, osmotic and matric. Water moves in different directions on the basis of total water potential, which is the sum of the four components.
5. Matric potential is due to capillary forces. In soil we find capillaries in the pores between soil particles. In plants the relevant capillaries are the pores between the cellulose microfibrils that make up cell walls.
6.Water in plants is often in a metastable state, meaning it is beyond its boiling point. Water can remain in this state, as long as it is not nucleated by an air bubble. Plants have pit membranes between xylem conduits that can prevent the entry and spread of air bubbles. However, plants differ in their abilities to exclude air bubbles, leading to different "vulnerability curves" and therefore different environments in which the plants can survive.
7.Stomata regulate water loss by opening and closing (an active process) in response to environmental stimuli such as CO2, light, and water status.




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Jim Ehleringer, University of Utah