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
Still in preparation - check back soon
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Topic 25 - Atmosphere and climate impact photosynthetic pathway advantages
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Essential elements from Topic 25:
Here we will talk about the ecology of C3-C4-CAM photosynthesis plants. While C4 plants represent less than 3% of world's number of plant species, C4 photosynthesis accounts for nearly 25% of the total terrestrial productivity.  CAM species contribute a marginal amount to global primary productivity. We discuss CAM as an evolutionary response to limited water in arid climates, a climate type that has existed since plants invaded land some 400 Ma.

In this lecture, we discuss how a changing atmosphere can favor either C3 or C4 plants. We discuss six topics related to the ecophysiology and ecology of C4 plants and to the comparative advantages of C3 versus C4 photosynthesis in different environments. The topics include:
  1. C3 is the ancestral photosynthetic pathway and is still the most abundant photosynthetic pathway
  2. Photorespiration as a constraint on photosynthesis in a high O2 and low CO2 world
  3. Multiple and different lines for the evolution of C4 plant taxa
  4. Expansion of C4 ecosystems and the advantages of C4 photosynthesis under conditions of low CO2 and high temperature
  5. Impacts of expansion of C4 ecosystems and evolution of grazing mammals
  6. On connectivities between photosynthetic pathway and herbivory and the implications in a changing world


Click here to download PDF of slides associated with Topic 25
Click here to view YOUBE videos on Topic 25
Jim Ehleringer, University of Utah