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Biology LibreTexts

1: Global Processes

  • Page ID
    17483
    • Nora.jpg
    • Contributed by Nora Bynum
    • Instructor and Vice Provost for Duke Kunshan University (Environmental Science & Policy Division) at Duke University

    • 1.1: Atmosphere and Climate Regulation
      About 3.5 billion years ago, early life forms (principally cyanobacteria) helped create an oxygenated atmosphere through photosynthesis, taking up carbon dioxide from the atmosphere and releasing oxygen. Over time, these organisms altered the composition of the atmosphere, increasing oxygen levels, and paved the way for organisms that use oxygen as an energy source (aerobic respiration), forming an atmosphere similar to that existing today.
    • 1.2: Land Use Change and Climate Regulation
      The energy source that ultimately drives the earth's climate is the sun. The amount of solar radiation absorbed by the earth depends primarily on the characteristics of the surface. Although the link between solar absorption, thermodynamics, and ultimately climate is very complex, newer studies indicate that vegetation cover and seasonal variation in vegetation cover affects climate on both global and local scales.
    • 1.3: Soil and Water Conservation
      Biodiversity is also important for global soil and water protection. Terrestrial vegetation in forests and other upland habitats maintain water quality and quantity, and controls soil erosion.
    • 1.4: Nutrient Cycling
      Nutrient cycling is yet another critical service provided by biodiversity -- particularly by microorganisms. Fungi and other microorganisms in soil help break down dead plants and animals, eventually converting this organic matter into nutrients that enrich the soil.
    • 1.5: Pollination and Seed Dispersal
      An estimated 90 percent of flowering plants depend on pollinators such as wasps, birds, bats, and bees, to reproduce. Plants and their pollinators are increasingly threatened around the world. Pollination is critical to most major crops and virtually impossible to replace. For instance, imagine how costly fruit would be (and how little would be available) if its natural pollinators no longer existed and each developing flower had to be fertilized by hand.