Conservation Biology

• 75-80% of Iowa used to be prairie

• What determines what plants are in an ecosystem? → temp/precipitation

• Temp

  • Intensity of sunlight: most intense at equator

  • Continental climate: center of continents; far from big bodies of water that slow down dramatic swings in temp

    • Center of continents has cold winters and hot summers, near ocean is more uniform

  • Proximity to warm oceans: creates warm and humid hair temps

  • More humidity = more uniform temps throughout the day

• Precipitation

  • Big causes: global air circulation; wet near equator dry near 30 degrees north and south (Hadley cells)

  • Smaller causes: proximity to warm oceans, rain shadow effect

• Rain shadow effect: areas downwind of mountain ranges are dry, precipitation levels increase away from mountains

  • In US, air moves from west to east

  • Air absorbs H2O over Pacific Ocean

  • As air hits mountains, it rises and cools

  • Cool air can’t hold water, so it rains on windward side of mountains

  • On downward side of mountains, air is dry and is warming, so it tightly holds water

Ecosystem of the Midwest in 1830

• Tallgrass prairie: extends north to Canada, south to Texas, east to Indiana

  • Shoulder height

  • Very little exposed soil

  • High species richness

  • Fire dependent ecosystem

• Shortgrass prairie: occupies much of western half of US in valleys between mountains and extends into the Midwest

  • Shoetop to shin high

  • Lots of exposed soil

  • Moderate to high species richness

  • Mixes with several species of sage in some places

• Mixed grass prairie: Canada to Texas

  • Shortgrass prairie growing in dry places tallgrass prairie growing in wet places

  • Fire dependent in places

  • High species richness

• Sandhills mixed grass prairie

  • Pure sand soils → doesn’t hold moisture/nutrients well

  • Mixed grass prairie plants that can survive on sand soils

  • Low to moderate species richness

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