Biogeography

Evapotranspiration and MN environments

  • Why are there so many lakes in Minnesota?

    • Glaciers - left behind landscape to capture water easier

  • 2 opposing climate factors that allow water to retain

    • Precipitation - moves moisture from atmosphere to land surface

    • Evaporation + transpiration - process of water movement through plants, leads to evaporation 

    • ^ water is transpired through stomata, small pores in leaves that must be open to take up CO2

    • Evapotranspiration - transport of water into the atmosphere from all surfaces, including soil (evaporation) and from vegetation (transpiration)

  • Factors that affect evapotranspiration

    • Air temp - big factor

    • Atmospheric humidity 

    • Soil + plant water content 

    • Solar radiation 

    • Wind speed

  • (In MN) Precipitation is greater than ET - (In Arizona) its opposite

Grass vs Trees

  • Plants

    • Net carbon gain - the difference between carbon gain in photosynthesis and carbon loss due to respiration 

    • Nocturnal - active at night (stomata closed during day, open at night)

    • Located underground - reduce its exposure to stress and predators

  • How do plants allocate biomass?

    • Allocate carbon to grow plant’s root

  • Advantages 

    • Leaves tend to be relatively small

    • Few stomata

    • Less biomass above ground surface

    • Less at risk at what might be going on above ground

Leaves vs. needles

  • Four functions of leaves

    • Capture sunlight - helps generate sugars + build their bodies

    • Capture CO2 - for their stomata

    • Regulate water loss

    • Thermal regulation 

  • Physiognomy - physical appearance of ecological communities or species

    • Trees have branches + leaves

  • Needle like leaves advantages

    • Evergreen needle leaves

    • Not damaged by freezing temps

    • Transmit less water

    • Transmit less heat

    • Even in winter, leaves can begin process of photosynthesis

  • Disadvantage 

    • Individual leaves are quite small

    • Leaves cause trees to lose water

  • Broad leaves

    • Deciduous

    • Large surface area to capture more light 

    • More stomata

    • No leaves/water conservation and resilience to freezing 

  • Disadvantage 

    • Each tree must regrow its entire set of foliage every year (has to go through the whole process of losing its leaves)

    • Tree can only photosynthesize at a certain time

    • Found in areas that more moist

Biome Concept

  • Large terrestrial ecosystem characterized by specific plant communities and formations

  • Climatic space - mapping biomes out 

    • (graph) Wet in the east, dry in the west, warm in the south, cold in the north

    • Climate is the major factor that influences the distribution of terrestrial biomes

  • Ecological equivalents - vegetation formations that share physiognomy and structural characteristics but are widely separated in space and compromised by distinct species

    • Grasslands 

  • Graph tell - if there is a hump (Northern hemisphere)

  • (right graph) - relatively wet place, every month has a bar

  • (left graph) - closer to equator