Lecture #12 Global Change

Five major global change factors

• Elevated atmospheric CO2

• Elevated reactive nitrogen

• Climate change

  • Temperature (warming)

  • Precipitation patterns

  • Snow melt date

• Land-use change

• Invasive species

What are four largest active pools in descending order

• Ocean

• Soil

• Atmosphere

• Plant mass

What are three of the largest fluxes un the global carbon cycle

• Respiration

• Photosynthesis

• Evaporation (surface water exchange)

Describe the primary drivers of increased reactive N cycling globally

• Synthetic N fertilizer

• Fossil fuel combustion

• Legume crops and green manures

Potential positive effects of increasing N deposition

• N is normally limiting —> fertilizer

Potential negative effects of increasing N deposition

• N saturation —> negative impact on soil microbial and fungi community,

  leaching of nutrients (e.g., Ca), leaching N into groundwater

• N deposition —> reduce plant tolerance for other stress (frost, drought), alter herbivore interaction

• N deposition —> loss of rare species, decrease species diversity

Potential positive effects of a warming climate

• Increase growing season

• Certain species benefit from increased warmth

• Species range shifts (???)

Potential negative effects of a warming climate

• Plant-pollinator mismatch

• Decrease snowpack (snow acts as insulator, protective cover for many alpine plants)

• Plant physiological stress, increase heat and drought-stress

• Species range shifts (???)

  • Alpine species nowhere to go?

Greenhouse effect

• A natural process where certain gases in the Earth's atmosphere trap heat, preventing it from escaping into space and warming the planet

Identify major greenhouse gases

• Methane

• Water vapor

• Carbon dioxide

Identify two primary causes of increased atmospheric CO2

• Burning of fossil fuels

• Deforestation

Explain/identify effects of invasive species on plants and ecosystems

• Outcompete native species (or not)

• Alter biogeochemical cycles

• Impact economically valuable species

• Other global change factors may favor spread of invasive species