Ch 55 - Ecosystems & Restoration Ecology

Question 1

Describe the laws of thermodynamics & conservation of mass.

Answer 1

• Laws of thermodynamics:

1. Energy cannot be created or destroyed; only converted
2. Conversions are very inefficient; some energy lost as heat

• Law of conservation of mass:
  
  • ​Matter cannot be created or destoryed

Question 2

Describe ecosystem energy budgets: GPP vs. NPP vs. NEP.

Answer 2

• GPP: gross primary production; the total amount of energy from light converted to the chemical energy of organic molecules per unit time.
• NPP: net primary production; the GPP of an ecosystem minus the energy used by the producers for respiration
• NEP: net ecoystem production; the GPP of an ecosystem minus the energy used by all heterotrophs & autotrophs for repsiration (so, not just primary producers)

Question 3

Describe primary production and limiting factors of aquatic and terrestrial systems.

Answer 3

• The amount of light energy converted to chemical energy (organic compounds) by autotrophs in an ecosystem during a given time period
• Aquatic systems are limited by nutrients & light
• Terrestrial systems limited by temperature & moisutre (evapotranspiration)

Question 4

Describe secondary production and production efficiency. Describe efficiency rates of different organisms.

Answer 4

• Secondary production: the amount of chemical energy in consumers’ food that is converted to their own new biomass
• Production efficency: energy that is not lost via respiration or feces.
• Only the energy stored as biomass is what’s available to higher consumers
• Birds & mammals: 1-3% efficiency, fish: ~10%, insects: up to 40%.

Question 5

Describe trophic efficiency in terms of energy transfer between levels.

Answer 5

**Trophic efficiency **is described as the percent of energy transferred up to the next trophic level:

5-20% depending on ecoystem, average: 10%

Question 6

Describe the carbon nutrient cycle.

Answer 6

• Many reservoirs of carbon: fossil fuels, soils & sediments, oceans, organisms & in atmosphere
• CO₂ cycled via respiration and photosynthesis
  
  • Also released via volcanoes, deforestation, and burning of fossil fuels.

Question 7

Describe the water nutrient cycle.

Answer 7

• Reservoirs in ocean, 2% glaciers & polar ice caps, 1% in lakes, rivers & groundwater
• Moves via evaporation, transpiration, condensation, precipitation, and through surface & groundwater

Question 8

Describe the nitrogen nutrient cycle.

Answer 8

• Nitrogens present as amino acids, proteins, and mucleic acids
• Main reservoir: atmospheric nitrogen gas:
  
  • Must be fixed by plants into ammonium or nitrate for use
• Process reverses as organic nitrogen decomposes:
  
  • ammonification, nitrification, then denitrification

Question 9

Describe the phosphorous nutrient cycle.

Answer 9

• Required as nucleic acids, phospholipids, ATP, and some proteins
• Major reservoirs include: marine sedimentary rocks, oceans, and organisms as inorganic phosphate.
• Weathering of rocks adds phosphate to soil, binds with soil particles becoming less mobile, so are localized (not global). Some leached into sea. Then taken up by producers, eaten by consumers, then returned to soil via decomposition/excretion.

Question 10

Describe biomediation vs. biological augmentation in terms of restoration ecology.

Answer 10

• Biomediation: organisms detoxifying polluted systems, e.g. plants, bacteria, fungi
• Biological augmentation: organisms which add essential materials back to degraded systems, e.g. nitrogen fixters (facilitators)