BIOL-208 Lecture Notes - Lecture 19: Algal Bloom, Terrestrial Ecosystem, Evapotranspiration
17 Dec 2016
School
Department
Course
Professor
Production and Energy Flow
- Introduction
- Primary production: fixation of energy by autotrophs in an ecosystem
- Photosynthesis by plants and phytoplankton
- Rate of primary production: energy fixed over a given period of time
- Gross primary production: total amount of energy fixed by autotrophs
- Net primary production: energy left after autotrophs have met metabolic needs
- Trophic level: positions in food web
- First: primary producers
- Second: primary consumers
- Third: secondary consumers; carnivores
- Fourth: carnivores that feed on carnivores
- All levels: Parasites and detritivores and prey
- Terrestrial Primary Production
- Patterns
- Variables highly correlated with terrestrial primary production
- Temperature
- Moisture
- Highest rates in warm and moist conditions
- Canada
- 78% of net primary production occurs in the boreal forest
- Even though forests occupy about 40% of land
- Actual evapotranspiration and terrestrial primary production
- Actual evapotranspiration (AET): total amount of water that evaporates
and transpires during given time period
- Measured in mm
- Affected by temperature and moisture
- Highest values in warm and moist places
- Terrestrial net primary production increases with actual
evapotranspiration
- Same ecosystem type but precipitation controls net primary production
because of warm temperatures
- Back to plots with greatest variability: primary production increases with
more precipitation because of soil fertility
- Soil fertility
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- Add nitrogen, phosphorous, and potassium
- Increases net primary production by 23 to 300%
- Individual plant groups
- cryptogams/dwarf shrubs decreased
- Larger shrubs/trees: increased
- Herbs: increase or decrease, depending on type
- Aquatic Primary Production
- Patterns
- Generally nutrient limited
- Primary production and nutrient concentration
- In lakes and ocean is well studied
- Strong positive correlation
- Nutrients by primary production is strong
- Higher phosphorus concentrations are associated with greater algal
biomass
- As algal biomass increases so does the rate of primary production
- Higher rates of marine primary production take place along continental
margins and in shallow seas
- Too much primary production
- Satellite image of surface algal bloom in North Basin Lake in
Winnipeg of August 29, 2005
- Largest ever observed on the lake
- Most chlorophyll polluted lake in the world
- Blue green algae is very toxic
- Dead zones in oceans from agriculture, etc
- Trophic Levels
- Pyramid represents amount of energy in different trophic levels
- Trophic level shows the trophic position in an ecosystem
- 4. Tertiary consumers
- 3. Secondary consumer
- 2. Primary consumer
- 1. Primary producer
- The higher on the pyramid, the less the energy
- The number of levels is limited
- Trophic levels and energy losses
- “Energy losses limit the number of trophic levels in ecosystems”
- Trophic dynamic view of ecosystems
- Trophic dynamics: energy transfer from one part of ecosystem to another
- Ecosystem concept: fundamental to the study of trophic dynamics
- Loss of energy is unavoidable: law of thermodynamics
- The total amount of energy in the universe is constant. Thus,
energy can only be transformed, and not created
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Primary production: fixation of energy by autotrophs in an ecosystem. Rate of primary production: energy fixed over a given period of time. Gross primary production: total amount of energy fixed by autotrophs. Net primary production: energy left after autotrophs have met metabolic needs. All levels: parasites and detritivores and prey. Variables highly correlated with terrestrial primary production. Highest rates in warm and moist conditions. 78% of net primary production occurs in the boreal forest. Even though forests occupy about 40% of land. Actual evapotranspiration (aet): total amount of water that evaporates and transpires during given time period. Highest values in warm and moist places. Terrestrial net primary production increases with actual evapotranspiration. Same ecosystem type but precipitation controls net primary production because of warm temperatures. Back to plots with greatest variability: primary production increases with more precipitation because of soil fertility. Increases net primary production by 23 to 300% Herbs: increase or decrease, depending on type.
