BIOL 1307 UNIT 4 LECTURE 4 ECOSYSTEMS ECOLOGY ENERGY FLOW AND NUTRIENT CYCLING

Energy flow

Moves through the components of an ecosystem

Chemical cycling

The transfer of materials within the ecosystem

Trophic structure

A pattern of feeding relationships consisting of several different levels

Food chain

The sequence of food transfer up the trophic levels

Herbivores are…

primary consumers

Secondary consumers…

Typically eat herbivores or zooplankton in aquatic ecosystems

Detritivores

Derive their energy from deam material produced at all the trophic levels

Decomposers

A subtype of detritivores; mainly prokaryotes and fungi; secrete enzymes that digest molecules in organic materals and convert them into inorganic forms

Biomass

The amount of living organic material in an ecosystem

Primary production

The amount of solar energy converted to chemical energy by an ecosystem’s producers for a given area and during a given period

Net primary production

Amount of chemical energy produced-amount used by producers to fuel their own cellular respiration/waste

Howis additional energy lost as it flows through an ecosystem?

Excretion, defecation, and organisms that die without being consumed

Only about ___ percent of the energy stored at each trophic level is available to the next level

10

The phosphorus cycle does ____ have an atmospheric component

NOT

What is the only source of phsophorus for terrestrial ecosystems?

Rocks

Describe the global phosphorus cycle

Plants abosrb phosphate ions in the soil to make organic compounds. Decomposers return phosphates to the soil.

What are the two abiotic reservoirs for nitrogen?

75% in the atmosphere (unusable N2) and 25% in the rocks and soil (nitrates)

Describe the global nitrogen cycle

Plants absorb nitrogen as ammonium or nitrate. Bacteria and archaea facilitate nitrogen fixation for plants.

What limits primary production in aquatic ecosystems?

Low nutrient levels of phosphorus and nitrogen

Eutrophication

Primary production increases dramatically, but as plant matter decays/dies, decomposers deplete oxygen levels

Eutrophication decreases species diversity because…

Sunlight cannot penetrate the slimy mat of cyanobacteria, killing other photosynthetic life. Depletion of oxygen kills both photosynthesizers and aquatic species.

Where can nitrogen and phosphate pollution leading to eutrophication come from?

Agricultural fertilizers, pesticides, sewage treatment facilities, and runoff of animal wastes from feedlots

What can degrade aquatic ecosystems?

A rapud inflow of nutrients

Describe the global water cycle

It begins with water ecaporating out of the ocean and precipitating back into it. The cycle is completed by water that moves from the land to the oceans via streams and groundwater

Describe the carbon cycle

photosynthetic protists (plankton) take in CO2 from the atmosphere and reduce/fix it to form sugars

How does the destruction of large forests disrupt the carbon and water cycles?

By preventing the removal of CO2 from the atmosphere and reduces the amount of water released to the atmosphere, reducing overall precipitation

How are the carbon and water cycles disrupted?

Burning fossil fuels moves carbon from an inactive geological reservoir to an active reservoir. The burning of gasoline releases carbon atoms. Rising greenhouse gases change gobal climate change.

What causes the increase of greenhouse gases in the atmosphere?

Burning of fossil fuels

Global warming

The increase in the average temperatureof the planet

Global climate change

The sum of all the changes in local temperature and precipitation patterns that result from global warming

Although the world has been warmer in previous eras, climate change is concerning because…

Temperature is increasing rapidly, consistently with rising CO2 levels

As soil moisture changes, plant productivity will __________

change

What is the consequence of reduced primary productivity in drier areas?

Increased risk of fires

Excess carbon dioxide in the atmosphere ________ the oceans and _______ their temperatures

acidifies; raises