Trophic Dynamics & Decomposition (2)

What direction does energy flow in ecosystems?

Energy flows up through trophic levels.

Does matter flow or cycle in ecosystems?

Matter cycles; it is recycled, not lost.

What forms the basis of a trophic pyramid?

The summed biomass of each trophic level in a community.

Do terrestrial and aquatic trophic pyramids differ?

Yes, terrestrial pyramids are usually upright while aquatic systems may be inverted.

What is an inverted trophic pyramid?

A pyramid where higher trophic levels have more biomass than lower ones.

Where are inverted trophic pyramids most common?

Marine and aquatic systems.

Why do marine systems show inverted pyramids?

Primary producers have rapid turnover and are consumed quickly.

What mechanism contributes to inverted pyramids?

External foraging by mobile consumers.

What mechanism contributes to inverted pyramids?

Higher transfer efficiency between trophic levels.

What mechanism contributes to inverted pyramids?

Rapid turnover at lower trophic levels.

What mechanism contributes to inverted pyramids?

Larger body size at higher trophic levels.

What is trophic efficiency?

The proportion of total energy at one trophic level that is transferred to the next.

What is consumption efficiency?

The proportion of available biomass at one trophic level that is ingested by the next level.

What is assimilation efficiency?

The proportion of ingested food that is assimilated by the organism.

What is production efficiency?

The proportion of assimilated energy used to produce new consumer biomass.

What is the general rule for energy transfer between trophic levels?

Approximately 10% of energy is transferred to the next trophic level.

What is detritus?

Dead organic material including dead organisms and shed tissues.

What is litter?

Dead plant material such as leaves, stems, and wood.

What are examples of organic compounds in detritus?

Cellulose and lignin.

What are examples of inorganic compounds in detritus?

Nitrate, ammonium, phosphate, carbon dioxide.

What is fragmentation in decomposition?

Physical breaking of detritus into smaller pieces.

What is mineralization?

Conversion of organic molecules into inorganic molecules.

What is reuptake in decomposition?

Absorption of soluble nutrients released during decomposition.

What are the three decomposition processes?

Leaching, physical fragmentation, chemical alteration.

What is leaching?

The dissolution and removal of nutrients by water, sun, or physical forces.

What causes physical fragmentation?

Weather, water, sun, and the activity of organisms.

What is chemical alteration?

Biological breakdown and chemical transformation of organic material.

Who performs chemical decomposition?

Animals, microbes, fungi, and bacteria.

What percentage of soil respiration is due to microbes?

Most soil respiration (majority) is due to microbial activity.

What factors influence decomposition rates?

Temperature, moisture, substrate quality, and decomposer community.

What does a high lignin content do to decomposition rate?

Slows decomposition because lignin is difficult to break down.

What does a high cellulose content do to decomposition rate?

Makes decomposition easier compared to lignin-rich material.

Why does marine primary production support inverted pyramids?

Phytoplankton reproduce rapidly and are consumed quickly, so standing biomass remains low even when productivity is high.

Why are body sizes larger at higher trophic levels in marine systems?

Larger predators can forage across large spatial areas, allowing external energy inputs.

How does transfer efficiency affect trophic structure?

Higher transfer efficiency allows more biomass to accumulate at higher trophic levels.

How does turnover rate affect trophic structure?

Faster turnover at lower levels reduces standing biomass while maintaining high productivity.

What is the relationship between energy and biomass in a trophic pyramid?

Energy dictates how much biomass can be supported at each trophic level.

What limits the number of trophic levels in an ecosystem?

Loss of energy at each transfer limits how many levels can be supported.

Why does energy decrease as it moves up trophic levels?

Energy is lost as heat during metabolic processes.

What happens to matter during trophic transfers?

Matter is recycled through decomposition and nutrient cycling.

What is the role of decomposers in ecosystems?

They return inorganic nutrients to the environment for reuse by primary producers.

What are the main decomposer groups?

Fungi, bacteria, and detritivorous animals.

What is the importance of microbes in decomposition?

They conduct the majority of chemical breakdown and nutrient release.

Why is decomposition essential for nutrient cycling?

It converts complex organic matter back into forms usable by plants.

Why does leaching occur early in decomposition?

Water quickly removes soluble compounds before physical or chemical breakdown proceeds.

What happens during chemical alteration?

Organic molecules are enzymatically transformed or oxidized by decomposers.

What is the main distinction between fragmentation and chemical decomposition?

Fragmentation is physical; chemical decomposition is biological.

Why do fungi play a major role in decomposition?

They produce enzymes that break down lignin and cellulose.

What is soil respiration?

The release of CO2 from soil due to microbial and root metabolism.

How do decomposers influence ecosystem productivity?

They regulate nutrient availability, influencing primary production rates.

What happens to nutrients released during mineralization?

They are taken up by plants, microbes, or leached into soil and water.

How does climate influence decomposition?

Warmer, wetter environments generally increase decomposition rates.

What is the connection between decomposition and energy flow?

Decomposition recycles matter while energy continues to flow upward through trophic levels.