Scientists conducted a study in a temperate grassland ecosystem in North America to measure how energy is transferred between trophic levels.
They collected data on the total energy available at each level of the food chain by sampling plants, herbivores, and predators over a five-year period.
The table below summarizes their findings.
Energy Transfer in a Grassland Ecosystem
Trophic Level | Energy Available (kJ/m²/year) |
|---|---|
Producers | 10,000 |
Primary Consumers | 1,000 |
Secondary Consumers | 100 |
Tertiary Consumers | 10 |
Identify the trend shown in the table for energy transfer between trophic levels.
Describe how energy is lost as it moves from one trophic level to another.
A team of researchers wants to investigate the effect of an invasive herbivore on energy transfer within this grassland ecosystem.
They hypothesize that introducing a new herbivore species that consumes a large proportion of primary producers will disrupt the food web.
Identify a possible dependent variable in this investigation.
Identify a testable hypothesis the researchers could use in their investigation.
The researchers expand their study by analyzing changes in predator populations after the invasive herbivore is introduced.
They find that predator numbers decline over time.
Explain why predator populations decreased following the introduction of the invasive herbivore.
The researchers decide to repeat the study during different seasons to determine if environmental conditions affect energy transfer.
Describe one reason why energy transfer might vary between summer and winter.
Identify one abiotic factor (other than temperature) that could affect energy transfer in this ecosystem.
Describe how the removal of the invasive species could help restore energy flow in the ecosystem.
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