An ecosystem supports a certain size of population (carrying capacity), which can vary due to: the effect of abiotic factors; interspecific and intraspecific competition; predation
Every ecosystem has a carrying capacity — a maximum population size it can sustainably support. Abiotic conditions, competition between species, and predation all cause this limit to vary.
Real World
The reintroduction of wolves to Yellowstone National Park in 1995 reduced the elk population through predation, which lowered it closer to the carrying capacity the vegetation could sustain.
Exam Focus
Sketch and label an S-shaped growth curve — mark the carrying capacity line and where each limiting factor acts.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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