Tipping points, Ecosystem stability models, and Keystone Species

What is an ecosystem tipping point?

A critical threshold where change becomes difficult or impossible to reverse

What causes an ecosystem to reach a tipping point?

Excessive disturbance combined with positive feedback loops

What are positive feedback loops?

Processes that amplify changes and push systems toward a new equilibrium

Why is the Amazon rainforest an example of a tipping point?

Deforestation disrupts the water cycle and increases drought

What human activities contribute to Amazon deforestation?

Burning, grazing, housing development, timber extraction, and mining

Why is the Amazon rainforest important globally?

It contains half of Earth’s remaining tropical rainforests

What role does the Amazon play in the water cycle?

It generates atmospheric water vapour through transpiration and evaporation

How does deforestation disrupt the Amazon water cycle?

It reduces rainfall and increases drought frequency

What is a mesocosm?

A small experimental ecosystem used to study stability and sustainability

Why are mesocosms useful?

They allow controlled investigation of ecosystem variables

How can mesocosms be designed?

They can be sealed or open but controlled, with light as the energy source

What factors must be considered when designing a mesocosm?

Container type, transparency, organisms included, and oxygen supply

What is a keystone species?

A species critical to the survival of an ecosystem

Why are keystone species important?

Their removal can cause ecosystem collapse

What is an example of a keystone species?

The American beaver

How do beavers contribute to ecosystem stability?

They perform unique roles that shape habitats

What keystone species exist in Switzerland’s aquatic ecosystems?

Amphipods

Why are amphipods important?

They contribute to nutrient cycling, biodiversity, and serve as fish food