Ecosystems are always changing.

Chapter 2

Section 3

Populations change over time.

Limiting factors: any factor or condition that limits the growth of a population in an ecosystem– Examples: a large population of predators will

limit the population of prey, a large population of prey will limit the population of predators, too much or too little of any biotic or abiotic factor makes an ecosystem unstable

Maintaining a balance

Carrying capacity: when a population has reached a state where it can no longer grow it has reached its carrying capacity– Living things have certain minimum requirements

for food, water, and living space– Different for each population

Ecosystems change over time.

Succession: the gradual change in an ecosystem in which one biological community is replaced by another

Primary Succession

After something like a lava flow destroys the ecosystem Primary succession occurs which is the establishment of a new biological community– Pioneer species: first living things to move into a

barren environment– As the pioneers grow, they weaken the rock

surface and break the rock down, decaying plant matter adds nutrients and forms soil allowing more plants and shrubs to take root and support insects, birds, and small rodents

Primary Succession

Secondary Succession

Takes place after a major disturbance to the biological community in a stable ecosystem, occurs after a forest fire or other natural event

Below the surface seeds and plants survive, after time grasses and small shrubs grow up and small animals return, eventually large trees return providing food for more types of animals

Secondary Succession