3.2 Interactions and Changes Occur in Ecosystems

An imbalance within an ecosystem of either biotic or abiotic factors or both can cause problems. Example: Drained wetlands used as farmland destroyed many organisms in the ecosystem).

All Things Change Factors that can cause ecosystems to change:

Bioinvasion – is when a non-native species is introduced, either intentionally or accidentally, into an ecosystem. A lack of predators, or a naturally stronger species, can result in the successful introduction of that species. Example: 100 starlings intentionally introduced to Central Park in New York in 1890 now number more than 200 million species. 25% of all plant species in Canada are NOT native (eg. Zebra mussels).

Poster Map of Invasion

Competition – involves living things competing with other living things in their community for limited resources such as food, water, and space to live.

Predation – occurs when an animal hunts other animals for food. Large numbers of predators will mean a decrease in the population of prey. A decrease in the population of prey will then mean a decrease in the population in predators. Finally, a decrease in the population of predators means an increase in the population of prey.

This relationship is cyclical and is typically sustained indefinitely unless human represent the predators, the result could lead to the extinction of the prey. (Fig. 3.6, pg 60)

Weather conditions can also affect the ecosystem. Poor conditions (eg Weather conditions can also affect the ecosystem. Poor conditions (eg. Drought) can slow or stop plant growth. Natural disasters such as floods or fires caused by lightning can also kill plants and animals.