AGENDA Take out notebooks and pick up handouts

AGENDA Take out notebooks and pick up handouts! Warm-up: Succession/Limiting Factors Notes Succession Worksheet

Warm-up Discuss with your group… What kind of animals do you think will be present at each level?

• If grass were no longer cut on a lawn, what would it look like in a year? • Five years? • In 90 years?

Succession: Changes over Time • Ecologists refer to the natural changes that take place in an ecosystem over time as succession. • Succession occurs in very predictable stages • At each stage, different species of plants and animals may be present.

Succession: Changes over Time • As succession progresses, new organisms move in. • Others may die out or move out. There are two types of succession— • primary • secondary.

• The colonization of organisms in a completely barren land is called primary succession. • Primary succession takes place on land where there are no living organisms. • ‘starting from scratch’

PRIMARY SUCCESSION • The first species to take hold in an area like this are called pioneer species.

PRIMARY SUCCESSION • As these first organisms die, more soil builds- and it has more and more nutrients in it. Exposed rock Primary succession • As soil builds, bigger plants will grow, bringing in herbivores and eventually carnivores

SECONDARY SUCCESSION • Secondary succession is the sequence of changes that takes place after an existing community is severely disrupted in some way. • Secondary succession, however, occurs in areas that still have land containing nutrients in the soil. - Not completely starting from scratch, like primary.

• Succession occurs until a stable, mature community develops that undergoes little or no change in species is a climax community.

• In an evolving ecosystem, populations will continue to grow until they reach their carrying capacity. • This is the maximum amount of organisms that can survive in an ecosystem – It is determined by the amount of resources available, such as: • Habitat (space) • Water • Food No population can live beyond the environment’s carrying capacity for very long.

Logistic Population Growth Curve (label your graph on your outline) ● The “J” shape shows growth at a constant rate (exponential growth). ● When the “J” becomes an “S” shape…it means the population has reached carrying capacity.

Life In an Ecosystem • Conditions in one part of the world are suitable for supporting certain forms of life, but not others.

Ranges in Tolerance • The ability of an organism to withstand fluctuations in biotic and abiotic environmental factors is known as tolerance. For example, some crops may survive a long drought period. They may not produce as well, but they’re able survive.

• A limiting factor is any biotic or abiotic factor that can affect the existence of an organism. Common Limiting Factors Sunlight Climate Atmospheric gases Temperature Nutrients/Food Fire Soil chemistry Amount of Space Other organisms Water

Limiting Factors • Factors that limit one population in a community may also have an indirect effect on another population. For instance, what if a drought caused grass to reduce the number of seeds it produces… What would happen to the mice that feed on those seeds? What would happen to the hawks that feed on those mice?

What are some limiting factors for this If it’s too dry, Mr. Frog little guy? And why? can’t breathe…and if no water around, can’t reproduce.