Succession means… act or process of following in order, sequence

Ecological succession means… Predictable and orderly changes in the

structure of an ecological community over time

Ecosystems responding/changing due to natural and human disturbances

In ecosystems community dynamics change as older organisms die out and new ones move in

PRIMARY SECONDARY

Growth occurs on newly exposed surfaces where no soil exists

Ex. Surfaces of volcanic eruptions

Growth occurring after a disturbance changes a community without removing the soil

For example, new land created by a volcanic eruption is colonized by various living organisms

Disturbances responsible can include cleared and plowed land, burned woodlands

Pioneer species First species to populate an area

Climax community Mature stable community achieved over time

which does not undergo further succession

Activity: Work with others at your table to individually

create a flow chart summarizing the steps of ecological succession in this ecosystem use information from pgs 96-97

What are the major phases of succession?

What changes occur? What types of organisms are involved?

Due Tuesday Interview a family member or neighbor

about succession in your neighborhood Have grassy or overgrown areas been

developed? Have farms, parks or lots returned to

their previous wild state? Over what period of time did changes

occur?

How many people are in this room? What is the area of the room in square

meters? How many people are there per square

meter?

number of individualsPopulation density = unit area

There are 1500 bullfrogs living in a pond that covers an area of 3 square kilometers. What is the density of the bullfrog population?

number of individualsPopulation density = unit area

1500 bullfrogsPopulation density = 3 square km

Population density = 500 bullfrogs per square km

Density Geographic distribution Growth rate

Number of individuals per unit area i.e. plants,

animals, etc. May be a lot of

variation depending upon species and ecosystem

Factors affecting size: number of births, number of deaths, and number of individuals entering and leaving the population

Immigration vs. emigration Migration Im – like in E – like exit

Under ideal conditions with unlimited resources, a population will grow exponentially

Reproduce at a constant rate

Ex. Initial bacterial growth, 2-4-8-16-32-64…etc.

J shaped curve

Available resources decline, growth slows, stops following a period of exponential growth

S shaped curve Carrying capacity

Max number individuals of a population that an environment can support

Limiting factors = factors causing population growth to decrease Ex. Competition, predation, parasitism,

disease, climate extremes, human disturbances

Density- Dependent Density - Independent

Limiting factor depending on population size

Population density reaches certain level Ex. factors include: competition,

predation, parasitism and disease

regulate populations according to the population density.

Specific example: a boom in the wolf population makes wolves start eating squirrels in addition to rabbits. This causes a more dramatic decrease in the squirrel population than previous records indicate.

Affect populations regardless of size Ex. factors include weather, natural

disasters, seasonal cycles and human activities

factors acting randomly, with reference to the population density, to regulate population size.

Specific example = freezing weather and heavy snow. During winter, either or both of these abiotic factors can

cause the population of moose to drop. With fewer moose on the island, the population of wolves also may decrease, because the wolves' primary food source becomes harder to find.