 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

PRIMARYSECONDARY  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  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 individuals Population 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 individuals Population density = unit area 1500 bullfrogs Population 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, …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.