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Ecological succession is the process of change in a population following a disturbance in an ecosystem, leading to the regeneration or creation of a new community. Learn about primary and secondary succession, population biology, population density, population dispersion, and survivorship curves.
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KEY CONCEPT Ecological succession is a process of change in the species that make up a population in the community.
Succession occurs following a disturbance in an ecosystem and can affect population size. • Succession regenerates or creates a community after a disturbance. • a sequence of biotic changes • damaged communities are regenerated • new communities arise in previously uninhabited areas
primary succession — started by pioneer species • There are two types of succession. Ex: Glacier, New Island Key here: soil needs to be created so the process is much longer
secondary succession — started by remaining species • There are two types of succession. Ex: Forest fire, flood, earthquake Key here: soil is already present; surviving species colonize and have to start over; process is not as long
POPULATION BIOLOGY • Individuals of one species simultaneously occupying the same general area, utilizing the same resources, and influenced by similar environmental factors • 2 factors concerning populations • -fluctuations in population size • -factors that regulate populations.
POPULATION DENSITY • the number of individuals per unit area or volume Measuring Density It is usually impractical or impossible to count all individuals in a population, so ecologists use a variety of sampling techniques to estimate densities and total population size. 1. You can count all individuals in a sample plot, or quadrant. These estimates become more accurate as sample plots increase in size or number. 2. You may also estimate by indirect indicators such as number of nests or burrows or by droppings or tracks. 3. Finally one may use the mark-recapturemethod. In the mark-recapture method, animals are trapped within boundaries, marked and after time retrapped.
POPULATION DISPERSON-how organisms are spread out in a population • CLUMPED • UNIFORM • RANDOM
SURVIVORSHIP CURVES=Survivorship curves plot the numbers in a cohort still alive at each age • SKETCH THE SURVIVORSHIP GRAPH ON THE BACK OF YOUR PRE-LAB SHEET