Succession/Population Dynamics By Diana Bivens

Why do organisms live where they do? Limiting factors: anything living or not that restricts the number of a particular organism in an area How might a cold climate be a limiting factor? Dry climate? Salt water?

Why do organisms live where they do? Tolerance range: the ability of an organism to adjust to environmental fluctuations -Catfish need little oxygen and can live in warmer water -Bass/Trout need more oxygen and need much colder water

Changes in an ecosystem Changes in the environment can affect organisms that live there Succession: orderly natural changes that take place over time and occur in stages

Primary Succession Primary succession: the colonization of new areas by organisms -pioneer species: the first organisms to colonize an area (usually mosses and lichens) The decay of pioneer species produces soil With soil comes the ability to sustain larger species

Primary Succession http://bcs.whfreeman.com/thelifewire/content/chp55/55020.html

FOREST FIRE PHOTOS USFS Controlled Burn Forest Fire, Flathead National Forest, Montana   Stock Photos of Flathead National Forest, Montana                                                                                                                         For Stock Photo Pricing Contact Us     Buy a Print  Return to Montana Stock Photos Collection      Return to Industry/Tourism Photos     Home For More Photos Succession Secondary succession: the community changes that occur after it has been destroyed by a natural disaster or human activity The land already contains soil The pioneer species will differ from that in primary succession

Primary vs. Secondary Succession http://www.geowords.org/ensci/imagesbook/04_03_succession.swf

Succession Climax community: a mature, stable community in which little or no succession occurs -will the climax community be the same in all areas? Why or why not?

Population Dynamics Population: a group of the same species that interbreed and live in the same area at the same time

Population Dynamics Density: the number of individuals per area Dispersion: arrangement of individuals within a given space Even Clumped Random

Calculating Growth Equation: (births- deaths ) + (immigration-emigration) = growth

r-strategists vs. K-strategists Population Dynamics r-strategists vs. K-strategists mosquito elephant short life span long life span many offspring few offspring little/ no parental care greater parental care

J curve Population Dynamics Populations grow exponentially when resources are unlimited J curve

S curve Population Dynamics A population will eventually reach its carrying capacity Carrying capacity: the number of one species an area can support S curve

What limits population size? Resource limits Carrying capacity is reached when the consumption of a resource matches the production of that resource Competition Members compete for limited resources Members compete for territories

Population Regulation Density dependent deaths: rapid deaths that occur within dense populations Disease, predation, limited resources Density independent deaths: deaths that occur regardless of a populations density Natural disasters, severe weather

Competition and Populations When populations are low, resources are plentiful When populations increase, resources become scarce-

Predation and Populations Predator-prey relationships help maintain population numbers As prey numbers fluctuate, predator numbers follow

Human Population Growth

Human Population Growth Demography: the study of human population growth Growth rate: the difference between births and deaths Which country would you expect to see the highest growth rate? United States or Zimbabwe?

Human Population Growth Developed countries are seeing a leveling off of population levels. Growth rates U.S. : 0.6% Germany: -1.5% Zimbabwe: 2.5%

Human Population Growth Other factors affecting growth Age structure of a population Immigration and emigration

Calculating growth rates Equation: (births- deaths )+(immigrants-emigrants)=growth