Biotic and Abiotic Factors Page 90
Biotic factors • Biotic factors—living things with which an organism might interact. • The ecological community • Example—the frog
Abiotic Factors • Abiotic factor—physical, or nonliving, factors that shape ecosystems • Temperature, precipitation, wind • Example—the frog
Populations—Pages 119-132 • Factors affecting population size: • Birth rate • Emigration • Immigration
Populations • Birth rate—rate at which individuals are born into the environment • Population growth—when the birthrate is greater than its death rate • Population decline—when death rate exceeds birthrate
Populations • Immigration—the movement of individuals into an area. • Emigration—movement of individuals out of an area.
Populations • Carrying capacity—the largest number of individuals that a given environment can support.
Populations • Exponential growth—when individuals in a population reproduce at a constant rate • Under ideal conditions with unlimited resources, a population will grow exponentially. • Bacteria vs. Elephants
Populations • Logistic growth—when a population’s growth slows or stops following a period of exponential growth • Why may this occur?
Density-dependent factors • Density-dependent factors—limiting factor that depends on population size • Include: • Competition • Predation • Parasitism • Disease
Density-independent limiting factors • Density-independent limiting factor—affect all populations in similar ways, regardless of the population size. • Examples:
Human population • Human populations start with high birth and death rates. • As countries modernize medicine and sanitation improves and the death rate goes down. • Age-structure diagrams --graphs people by age and gender
Impact of people on Earth—pages 143-160 • Urban development—consumes farmland and natural habitats. • Can place additional stress on animal and plant populations • Industrial growth—certain kinds of industrial processes pollute air, water, and soil.
Impact • Pollution—harmful material that can enter the biosphere through land, air, or water • Biological magnification—concentrations of a harmful substance increase in organisms at higher trophic level: DDT
Impact • Ozone depletion—beginning in the 1970s the hole found in the ozone layer has grown larger and lasted longer • Causes: CFCs (chlorofluorocarbons) can linger for more than a century • Effects: Global warming • The increase in the average temperature of the biosphere
Impact • Renewable resources—can regenerate if they are alive or can be replenished by biochemical cycles if they are nonliving • Not unlimited • Nonrenewable resources—cannot be replenished by natural processes
Impact • Biodiversity—the sum total of the genetically based variety of all organisms in the biosphere • One of the earth’s greatest natural resources • Conservation—the wise management of natural resources
Picture credits • http://www.tarleton.edu/~range/Cook%20Pictures/Photo%20Slides_4/184%20coral%20bean.jpg • http://jrscience.wcp.muohio.edu/birds/ohio_birds/images/bull_frog_face_04_17.jpg • www.ipmthailand.org/images/Components/rain.gif • http://www.on.ec.gc.ca/wildlife/factsheets/images/glfs-osprey-chicks-f.gif • http://www.drhadwentrust.f2s.com/%5BFS-WA%5Dpopulatn250Hat42.JPEG • http://blogs.cocoondev.org/mpo/images/2003/02/24/jef.jpg • http://www.lkwdpl.org/schools/elempath/immigration/immig3.jpg • http://www.societehisto.com/Musee/Mission-Colon/Photos/emigration.jpg • http://www.virtuallaboratory.net/Biofundamentals/labs/EColi%20introduced/graphics/exponential%20growth.jpg • http://astro.temple.edu/~sanders1/LogGrwthCrv.gif • http://curriculum.calstatela.edu/courses/builders/lessons/less/biomes/bgifs/drink.gif • http://www.nwf.org/nationalwildlife/images/122006/photocontest_owl.jpg • http://spin-doctor.us/img/clear-cut.jpg • http://www.foxnews.com/images/139437/1_21_092604_st_helens.jpg • http://www.algebralab.org/img/fba2228e-1ba1-47a7-b6a2-8e9399ad21c5.gif • http://www.ess.co.at/SUTRA/CITIES/visuale.jpg • http://www.power-technology.com/projects/beilungang/images/img2.jpg • http://www.swanuk.org.uk/nest%20built%20from%20pollution%20-%20regents%20canal,%20hackney.jpg • http://www.lbl.gov/Education/HGP-images/air-pollution.jpg • http://www.met.sjsu.edu/~cordero/education/ozone_hole_where.jpg • http://www.midamericanenergy.com/eew/learn/images/3b_wind.jpg • http://images.google.com/imgres?imgurl=http://orgs.unca.edu/tulula/images/biodiversity.jpg&imgrefurl=http://orgs.unca.edu/tulula/biodiversity.html&h=309&w=360&sz=43&hl=en&start=2&tbnid=DBG_OeVLJldzNM:&tbnh=104&tbnw=121&prev=/images%3Fq%3Dbiodiversity%26svnum%3D10%26hl%3Den%26lr%3D