Ecosystem Balance

Ch. 6Ecosystem BalanceRelationship in EcosystemEnergy is cycled in ecosystems

Predator: hunts other organisms

Prey: the huntedPraying mantis

Increases in a prey generally lead to increase in predator populations

Population Changes

http://www.rpdp.net/sciencetips_v2/images/l12c2/lynx-hare_cycle.gif

ParasitismOne organism feeds on tissues/body fluids of another (the host)ParasiteHarmful to hosts, but usually dont killLive on the body of hostDensity dependentPopulation size of parasite depends on population of hostSymbiosisTwo species live closely togetherExamplesParasitism: one species benefits, other is harmedAphids and plantsCommensalism: benefits one species and doesnt really affect the otherBarnacles and whalesMutualism: both species benefitPlants and insects that pollinate themUse the information below to answer the following.Aphids are insects that feed on fluids from the stems of plants. After the aphids ingest the plant fluids, they excrete a liquid called honeydew.Ladybugs eat aphids, which are a source of protein for the ladybugs. Which of these terms best describes the relationship between the ladybugs and the aphids?A. mutualism b. parasitehost C. predatorprey D. commensalism

Praying mantisA few examples of parasites are tapeworms, fleas, and barnacles. Tapeworms are segmented flatworms that attach themselves to the insides of the intestines of animals such as cows, pigs, and humans. They get food by eating the host's partly digested food, depriving the host of nutrients. Fleas harm their hosts, such as dogs, by biting their skin, sucking their blood, and causing them to itch. The fleas, in turn, get food and a warm home. Barnacles, which live on the bodies of whales, do not seriously harm their hosts, but they do itch and are annoying. Some parasitic animals attack plants. Aphids are insects that eat the sap from the plants on which they live. Parasitic plants and fungi can attack animals. A fungus causes lumpy jaw, a disease that injures the jaws of cattle and hogs. There are also parasitic plants and fungi that attack other plants and fungi. A parasitic fungus causes wheat rust and the downy mildew fungus attacks fruit and vegetables. Some scientists say that one-celled bacteria and viruses that live in animals and harm them, such as those that cause the common cold, are parasites as well. However, they are still considered different from other parasites. Many types of parasites carry and transmit disease. Lyme disease is trasmitted by deer ticks. Ecological SuccessionWhat happens to a lawn or garden overtime if it is not cared for?Ecological SuccessionSuccession: changes overtime to a landscapeTypes:Primary

Secondary

Aquatic

IslandPrimary SuccessionSequence of organisms coming to a lifeless habitatFirst: colonization by new organismPioneer Community: 1st to colonizeOn Land: rocks are colonized by lichensLichens: fungus and an algaSecrete acids to break down rock form organic materialHelp to form soilSecond: formation of soilThird: grasses and small plants (block light so no more lichen)Fourth: shallow root treesFifth: deep root treesClimax Community: undergoes no more growth/change (stable)Secondary SuccessionOccurs in area after a disturbance eliminates most organisms, but doesnt destroy soilUsually after human disturbances (fires)

Resembles later stages of primary succession

Will also eventually result in climax community

Example:grasslands

Aquatic SuccessionStarts as a nutrient poor lakeSupports few organisms

Overtime water plants begin to grow near the shore

Becomes more nutrient-rich

lake fills with sediment and becomes a marsh

Land plants move in; ultimately turns into a forestIsland SuccessionNew islands can form after volcanoes erupt

New organisms ancestors came there by water, wind, or hitching a ride

Majority have large bird populations

Offspring evolves to fill several nichesUsually is little competition for food/resources because few organisms

New species tend to form because mates may be difficult to come by and available niches

Ecological successionStability in the EcosystemStability: measure of how easily an ecosystem is affected by a disturbance and how quickly it returns to it original condition after the disturbance.

Equilibrium: disrupted ecosystem returns to a state of balanceDisruptionsMajor disruptions can cause drastic changes-even complete destruction of the ecosystemA new ecosystem will eventually evolve

DinosaursWere believed to go extinct due to the impact of a large object from spaceAfter the dinos were gone, many different kinds of mammals evolvedChaos TheoryChaos Theory: ecosystems may be sensitive to very small changesNow: species are becoming extinct at faster ratesReasons:Human population growthHabitat destructionIntroduction of foreign speciesPollution of fresh waterBiomesBiome: a major type of ecosystem with distinctive temperature, rainfall, and organismsLand (terrestrial)amount of precipitation and temperature

Water (aquatic)Water depth, nutrients, nearness to land

Biomass: total mass of organic material

Figure 9k-1:

Figure 9k-1: Distribution of the Earth's eight major terrestrial biomes. Legend is below. (Adapted from: H.J. de Blij and P.O. Miller. 1996. Physical Geography of the Global Environment. John Wiley, New

Land BiomesDesertTundraConiferous forestDeciduous forestRain forestSavannaTemperate Woodland and ShrublandSteppe and PrairieVery little water; small amt biomassForests: contain 75% Earths biomassRain ForestsCover 6% surface, but contains 50% biomass

Most diverse

Tropical Dry Forest: rainy season followed by dry seasonTemperate Woodland and ShrublandPrecipitation varies

Located only 5 areas-all on shorelines

Contain chaparral: low plants that contain flammable oilsCatch fire easily some plants have seeds that can only germinate after being exposed to fire