AP Environmental Science Ecology, Ecosystems, & Food Webs © Brooks/Cole Publishing Company / ITP.

AP Environmental ScienceAP Environmental Science

Ecology, Ecosystems,Ecology, Ecosystems,& Food Webs& Food Webs

© Brooks/Cole Publishing Company / ITP

1. Ecology & Life1. Ecology & Life

Ecology- study of relationships between organisms & their environment.

Levels of organization of life:

organism

population increasing size

community

ecosystem

biome

biosphere

OrganismsOrganismsOrganism- any form of life.

Species- organisms that resemble each other and can potentially interbreed.

•Estimated 5 to 100 million species, most are insects & microorganisms

•1.8 million named

• Each species is the result of long evolutionary history.

•Native species- population that exists in its natural habitat

•Non-native or introduced species- population introduced by humans.

PopulationsPopulations


Population- individuals of the same species in a given area

-Examples: sunfish in a pond, white oak trees in a forest, people in a city

• Habitat- the place where a population usually lives.

• Genetic diversity- in natural populations individuals vary in their genetic makeup.

CommunitiesCommunities


Community- populations of all species living together in a given area.

• It is a complex interacting network of plants, animals and microorganisms.

• Example: redwood forest community, consisting of populations of redwoods & other trees, shrubs and herbaceous species, animals and microorganisms.

Ecosystems & EcosphereEcosystems & Ecosphere


Ecosystem- a community of different species interacting with one another & with their non–living environment of matter & energy.

-Examples:Patch of woods, a lake or pond, a farm field, an entire watershed in a tropical rain forest.

Major Components of EcosystemsMajor Components of Ecosystems


Abiotic- non–living components

examples: water, air, nutrients, & solar energy

Biotic- living components (=biota)

examples: plants, animals, & microorganisms

What is Life?What is Life?


Characteristics of Life:

Organisms composed of cells that contain genetic material

Organisms capture & transform matter & energy from their environment to supply needs for growth, survival, & reproduction

Organisms maintain stable internal conditions through homeostasis

Organisms capable of reproduction

Organisms adapt to changes in environmental conditions through evolution.

Earth's major components:

Atmosphere- troposphere + stratosphere

Hydrosphere- all Earth’s water

Lithosphere- crust and upper mantle; contains fossil fuels and renewable soil chemicals

Biosphere- where living things reside; consists of most of hydrosphere, parts of lower atmosphere and upper lithosphere

2. Earth's Life–Support Systems2. Earth's Life–Support Systems

The Earth contains several

spherical layers Crust-

Outermost, thin silicate zone, eight elements make up 98.5% of the weight of the earth’s crust

Mantle-Largest zone, rich with iron, silicon, oxygen, and magnesium, very hot

Lithosphere- Crust and upper mantle

Core-Innermost zone, mostly iron, solid inner part, surrounded by a liquid core of molten materialInner Core is hotter than surface of the Sun

Atmosphere- thin envelope of air around the planet Troposphere

Up to 17 km above sea level, contains N (78%), O (21%), and is where weather occurs

Stratosphere

17-48 km above sea level and contains ozone (O3) to filter out most of the sun’s UV radiation

AtmosphereAtmosphere

What Sustains What Sustains Life on Earth?Life on Earth?Life on the earth depends on three interconnected factors

One-way flow of high-quality energy from the sun (**only 0.1% used for photosynthesis!)

Cycling of matter or nutrients through all parts of the ecosphere

Gravity-allows the planet to hold onto its atmosphere and causes the downward movement of chemicals in the matter cycles

Energy Flow & Nutrient CyclingEnergy Flow & Nutrient Cycling


Life on Earth depends upon one–way flow of high–quality energy from sun & cycling of crucial elements.

**Earth is an open system in regards to energy, and a closed system in regards to matter

What about living things?

Nutrient CyclesNutrient Cycles


Nutrient- any atom, ion, or molecule an organism needs to live, grow, or reproduce.

• Macronutrients needed in large amountse.g., C, O, H, N, P, S, K, Ca, Mg, Fe

• Micronutrients needed in small amountse.g., Na, Zn, Cu, Cl, I

• Nutrient cycles (biogeochemical cycles)- flow of nutrients from nonliving (air, water, soil, rock) to living organisms (biota) & back again.

•Driven directly or indirectly by solar radiation & gravity.

•Major cycles: hydrologic (water), carbon, oxygen, nitrogen, phosphorus and sulfur.

Major Components of EcosystemsMajor Components of Ecosystems


Major components of aquatic ecosystems.

Limiting FactorsLimiting Factors


Law of tolerance- a species’ livelihood in an ecosystem is determined by the levels of 1 or more physical or chemical factors falling w/in the range tolerated by that species.

•Limiting factor- regulates survival, growth, or reproduction.

•Limiting factor principle-too much or little of any abiotic factor can limit or prevent growth of a population, even if all other factors are at or near the optimum range of tolerance.

Range of ToleranceRange of Tolerance


There is a range of tolerance for temperatures that fish can live in.

Major Living ComponentsMajor Living Components


Two main categories:

1) Producers (autotrophs)-

• Photosynthetic: make their own energy source through photosynthesis ****Only 0.1% of sun’s energy gets used for this****

• Chemosynthetic: convert simple compounds into complex nutrients w/o sunlight, e.g., bacteria of thermal vents use H2S & CO2.

2) Consumers (heterotrophs)-

• Get energy & nutrients by feeding on other organisms or their remains.

• Includes herbivores, carnivores, decomposers, etc.

Photosynthesis & RespirationPhotosynthesis & Respiration


Photosynthesis- solar radiation is captured by chlorophyll (& other pigments)

carbon dioxide + water + solar energy glucose + oxygen

6 CO2 + 6 H2O + solar energy C6H12O6 + O2

Aerobic respiration- organic molecules (e.g., glucose) are used for an energy source

glucose + oxygen carbon dioxide + water + energy

C6H12O6 + O2 6 CO2 + 6 H2O + energy

**TRANSFER OF CARBON BETWEEN ORGANISMS WITH THESE TWO PROCESSES!!

ConsumersConsumers


Consumers (= heterotrophs)

• Primary consumers- (herbivores) feed directly on producers

• Secondary consumers- (carnivores) feed on primary consumers

• Tertiary consumers- feed only on carnivores

Other FeedersOther Feeders


•Omnivores- consumers that feed on both plants & animals

•Scavengers- feed on dead organisms

•Detritivores- feed on detritus (partially decomposed organic matter, such as leaf litter & animal dung)

•Decomposers- consumers that complete the breakdown & recycling of organic materials from the remains & wastes of other organisms

4. Food Webs & Energy Flow4. Food Webs & Energy Flow


Food chains involve a sequence of organisms, each of which is the food for the next.

**ARROW DIRECTION SHOWS FLOW OF ENERGY!!!

Food Webs Food Webs & Energy & Energy

FlowFlow


Example of some of the complexity of a food web in Antarctica.

Energy PyramidsEnergy PyramidsAs energy flows through trophic levels there is a conversion of usable energy to heat—2nd law of thermodynamicsRarely have more than 4 steps Ecological efficiency- percentage of USABLE energy transferred from one trophic level to anothertypically 10%Shown by pyramid of energy

10,000,000 units of energy from sun 10,000 units used by green plants (photosynthesis-0.1%) 1000 units for herbivores 100 units for primary carnivores 10 units for secondary carnivores

Biomass

Biomass- dry weight of all organic matter contained in organisms.

Water is not source of energy or nutrients

Biomass of first trophic levels is dry mass of all producers

Useable energy transferred as biomass (eaten)

Biomass PyramidsBiomass Pyramids


Biomass pyramids (dry mass)- show the biomass available at every level and can look like the energy pyramid (as for the abandoned field) or be inverted (as for the ocean).

Inverted biomass pyramids result because the majority of short-lived producers are eaten by larger, long-lived consumers.

Pyramids of NumbersPyramids of Numbers


Pyramids of numbers- show the number of organisms at each trophic level.

Primary ProductivityPrimary Productivity


•Gross primary productivity (GPP)- rate at which an ecosystem's producers convert solar energy into chemical energy as biomass.

•Net primary productivity (NPP)- rate at which energy for use by consumers is stored in new biomass (plant growth)

NPP = GPP – [rate at which producers use biomass]

ORBiomass growth available to consumers = GPP – plant aerobic respiration

***Planet’s NPP (energy output of producers) ultimately limits the number of consumers that can survive on earth.

Sun

Photosynthesis

Gross primaryproduction

RespirationEnergy lost &unavailable toconsumers

Growth and reproduction

Net primaryproduction(energyavailable toconsumers)

Primary ProductivityPrimary Productivity


Estimated annual net primary productivity of major biomes & aquatic life zones, expressed as kilocalories per square meter per year. **THIS FIGURE GIVE THE AVERAGE NPP PER UNIT AREA SO IT IS A MEASURE OF AN AREA’S NPP EFFICIENCY!!

5. Matter Cycling in Ecosystems5. Matter Cycling in Ecosystems

Nutrient (biogeochemical) cycles- Natural processes that recycle nutrients from the nonliving environment to living organisms and back again

Water, Carbon, Nitrogen, Sulfur, Phosphorus, etc.

Hydrologic Cycle

Carbon CycleCarbon CycleCO2 is an important temperature regulator on earth (greenhouse gas)

Combustion of fossil fuels release CO2

Carbon cycles through the ocean, which releases more carbon dioxide with warmer temps

CH4 (methane)-principle component of natural gas and gases released from bacterial decomposition of waste in landfills.

Largest reservoirs of carbon? 1. carbonate rocks2. oceans

Carbon Cycle Animation

Carbon CycleCarbon CycleWays in which we’re interfering:

Burning fossil fuels Destruction of

photosynthesizing vegetation has contributed to global warming

The natural greenhouse effect is strengthened by warmer temps (more CO2 released from warmer ocean)—positive feedback

Excessive waste in landfills and global warming releasing more methane clathrates.

Methane clathrate video

Nitrogen CycleNitrogen CycleWays in which we’re interfering:

Nitric oxide released from burning fuel which produces nitric acid.

NONO2 HNO3 (nitric acid rain)

Nitrous oxide (N2O) released by bacteria acting on livestock wastes and fertilizers which warms atmosphere and depletes ozone

Destruction of forests, grasslands, and wetlands releases N into air

Pollution of aquatic systems with agricultural runoff and human sewage

Harvesting crops removes N Increased N in air, soil, water affecting

biodiversity

Sulfur CycleSulfur CycleMuch is stored in rocks

Burning coal, refining oil and producing some metals from ores (smelting) all add sulfur to environment (SO2 gas)

These are converted to sulfuric acid H2SO4 (acid rain)

DMS (dimethyl sulfide) released by algae and diffuses from oceans and can form sulfate particles, which causes cloud formation and possible regulation of climate

Phosphorus CyclePhosphorus Cycle

Important element in DNA, RNA, ATP.

Very slow because no gaseous state!

Found in soil, organisms, marine sediment, rock, and guano (bird and bat poop.)

Limiting factor for plant growth so used in some fertilizers

Limits growth of producers in freshwater streams and lakes due to low solubility (ability to dissolve)

Phosphorus Cycle Animation

Phosphorus CyclePhosphorus CycleWays in which we interfere

Mine phosphate rock to make fertilizers and detergents

Cut down tropical forests and reduce the phosphorus in tropical soils

Compromise aquatic systems with animal waste runoff and human sewage.

Leads to overgrowth of algae, which when decomposed leads to lowering of DO for aquatic life.

Banned in soaps and detergents in some states, EU, Japan, and Canada

7. Ecosystem Services & Sustainability


Ecosystem services- natural benefits that support life on the earth & are essential to the quality of human life & the functioning of the world's economies.

Examples:• control & moderate climate• recycle vital nutrients• provide energy & mineral resources• furnish food, fiber, medicine, timber, & paper• pollinate crops & useful native plants• absorb, dilute, or detoxify pollutants• control populations of pests & disease organisms• slow soil erosion & prevent flooding• provide biodiversity of genes & species

Two Principles of Ecosystem Sustainability

Use renewable solar energy as energy source

Efficiently recycle nutrients organisms need for survival, growth, and reproduction

Greenhouse gases in Greenhouse gases in TroposphereTroposphere

Water vapor

Carbon dioxide

Methane (CH4)

Nitrous oxide (N2O)

Ozone (O3)—major layer in stratosphere, dangerous in troposphere

These warm atmosphere due to absorption of sun’s radiation and release of longer wavelength, infrared radiation.

AP Environmental Science Ecology, Ecosystems, & Food Webs © Brooks/Cole Publishing Company / ITP.

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Transcript of AP Environmental Science Ecology, Ecosystems, & Food Webs © Brooks/Cole Publishing Company / ITP.