AP Environmental Science Ecology, Ecosystems, & Food Webs © Brooks/Cole Publishing Company / ITP 1. Ecology & Life Ecology- study of relationships between organisms & their environment. Levels of organization of life: organism population community ecosystem biome biosphere increasing size Organisms Organism- 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. Populations 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. © Brooks/Cole Publishing Company / ITP Communities 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. © Brooks/Cole Publishing Company / ITP Ecosystems & 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. © Brooks/Cole Publishing Company / ITP Major Components of Ecosystems Abiotic- non–living components examples: water, air, nutrients, & solar energy Biotic- living components (=biota) examples: plants, animals, & microorganisms © Brooks/Cole Publishing Company / ITP 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. © Brooks/Cole Publishing Company / ITP 2. Earth's Life–Support Systems 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 The Earth contains several spherical layers CrustOutermost, thin silicate zone, eight elements make up 98.5% of the weight of the earth’s crust MantleLargest zone, rich with iron, silicon, oxygen, and magnesium, very hot Lithosphere Crust and upper mantle CoreInnermost zone, mostly iron, solid inner part, surrounded by a liquid core of molten material Inner Core is hotter than surface of the Sun Atmosphere 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 What Sustains 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 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? © Brooks/Cole Publishing Company / ITP Nutrient Cycles Nutrient- any atom, ion, or molecule an organism needs to live, grow, or reproduce. • Macronutrients needed in large amounts e.g., C, O, H, N, P, S, K, Ca, Mg, Fe • Micronutrients needed in small amounts e.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. © Brooks/Cole Publishing Company / ITP Major Components of Ecosystems Major components of aquatic ecosystems. © Brooks/Cole Publishing Company / ITP Limiting 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. © Brooks/Cole Publishing Company / ITP Range of Tolerance There is a range of tolerance for temperatures that fish can live in. © Brooks/Cole Publishing Company / ITP Major 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. © Brooks/Cole Publishing Company / ITP Includes herbivores, carnivores, decomposers, etc. Photosynthesis & 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 C6H12O6 + O2 carbon dioxide + water + energy 6 CO2 + 6 H2O + energy **TRANSFER OF CARBON BETWEEN ORGANISMS WITH THESE TWO PROCESSES!! © Brooks/Cole Publishing Company / ITP Consumers Consumers (= heterotrophs) • Primary consumers- (herbivores) feed directly on producers • Secondary consumers- (carnivores) feed on primary consumers • Tertiary consumers- feed only on carnivores © Brooks/Cole Publishing Company / ITP Other 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 © Brooks/Cole Publishing Company / ITP 4. 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!!! © Brooks/Cole Publishing Company / ITP Food Webs & Energy Flow Example of some of the complexity of a food web in Antarctica. © Brooks/Cole Publishing Company / ITP Energy Pyramids As energy flows through trophic levels there is a conversion of usable energy to heat—2nd law of thermodynamics Rarely 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 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. © Brooks/Cole Publishing Company / ITP Pyramids of Numbers Pyramids of numbers- show the number of organisms at each trophic level. © Brooks/Cole Publishing Company / ITP Primary 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] OR Biomass 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. © Brooks/Cole Publishing Company / ITP Sun Respiration Gross primary production Energy lost & unavailable to consumers Net primary production Growth and reproduction (energy available to consumers) Primary 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!! © Brooks/Cole Publishing Company / ITP 5. 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 Cycle CO2 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 rocks 2. oceans Carbon Cycle Animation Carbon Cycle Ways 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 Cycle Ways 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 Cycle Much 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 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 Cycle Ways 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 © Brooks/Cole Publishing Company / ITP 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 Troposphere 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.