Ecosystem Structure and Function

 Ecology—study of the house  Scientific study of organisms and the environment  Intimate relationship between energy and matter  Energy?  Matter? Ecology  Studied at several levels  Smallest--Physiology of organisms, role of the environment in determining sex  Largest—biospheres

Ecosystem  Ecosystem –self-sustaining community of organisms and the physical environment in which they exist  Energy  Matter  Biotic factors--living  Abiotic factors—nonliving, all inclusive—weather, climate, soils, etc

2 Big Ideas  Energy Flows

 Matter Cycles

 Fixed amount of energy and matter Matter  Stuff  Elements—stuff that can’’t be broken down into simpler forms by ordinary means  Made up of small structures: atoms—smallest particles that maintain properties of element  Atoms—protons and electrons

Atoms  Protons—positive, mass  Neutrons—neutral, mass  Nucleus—center of mass, protons + neutrons  Electrons—negative, little mass, rotate around nucleus at speed of light

Terms  Atomic number—number of protons  Atomic mass—protons and neutrons  Isotopes—forms of an element with different atomic mass—hydrogen has 3 forms, may be unstable Molecules and Compounds  Molecules—groups of atoms  Compounds—molecules with different atoms  Held together with electrons—donate, shared  Bond formation—requires energy  Bond breakage—releases energy Molecules

 Carbohydrates  Lipids  Proteins  Nucleic acids  Water Cells  Basic units of life  Boxes of chemicals: carry out life processes  Location where matter and energy collide  Two basic energy processes: energy capture and release  Basis of ecology

Energy  Ability to do work  Exists in many forms: kinetic, potential, chemical, light, heat, etc.  High quality—intense,intense, concentratedconcentrated  Low quality—diffuse, dispersed Laws of Thermodynamics  Describe energy conversion in universe  First Law—energy neither created or destroyed  Second Law—energy flows in one direction, not 100% efficient  Increase in disorder (entropy)

Energy Flow  Biotic components collect, store and release energy

 Light energy -> chemical energy -> heat

Sun  Energy source for biotic components  Photosynthesis—traps light energy  Forms chemical energy  Used by all other organisms  Exception--chemosynthesis Photosynthesis  In the presence of chlorophyll and sunlight,

Water and carbon dioxide

 are converted to

 sugars and oxygen. Photosynthesis Streamlined Chemosynthesis • Some organisms and communities live without sunlight and are powered by chemosynthesis.

Energy Flow  Trophic level: feeding level

 Producers

 Consumers

 10% of energy in one level available for next higher level

Energy Flow  Producers—primary productivity  Gross vs. net primary productivity  Consumers—eat producers and other consumers Gross Primary Productivity (GPP)  Rate at which producers convert solar energy into chemical energy as biomass

 Varies from region to region

GPP: land—green highest, sea—red highest

 map Net Primary Productivity NPP  Rate at which photosynthesize minus the rate of respiration  NPP=GPP-R (R=energy used in respiration) NPP Productivity  Number of organisms is determined by how fast producers can supply biomass to consumers  Application—just grow more food?  Estuaries  Tropical forests  Oceans Food chains  Linked energy exchanges  Simple model

Food Web

 More complex  More interdependencies  Next figure doesn’’t show decomposers

Terms relating to trophic levels  Producers  Autotrophs  Consumers—primary secondary, tertiary  Heterotrophs  Herbivores  Carnivores  Omnivores  Scavengers  Detritivores  Decomposers Energy Pyramids

 In kilocalories per square meter per year Grand View

Matter Cycles  Fixed amount on the planet  Cycled  Biogeochemical cycles trace movement of matter through biotic and abiotic components of ecosystem

Hydrologic (Water) cycle  Traces water  Water important:  Solvent—importantimportant elementselements areare carriedcarried byby waterwater throughthrough thethe bioticbiotic elementselements  Polar–attracted to other water molecules  High specific heat—can absorb large amount of heat without changing state  Insulator Water Cycle Water Cycle  Most in oceans  Continual solar evaporation, winds distribute  Forms of precipitation support all life  Runoff to rivers, lakes, oceans  Groundwater  Living organisms—absorption, ingestion, respiration, transpiration, decomposition Carbon Cycle  2 important roles  Component of organic molecules  Energy storage in bonds Carbon Cycle  Enters bgcc with uptake through photosynthesis—atmospheric CO2

 Respiration releases CO2  Weathering of carbonate rocks  Burning of wood, grasses, fossil fuels  Carbon sinks—vegetation, oceans  Upsets in established cycle—gw, deforestation, etc.

Carbon Cycle  Can cycle quickly  Can cycle slowly  Adding fossil fuel carbon at accelerated rate Nitrogen Cycle  Essential element for life  Amino acids, proteins, nucleic acids  Plants provide N to consumers  N most abundant gas—78%  Atmospheric N is “fixed”—combined with H N Cycle  Nitrogen gas ->ammonia->nitrite->nitrate

 Nitrate (NO3) absorbed by plants  Plants change to ammonium->used to build amino acids

N Cycle—Man’’s Impact  Increase in synthetic fertilizers, nitrogen-fixing crops, fossil fuels, feed lots, factory farms (massive poultry and pork production)  Dramatic increase in N released into environment-- Pfisteiria outbreaks

Phosphorus Cycle  Phosphorus necessary for all cellular reactions  P doesn’’t exist in gaseous form  Slow cycle—water, crust, living organisms  Practically—one-way flow  Rock formations and ocean sediments  Added as fertilizer

Phosphorus Cycle  Limiting Factor—terrestrial and aquatic systems, determines # of organisms  P discharges from mining, farming and sewage treatment disrupt natural cycle

Sulfur Cycle  Essential element

 Various forms—H2S, SO2, SO4-, dimethyl sulfide, SO3, H2SO4  Sources—volcanoes, organic matter, forest fires, marine algae Sulfur Cycle  Acid rain formed from atmospheric sulfur  Acid deposition—acid rain and sulfate salt particles  Harms young plants and aquatic life  Damages materials, human health, air quality  Increased S released—burn S-containing coal and oil, refine petroleum, refine S- containing ores to metals The Sulfur Cycle Energy flows, matter cycles