Energy Flow in Ecosystems File

Energy Flow In Ecosystems BIG IDEA:

WHAT HAPPENS TO ENERGY STORED IN BODY TISSUES WHEN ONE ORGANISM EATS ANOTHER?

Food Chains & Food Webs  How does energy flow

through ecosystems? 

A 1-way stream, from primary producers to consumers

 Food Chains  A series of steps in which organisms transfer energy by eating and being eaten

Food Chains & Food Webs  Food Webs  A network of feeding relationships; shows all the feeding relationships within an ecosystem

Food Chains & Food Webs  Food Webs –  Very complicated 

Notebook Time: Describe the ecosystem that is your backyard  Draw a food web of that ecosystem  Be as specific as possible  Draw a food chain from within your food web  What role do decomposers & detritivores play in food webs? 

Food Chains & Food Webs  Disturbances  In your groups, answer the following questions using the food web below: What effect would an insecticide have on the food web?  Would this have an effect on the populations of non-insect eating animals?  What populations would increase?  What populations would decrease?  Would this change any animals eating habits? Which ones & how? 

Trophic Levels & Ecological Pyramids  Trophic Level  Each step in a food chain  Ecological Pyramids  Show relative amount of energy or matter contained within each trophic level in a given food chain or food web  There are 3 different types of Ecological Pyramids Pyramids of Energy  Pyramids of Biomass  Pyramids of numbers 

Ecological Pyramids  Pyramids of Energy  Show relative amounts of energy available at each trophic level  Typically 1/10 or 10% of available energy within one trophic level is passed on to the next level  In other words:  1/10 of the solar energy captured and stored in leaves of grasses ends up stored in the tissues of cows 

Ecological Pyramids  Pyramid of Biomass &

Numbers 

Biomass – 



Total amount of living tissue within a given trophic level

Pyramid of Biomass 

Illustrates the relative amount of living organic matter available at each trophic level of an ecosystem

Ecological Pyramids  Pyramid of Biomass &

Numbers 

Pyramid of Numbers 

Shows the relative number of individual organisms at each trophic level in an ecosystem

Cycles of Matter  How does matter move through the biosphere? 

Biogeochemical cycles Elements pass from one organism to another and among parts of the biosphere in closed loops  These loops are powered by the flow of energy. 



4 Processes involved with biogeochemical cycles Biological Processes  Any and all activities performed by living organisms  Geological Processes  Volcanic eruptions, erosion, plate tectonics  Chemical & Physical Processes  Formation of clouds, flow of running water, lightning  Human Activity  Deforestation, burning of fossil fuels, use of fertilizers 

Water Cycle Water moves continuously between, oceans, the atmosphere, land and the organisms in them.  Transpiration 

Evaporation of water from leaves of the plants

 Evaporation  Loss of water from surface of bodies of water  Condensation  When water vapor cools & becomes liquid  Precipitation  When water falls out of the atmosphere

Nutrient Cycles  3 main Nutrient Cycles  Carbon  Nitrogen  Phosphorus

Nutrient Cycles  Carbon Cycle  Found in several large reservoirs in biosphere Atmosphere = CO2  Oceans = Dissolved CO2  Land = in organisms, soil & rocks  Underground =  Coal, Petroleum & Calcium Carbonate  In Life = base of all organic molecules 

Nutrient Cycles  Nitrogen Cycle  

Required to build proteins, DNA, RNA Atmospheric Nitrogen 

N2 = Non-usable form for most organisms  Needs to be “fixed”  Nitrogen Fixation • Process of N2 being converted into ammonia, nitrates & nitrites by bacteria • Relatively small amounts of N2 can be fixed by Lightning 

Denitrification • When N2 is released by soil bacteria who use nitrates for energy



Fertilizer 

Huge human influence in adding excess Nitrates & Nitrites into aquatic ecosystems  Can cause algal blooms

Nutrient Cycles  Phosphorus Cycle  Essential for creation of DNA, RNA  Not very abundant in biosphere 



Remains mostly on land in rock, soil, & sediments

As rock & sediments wear down, P is released to environment.

Nutrient Cycles  Nutrient Limitation  Limiting Nutrient 

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In Soil 



The nutrient whose supply limits productivity

Typically Limiting Nutrients are:  Ca, Mg, S, Fe, Mn, P, Fixed N,

In Ocean 

Typically Limiting Nutrients are:  Fixed N