2.3.1 Flows of Energy and Matter

Transfer and transformation of Energy Not all solar radiation ends up as biomass. Losses include: Reflection from leaves Not hitting chloroplasts Wrong wavelength Transmission of light through the leaf Inefficiency of photosynthesis

ENERGY ENTERS THE ECOSYSTEM AS SUNLIGHT Only 2% of the light energy falling on plant is used to create energy The rest is reflected, or just warms up the plant as it is absorbed

Transfer and transformation of energy. Energy comes into the ecosystem as light energy,

Transfer and transformation of energy. Energy converted into chemical energy by producers.

Transfer and transformation of energy. That chemical energy is transferred as organisms are eaten, with energy being lost as heat and respiration.

Photosynthesis Process where plants use sun light energy to create chemical energy Photosynthesis: equation 6CO2 + 6H2O --> C6H12O6 + 6O2 Inputs: light energy, water, carbon dioxide Outputs: oxygen gas, sugar Energy transformations: Light to Chemical respiration backwards!

Respiration Process by which animals create energy through consumption of organic molecules (sugars) Respiration: C6H12O6 + 6O2 --> 6CO2 + 6H2O Inputs: oxygen gas, organic molecules (sugars) Outputs: carbon dioxide, energy in ATP, waste heat Energy transformations: chemical to heat Photosynthesis backwards!

Energy Transfers in Ecosystem CASE STUDY— California salamanders 2.1.7 Describe and explain population interactions using examples of named species. Include competition, parasitism, mutualism, predation and herbivory. Mutualism is an interaction in which both species derive benefit. Interactions should be understood in terms of the influences each species has on the population dynamics of others, and upon the carrying capacity of the others’ environment. Graphical representations of these influences should be interpreted. ESSENTIAL QUESTIONS Why do biologists say that no two species may occupy the same niche? What is the difference between interspecific and intraspecific competition? Parasites are harmful; but not too harmful. Why do most parasites not kill their hosts?   ENDGAME QUESTIONS: 1. WHAT BIG PICTURE IDEAS DO YOU NEED TO UNDERSTAND? 2. WHAT MUST YOU BE ABLE TO DO? 3. WHAT FACTS DO YOU NEED TO LEARN? ENDGAME—IB EXAMINATION REVIEW There is a menu containing the entire collection of “Essential Questions” from the various syllabus sections. Understanding these big picture ideas and being able to apply them in novel situations is the key to examination success in Environmental Sysytems and Societies. The is also a menu of “Facts and Skills” and a convenient review strategy called “Differentiations of Mastery.”  

Energy Flow Diagram

Conversion of Energy Conversation of energy into biomass for a given period of time is measured as productivity

Gross productivity Total energy captured or “assimilated” by an organism. Measured in joules (J) Plant (Gross Primary Productivity) GPP = sunlight energy used during photosynthesis Animals (Gross Secondary Productivity) GSP = food eaten - energy in faeces Energy is stored in leaf as sugars and starches, which later are used to form flowers, fruits, seeds,

Net productivity The energy left over after organisms have used what they need to survive. All organisms have waste energy and respiratory loss given off as heat, metabolism (R)

Net productivity Plants and animals have to use some of the energy they capture to keep themselves growing: They both move water and stored chemicals around Plants make flowers, fruits, new leaves, cells and stems Animals create cells and need to move muscles. Net productivity = Gross productivity - Respiration Energy or using symbols: NP = GP - R

Net Primary vs. Net Secondary Productivity (NPP) vs. (NSP) Calculate Net productivity for plants and animals NPP = GPP – R PLANTS NSP = GSP – R ANIMALS NSP GSP

Productivity Primary Productivity – gain by autotrophs in energy or biomass per unit area per unit time

Productivity Secondary Productivity – biomass gained by heterotrophs thru feeding and absorption, measured in units of mass or energy per unit area per unit time

Productivity Gross Primary Productivity – Gain in energy or biomass thru photosynthesis per unit area per unit time.

Productivity Net Primary Productivity – The gain by producers in energy or biomass per unit area per unit time remaining after respiration losses.

Productivity Gross Secondary Productivity (Gross Assimilation) – Gain in energy or biomass thru absorption per unit area per unit time.

Productivity Net Secondary Productivity (Net Assimilation) – The gain by consumers in energy or biomass per unit area per unit time remaining after respiration losses.

Productivity in Food Web In a food web diagram, you can assume that: Energy input into an organism represents the GP Energy output from that organism to the next trophic level represents the NP GP-NP = R (respiration energy ) and/or loss to decomposers ?

Therefore… The least productive ecosystems are those with limited heat and light energy, limited water and limited nutrients. Example biome:_______________ The most productive ecosystems are those with high temperature, lots of water light and nutrients. Example biome:__________________

How to measure primary productivity Harvest method – measure biomass and express as biomass per unit area per unit time. CO2 assimilation- measure CO2 uptake in photosynthesis and releases by respiration O2 production-Measure O2 production and consumption

Measuring productivity continued 4.Radiosotope method-use c14 tracer in photosynthesis. 5.Chlorophyl measurement- assumes a correlation between the amount of chlorophyll and rate of photosynthesis.

Complete this energy flow diagram: Label GPP, NPP and R for the primary producer Add arrows to show missing energy pathways (5 in total) Fill in the blank box to explain why some sunlight is not fixed by plant SUN PLANT DECOMPOSERS RESPIRATION ……………………………. (~98% of energy is here) HERBIVORES

Respiratory loss by decomposers The data in the table below relate to the transfer of energy in a small clearly defined habitat. The units in each case are in kJ m-2 yr-1 Trophic Level Gross Production Respiratory Loss Loss to decomposers Producers 60724 36120 477 1° Consumer 21762 14700 3072 2° Consumer 714 576 42 3° Consumer 7 4 1 Respiratory loss by decomposers --- 3120 Construct an energy flow model to represent all these data – Label each arrow with the appropriate amount from the data table above. Use boxes to represent each trophic level and arrows to show the flow of energy Calculate the Net Productivity for NPP for Producers NSP for 1°Consumers, 2°Consumers, 3°Consumers NSP for Decomposers

ENERGY FLOW MODEL Producers 1 Consumer 2 Consumer 3 Consumer 60724 21762 714 7 Producers 1 Consumer 2 Consumer 3 Consumer 3072 42 477 1 Decomposers R=3120

Productivity Calculations NPP of Producers: 60724 - (36120+477) =24127 kJ.m-2.yr-1 NSP of 1 Consumer 21762 -(14700+3072) =3990 kJ.m-2.yr-1 NSP of 2 Consumer 714 -(576+42) =96 kJ.m-2.yr-1 NSP of 3 Consumer 7 -(4+1) =2 kJ.m-2.yr-1 NSP of Consumers: 22483 -(15280+3115) =4088 kJ.m-2.yr-1 NSP of Decomposers: (477+3072+42+1) -3120 =472 kJ.m-2.yr-1