Ecological Ecological pyramids and pyramids and productivityproductivity

ActivitiesActivities

Complete first and second page of Zoo Complete first and second page of Zoo assignmentassignment

Complete food chain and food web sheetComplete food chain and food web sheet

Ecological pyramidsEcological pyramids

Represent trophic levels in an ecosystemRepresent trophic levels in an ecosystem Do not show specific eating relationshipsDo not show specific eating relationships Detritivores and decomposers usually Detritivores and decomposers usually

omittedomitted The length of the bar at each level of the The length of the bar at each level of the

pyramid shows the relative measurement pyramid shows the relative measurement of the trophic level in terms of numbers, of the trophic level in terms of numbers, biomass or energybiomass or energy

Pyramid of numbersPyramid of numbers

Shows number of organisms at each Shows number of organisms at each trophic level per unit area of ecosystemtrophic level per unit area of ecosystem

Pyramid shaped is the most common, but sometimes the shape may be inverted or spindle shaped

Pyramid of biomassPyramid of biomass

Biomass is the amount (weight) of dry Biomass is the amount (weight) of dry organic matter at a trophic level at a organic matter at a trophic level at a particular timeparticular time If biomass is

measured only over a short period of time, pyramid may be inverted, as higher level organisms often take longer to build up biomass

Pyramid of energyPyramid of energy

Shows amount of energy INPUT into Shows amount of energy INPUT into each trophic leveleach trophic level

Never inverted. (why?) Never inverted. (why?)

ActivitiesActivities

Glossary: Ecological pyramid, biomass, Glossary: Ecological pyramid, biomass, pyramid of numbers, pyramid of biomass, pyramid of numbers, pyramid of biomass, pyramid of energypyramid of energy

Quick check pg 454Quick check pg 454

ProductivityProductivity

Rate at which chemical energy is Rate at which chemical energy is produced in an ecosystemproduced in an ecosystem

Expressed in units such as “grams of Expressed in units such as “grams of organic matter per square metre per organic matter per square metre per year”year”

Production: gross and netProduction: gross and net Gross Primary Production (GPP) = Gross Primary Production (GPP) =

chemical energy produced over a given chemical energy produced over a given period of timeperiod of time

R = energy that is used by the producers R = energy that is used by the producers within their lifetime within their lifetime

Net Primary Production (NPP) = amount Net Primary Production (NPP) = amount of energy available to consumersof energy available to consumers

NPP = GPP - R

In general, those ecosystems with the In general, those ecosystems with the highest net productivity are those with the highest net productivity are those with the greatest producer biomassgreatest producer biomass

More producer biomass

More photosynthesis

More chemical energy stored in organic matter

Other limiting factors of productivity:Limiting factorLimiting factor Why it limitsWhy it limits

TemperatureTemperature Low = slower enzyme activityLow = slower enzyme activity

SunlightSunlight Low = little radiant energy to convertLow = little radiant energy to convert

NutrientsNutrients Low = stunted growth of producersLow = stunted growth of producers

Water availabilityWater availability Low = no growth of producersLow = no growth of producers

Deep sea ecosystemsDeep sea ecosystems

May survive on organic matter that floats May survive on organic matter that floats down from surface-dwelling organismsdown from surface-dwelling organisms

Few organisms live at these depthsFew organisms live at these depths

ChemosynthesisChemosynthesis

No light = no photosynthesisNo light = no photosynthesis Chemosynthesis = bacteria use chemical Chemosynthesis = bacteria use chemical

reactions occurring at sea vents to reactions occurring at sea vents to produce organic matterproduce organic matter

ActivitiesActivities

Glossary: productivity, gross primary Glossary: productivity, gross primary productivity, net primary productivity, productivity, net primary productivity, chemosynthesischemosynthesis

Quick check pg 458, pg 460Quick check pg 458, pg 460