2.3 Flows of Energy & Matter - Productivity

[Pages:41]2.3 Flows of Energy & Matter Productivity

Significant Ideas

? Ecosystems are linked together by energy and matter flow

? The Sun's energy drives these flows and humans are impacting the flows of energy and matter both locally and globally

Knowledge & Understandings

? As solar radiation (insolation) enters the Earth's atmosphere some energy becomes unavailable for ecosystems as the energy absorbed by inorganic matter or reflected back into the atmosphere.

? Pathways of radiation through the atmosphere involve the loss of radiation through reflection and absorption

? Pathways of energy through an ecosystem include:

? Conversion of light to chemical energy ? Transfer of chemical energy from one trophic level to another with

varying efficiencies ? Overall conversion of UB and visible light to heat energy by the

ecosystem ? Re-radiation of heat energy to the atmosphere.

Knowledge & Understandings

? The conversion of energy into biomass for a given period of time is measured by productivity

? Net primary productivity (NPP) is calculated by subtracting respiratory losses (R) from gross primary productivity (GPP) NPP = GPP ? R

? Gross secondary productivity (GSP) is the total energy/biomass assimulated by consumers and is calculated by subtracting the mass of fecal loss from the mass of food eaten. GSP = food eaten ? fecal loss

? Net secondary productivity (NSP) is calculated by subtracting the respiratory losses (R) from GSP. NSP=GSP - R

Applications and Skills

? Analyze quantitative models of flows of energy and matter

? Construct quantitative models of flows of energy or matter for given data

? Analyze the efficiency of energy transfers through a system

? Calculate the values of both gross primary productivity (GPP) and net primary productivity (NPP) from given data

? Calculate the values of both gross secondary productivity (GSP) and net secondary productivity (NSP) from given data

Key terms

? Gross productivity (GP) ? Gross Primary Productivity (GPP) ? Gross Secondary Productivity (GSP) ? Net productivity ? Net Primary Productivity (NPP) ? Net Secondary Productivity (NSP) ? Primary productivity ? Secondary productivity

What happens to solar radiation entering Earth's system?

3% absorbed by clouds

100% entering

solar radiation

17% absorbed by molecules & dust

49% absorbed by ground

Figure 10.1 Photoautotrophs

Only 0.06% of all solar radiation falling on Earth is captured by photoautotrophs!

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