1. Productivity

2. Assessment Standards 2.5.5: Define the terms gross productivity, net primary productivity, and secondary productivity. 2.5.6: Define the terms and calculate the values of both gross primary productivity (GPP) and net primary productivity (NPP) from given data. 2.5.7: Define the terms and calculate the values of both gross secondary productivity (GSP) and net secondary productivity (NSP) from given data.

3. Productivity The amount of organic matter or biomass produced by an individual organism, population, community or ecosystem during a given period of time. Measures in Joules (J)

4. Gross and Net Productivity Productivity can be divided into gross and net profits: Gross productivity (GP): The total gain in energy or biomass per unit area per unit time. The income. Net productivity (NP): The gain of energy or biomass per unit area per unit time remaining after allowing for respiratory losses. It is the energy left for the next trophic level to consume. The income minus the cost.

5. Primary Productivity Is the gain by producers in energy or biomass per unit area per unit time. When solar energy is converted, it depends on: the amount of sunlight the ability of the producers to use energy to synthesize organic compounds the availability of other things needed for growth, like minerals and nutrients Primary production is highest were conditions for growth are optimal, where there are high levels of insolation, good water supply, warm temperatures and high nutrient levels. Primary production is the foundation of all metabolic processes in an ecosystem, and the distribution of production has a key part in determining the structure of an ecosystem.

7. GPP and NPP Gross primary productivity (GPP): is the total amount of energy gained through photosynthesis in primary producers. Net primary productivity (NPP): is the gain by producers in energy or biomass per unit area per unit time remaining after allowing for respiratory (maintenance) losses. (Available for consumers in ecosystem) It is more useful to measure Net Primary Production (NPP). The remainder of glucose produced from photosynthesis is deposited in and around cells representing the stored dry mass(biomass). Biomass provides a useful measure of the production and use of resources. NPP = GPP – R; where R = respiratory loss.

9. Secondary Productivity Secondary productivity depends on the amount of food there is and the efficiency of the consumers turning this into new biomass. Unlike the primary productivity net productivity involves feeding or absorption.

10. Secondary Production Occurs in animals. Animals do not use all the biomass they consume. Secondary production involves feeding or absorption. Secondary production is the generation of biomass of the consumer in a system. This is driven by the transfer of organic material between trophic levels, and represents the quantity of new tissue created through the use of assimilated food. Use the equation NSP = GSP – R GSP = food eaten – fecal loss and R = respiratory loss Gross secondary productivity(GSP): is gained through absorption in consumers. Net secondary productivity(NSP): The gain by consumers in energy or biomass per unit area per unit time remaining after allowing for respiratory losses.

12. Calculate the missing values using NPP = GPP - R

13. Calculate the missing values using NSP = GSP – R GSP = food eaten – fecal loss