5.10

Give the definition and units of GPP

Gross Primary Production - the amount of chemical energy which is created from light energy in a given amount of time. Measured in KJ m-2 y-1.

Give the definition and units of NPP

Net Primary Productivity - the chemical energy stored in plant biomass after respiratory losses to the environment have been taken into account. Measured in KJ m-2 y-1

Give the definition of R

Respiration

Give the formula to show the relationship between GPP, NPP and R

NPP = GPP - R

The GPP of a grassland is 10,200 KJ m-2 year -1. The efficiency of energy transfer from GPP to NPP is 35%. Calculate the values of NPP and R

NPP - 3570 KJ m-2 y-1

R- 6630 KJ m-2 y-1

Producers have an energy intake of 14526 KJ m-2 year-1 and fix 4657 KJ m-2 year -1 as biomass. Calculate how much energy is lost via respiration.

99869 KJ m-2 y-1