Question

In a terrestrial (land) ecosystem, 3,000,000 kJ of energy is produced by trees. 1,000,000 kJ of energy is used by the trees in respiration. 100,000 kJ of energy is transferred to the insects. 8,000 kJ of energy is transferred to birds.

a) Determine the GPP and NPP of this ecosystem.
b) Calculate the percentage of energy transferred to the insects.
c) Calculate the percentage of energy lost in transfer to the insects.
d) Calculate the percentage of energy transferred from the insects to the birds.
e) Calculate the percentage of energy lost in transfer to the birds.

Answer 1

The GPP of the ecosystem is 3,000,000 kJ, and the NPP is 2,000,000 kJ. 5% of the ecosystem's NPP is transferred to insects and 8% of energy is transferred from insects to birds, indicating an ecological efficiency of 5% and 8% respectively at each trophic level.

Step-by-step explanation:

The Gross Primary Productivity (GPP) of an ecosystem is the total amount of energy produced by primary producers, such as trees. The Net Primary Productivity (NPP) is the energy that remains after primary producers have used some of this energy for their own processes, like respiration.

a) In this terrestrial ecosystem, the GPP is 3,000,000 kJ because that's the total energy produced by the trees. The NPP is 2,000,000 kJ, calculated as GPP (3,000,000 kJ) minus the energy used by trees in respiration (1,000,000 kJ).

b) The percentage of energy transferred to the insects is (100,000 kJ / 2,000,000 kJ) * 100 = 5%.

c) The percentage of energy lost in transfer to the insects is 100 - 5 = 95%.

d) The percentage of energy transferred from the insects to the birds is (8,000 kJ / 100,000 kJ) * 100 = 8%.

e) The percentage of energy lost in transfer to the birds is 100 - 8 = 92%.