A model ecosystem has a gross primary productivity of 12000 kJ in each square metre in a year…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A model ecosystem has a gross primary productivity of in each square metre in a year. Its plants lose of it in respiration. Then of the energy passes on at each step.
- What is the net primary productivity?
- How much energy is there at T3, taking the NPP as the energy at T1?
- How much energy is there at T4?
Need a reminder? The key ideaShow
. The NPP feeds the grazing chain and the detritus. At the energy at T3 is . In a steady ecosystem, the heat that leaves equals the GPP.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. GPP . Respiration . passes on.
Plan. Find the NPP. Then multiply by for each step.
Step 1. (a) is lost. .
Step 2. (b) T2 . T3 .
Step 3. (c) T4 .
Answer: ; ; .
Check. The energy at T3 is one hundredth of the NPP.
Watch out. Starting from the GPP instead of the NPP gives a wrong answer.
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