An ecologist compares a forest and a lake…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
An ecologist compares a forest and a lake. Each makes of net primary production in each square metre in a year. In the forest, herbivores eat of it while it is alive. In the lake, the zooplankton eat of it while it is alive. The rest of each goes to the detritus food chain.
- How much goes into the detritus chain in the forest?
- How much goes into the grazing chain in the lake?
- Which ecosystem sends more energy through the detritus chain, and by how much?
Need a reminder? The key ideaShow
The grazing food chain starts with a green plant. The detritus food chain starts with dead organic matter. On land, most of the energy goes through the detritus chain. In water, the grazing chain is the major route. Joined chains make a food web.
The worked solution
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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. Total for each square metre in a year. Forest: grazed. Lake: grazed.
Plan. Grazing is the grazed share of the total. Detritus is the rest.
Step 1. (a) Forest detritus: .
Step 2. (b) Lake grazing: .
Step 3. (c) Lake detritus: . The forest sends more through the detritus chain.
Answer: ; ; the forest, by .
Check. On land the detritus chain carries more. In water, the grazing chain is the major route. The shares used here show the order only.
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