In a model forest, the tree layer takes 85% of the light that falls on it…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
In a model forest, the tree layer takes of the light that falls on it. The shrub layer takes of the light that reaches it. Take the light above the trees as .
- What per cent of the light above the trees reaches the herb layer?
- A storm breaks some branches, and the tree layer now takes only . The shrub layer still takes . What per cent reaches the herbs now?
- Which layer gains the most from the gap? Give the answer as a number of times: how many times more light do the herbs get?
Need a reminder? The key ideaShow
An ecosystem has an abiotic part (water, light, temperature, soil, nutrients) and a biotic part (producers, consumers, decomposers). The species sit in layers, which is called stratification. In a forest the layers are the trees, the shrubs, and the herbs and grasses.
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. Tree layer takes , then . Shrub layer takes .
Plan. The light that passes a layer is of what falls on it.
Step 1. (a) Under the trees: . On the herbs: .
Step 2. (b) Under the trees: . On the herbs: .
Step 3. (c) times. The herbs get twice the light.
Answer: ; ; times.
Check. A thinner tree layer lets more light through, so the herbs gain.
Watch out. The shrub layer takes a share of the light that reaches it, not of the original .
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