- A plant requires nutrients to grow
- Soil contains nutrients for plants
- Therefore, plants use the nutrients in soil to grow

- Using resources decreases those resources
- Nutrients are a kind of resource
- Hence, using nutrients decreases those nutrients

- Plants use the nutrients in soil to grow
- Using nutrients decreases those nutrients
- So, plants can decrese the nutrients in soil

- A rainforest is a kind of forest
- A forest contains lots of plants / trees
- Hence, a rainforest contains lots of plants

- Plants can decrese the nutrients in soil
- A rainforest contains lots of plants
- Hence, the soil in a rainforest can be low in nutrients

Therefore, the soil in a rainforest can be low in nutrients
Q: Rain forests contain more species of trees than any other biome. However, scientists have found that the soil of the forest floor is relatively nutrient poor. What could most likely account for this?
Context:
- A rainforest is a kind of forest 
- Using resources decreases those resources 
- A plant requires nutrients to grow 
- A forest contains lots of plants / trees 
- Soil contains nutrients for plants 
- Nutrients are a kind of resource