- An example of managing / maintaining the number / the use of something is replacing that something
- Resources must be managed
- Therefore, an example of managing the number of a resource is replacing that resource

- Trees are a kind of resource
- A forest contains lots of plants / trees
- Hence, trees are a kind of resource in a forest

- An example of managing the number of a resource is replacing that resource
- Trees are a kind of resource in a forest
- Therefore, an example of managing the number of trees in a forest is replacing those trees

- An example of managing the number of trees in a forest is replacing those trees
- A tree can be replaced by planting a new tree each time one is cut down
- Therefore, an example of managing the number of trees in a forest is replacing trees by planting a new tree each time one is cut down

- An example of managing the number of trees in a forest is replacing trees by planting a new tree each time one is cut down
- Timber companies cut down trees
- So, timber companies can manage the number of trees in a forest by planting trees to replace what they cut down

So, timber companies can manage the number of trees in a forest by planting trees to replace what they cut down
Question: Timber companies can best manage the number of trees in forests by
Context: - Timber companies cut down trees 
- An example of managing / maintaining the number / the use of something is replacing that something 
- Resources must be managed 
- Trees are a kind of resource 
- A forest contains lots of plants / trees 
- A tree can be replaced by planting a new tree each time one is cut down