system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why can't we repopulate lands and deserts with trees with all the technologies we have available these days?

We always hear about deforestation and how there are so much barren wastelands everywhere. With the ability to transport water and other necessary things and technology, isn't it possible to repopulate a dessert or land that has been harvested?
gpt
We can, but it is expensive and would have a lot of other effects that we don't want. For example, sand blowing across the ocean from the Sahara is responsible for replenishing the soil of the Amazon. So, even if we can, it might not be a good idea.