If cost and fuel are major concerns then sending a person is by far the cheapest option. Not the most productive but in the areas that need reforestation (i.e.

If cost and fuel are major concerns then sending a person is by far the cheapest option. Not the most productive but in the areas that need reforestation (i.e. where they burn or clear cut, Asia / Amazon) the labour is not that expensive. Though there are a lot of other factors involved. These kinds of projects remind me of Juicero, where it combines a few things western (middle/upper class?) people care about with technology and expects a great result but end up a middling disappointment.