While this article does make me think twice, I still have to defend the coca farmers.
The US must destroy a lot more forest than the farmers dropping anti-foilage chemicals to stop the crops.
And I'm sure there's a reason why they don't do what tobacco farmers do. Tobacco can only be planted in the same field for two years. The old field then either goes fallow, or if it's needed the year after, a peanut crop is planted. Peanut return nitrogen and other nutrients back to the soil and it's as good as new again after one season.
Also, why would these farmers keep cutting down more forests? It really doesn't make sense that they'd just keep cutting stuff down and never replanting after the old fields go fallow for a year or two. It seems very unlikely they grow on more than a few acres. I've seen a few pictures of coca fields, and they all looked pretty small. Also, coca fields need to remain hidden. I imagine it's hard to hide a coca crop if there's an enormous area chopped out. Doesn't that seem a little obvious if you're trying to remain undetected from US drug planes? Especially planes that are dropping anti-foilage chemicals on not only your coca crop, but your food crop?
Something tells me this story is propaganda and nothing else.
Also, I cannot imagine that trees felled by coca farmers can even compare to trees felled for industrial purposes or to build roads and new cities and towns.
And at least in America, despite popular belief, the vast majority of farmers are not simply concerned with preserving farm land. They're very concerned with preserving the environment for the most part. I can't imagine farmers in Columbia would be that much different.