The profit is all based on lumber sales too. If profits really were that high it seems like capital would flow in until there were so many of these trees that prices would go down (though I'd imagine they're a small part of the global lumber market), especially if you can only use their wood for a limited number of things.

On the other hand, if they really do such a great job storing carbon, seems like there is potential for them to make money on the fact people are willing to pay to offset their emissions.