I remember reading years ago something to the effect that in tropical forests nutrients tend to become concentrated in the vegetation. Lush forest may be growing on nothing more than the nutrients released by decaying vegetation. If the forest is burned the nutrients fly off into the atmosphere leaving the soil impoverished. This may help explain what is happening in Central America.
Certainly if no solution can be found to feeding the population in the tropics adequately we're collectively in trouble. I'm reminded of Dean Swift's comment in "Gulliver's Travels":
'And he gave it for his opinion, that whoever could make two ears of corn, or two blades of grass, to grow upon a spot of ground where only one grew before, would deserve better of mankind, and do more essential service to his country, than the whole race of politicians put together.'
For more from that genius see:
http://www.brainyquote.com/quotes/authors/j/jonathan_swift.html
