A crash course in changing the world.
Pineapples are an iffy thing to farm. They're epiphytes, meaning they live on top of other things instead of planting their own roots like most plants. In forests, this means that they'll grow on the branches of various trees, trapping water in their own leaves and spines and growing in situ.
Pineapple farms, however, tend to be destructive things. The biggest ventures often rip out the top layers of soil of a given field, put down a tarp and grow the pineapples on that. When the farmers are done with the land, it is then unable to sustain anything for a long time due to the lack of soil and nutrients.
Information taken from my Tropical Forest Ecology class in University.