Rainforests: Way More Than Just Monkeys And Parrots, Part 2

Posted by Nick Niesen on October 29th, 2010

Rainforest deforestation impacts the planet, local and global economies. We're going to focus on the local changes, and work from there, up the chain of events and causality. The typical cycle is that rain forest lands get clear cut and used for crop lands, then cattle grazing lands when the crops fail, then abandoned (or used for housing if conveniently located), when even grazing lands fail. This is part of a vicious cycle ? most of the nutrients in a rain forest biome are tied in the living organisms, not the soil itself. When they're clear cut, and burned, most of the resulting land is poor for agricultural use, low in phosphorus and nitrates, with soil that will blow away when the first wind storm hits. Soil exhaustion and salinization from over irrigation makes things even worse. This is, in many ways, analogous to strip-mining the soil, much as one would strip mine for copper or iron ore.

In an active and thriving rain forest, minerals and nutrients cycle quickly. When the rain forest is chopped down, those nutrients aren't there any more. They're shipped off as building materials or simply burned to clear the land. When grasses are seeded for cattle ranching, the soil is already starting depleted, and gets more so quickly. Eventually, the grass gets overgrazed, winds and rains come down and wash the soil into estuaries, and the process cycles even faster.

Erosion from deforestation is an attendant problem. The cover provided by the rain forest canopy keeps the tropical sunlight from baking the moisture out of the soils, and the aspiration of the plants helps capture rain clouds and seed clouds for rain. After the forest has been cleared, rainfall drops considerably. The tropical rain forest is a perfect example of a system where the combination of elements creates a whole greater than the sum of the parts.

There are several programs in place to try to preserve rain forests; the problems come from the fact that, in terms of local economics, it's hard to convince a farmer that clearing more land to raise more crops and make more money is a losing proposition compared to leaving the rain forest in place as a refuge for vermin and predators. Trying to preserve islands of rainforest land hasn't worked; the minimum area for viable rainforest biomes is around one hundred square miles, and most of the island experiments have been a tenth of that or less. Now, larger non governmental organizations are trying to buy up large tracts of rainforest land to keep as nature preserves, or to use as a basis for ecological tourism as a revenue stream to offset land use taxes, and the economic incentives for clear cutting.

Some efforts are being put in place to teach local farmers to work with the rain forest ecosystem rather than competing with it, using clearings in the rain forest for garden plots, and attempting to harvest the bounty of the rainforest directly. These have met a great deal of resistance because of the difficulties in balancing immediate short term profit with long term sustainability.