Tropical Soil Depletion

Tropical soils across the world have a problem with nutrient depletion. Nutrients are removed from the soil without being replenished. There does not seem to be the same trouble in temperate zones.

There is a Wikipedia article concerning this, just enter in "fertility (soil)" on http://www.wikipedia.org/ . The article has a section entitled "Soil Depletion". Articles on tropical soil depletion will also come up in a Google search.

I would just like to add my observation to this phenomenon. One of the major differences between temperate and tropical zones is that leaves fall from the trees in the temperate zones, but not in the tropical zones. It is very true that population density in the tropics is part of the problem, but falling leaves carried by the wind redistribute nutrients each autumn in temperate zones, but not in the tropics. This annual nutrient redistribution may be vital to preventing the soil depletion which occurs in the tropics.

I cannot say for certain if anyone else has thought of this, but I did not see it mentioned in any of the online articles that I read about tropical soil depletion.

The falling of leaves serves another purpose in that is saves the branches of the tree from supporting the weight of heavy snow. In the autumn of 2006, heavy snow fell in Buffalo, NY before the leaves had fallen from the trees and the result was the destruction of countless trees. I came out of work that evening and could hear the sound of snapping tree branches coming from all directions.

Leaves are light enough to be easily carried by the wind and the thin leaves do not take long to degrade back into nutrients. Most leaves do not travel far from the tree on which they grew, but the process is repeated every year and the result is a very effective process for redistribution of nutrients. Flowing water carries leaves that fall into it from higher to lower ground, but this process serves to reverse this and return nutrients to the higher areas.

Nutrients in the soil are gradually depleted by growing plants, but this continuous redistribution returns nutrients to those areas of ground where they have been depleted. Most of the structure of plants comes from carbon taken from carbon dioxide in the air, but nutrients from the soil are also essential for plant growth.