Relation between properties and age of soils in the Amazon forest
The Amazon Basin is that part of South America drained by the Amazon River and its tributaries. It has a tropical climate with an annual rainfall of 1500-2500mm, and a day temperature of 30-35 degrees Celsius (Wikipedia). Much of what we now know about tropical soils was derived from many years of research in the Amazon rainforest. It is now widely known that this very important rainforest is growing on largely infertile and highly wethered soils called Ferralsols in the IUSS World Reference Base classification or Oxisols in the USDA Soil Taxonomy (see photo of typical soil profile). It has been suggested by some ecologists that the efficient nutrient cycling and the periodic dust deposition from Africa explain why the infertile soils are able to support the lush rainforest vegetation. In the recent issue of the international journal Biogeosciences Discussions, Quesada and colleagues reported the results of their interesting study on the soils in the Amazon Basin. Highlights of their f