| Tropical rainforests, surprisingly, contain some of the poorest soils of all. This is because of the torrential rains that fall regularly on these regions. The heavy rains dissolve nutrients in the soil, which then wash into streams and rivers and are carried away. | In coniferous forests, the litter layer is made up of tough, dry needles and fallen twigs. This layer doesn't decompose easily, and remains on the ground for many years. Usually small fires burn off the fallen needles before they can decompose. |
 After an area of forest is clear-cut, it is often burned. This destroys nutrients in the soil, as well as the "litter layer" of partially decomposed leaves and branches. Photo by Al Walters. |
| In temperate deciduous forests, soil is usually relatively rich. This is because every fall, the trees drop the leaves that they grew the previous spring. This vast amount of organic material contributes to the "litter layer" on forest soils. The fallen leaves are a great food source for the fungi and bacteria in the soil. These creatures slowly help the leaves to decompose, and they are eventually turned back into soil which the trees can use to grow new leaves in future seasons. The material at the top of the litter layer is newly fallen and recognizable. Towards the bottom, the older leaves are torn and usually covered with a slimy coating of microorganisms which feels gross, but it's vital to returning nutrients to the soil. |
soil types -- page 3 of 4
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[tropical forests] [coniferous forests] [temperate forests] [water] [fungi]
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