Some tropical rain forests have soil that is very rich in nutrients. These soils have a high nutrient content because many organisms die and other organisms help them decompose and return to the soil. These "decomposers" include bacteria, insects and, most importantly, fungi. Fungi are the only organisms capable of breaking down the cellulose found in plant material, which allows the fungi to return the cellulose back to the soil. The cooler the surface ground, the slower decomposers can reduce plant material into the soil. Rich soils cause abundant plant growth, which attracts a broad range of animals, unlike the more infertile soil found in tropical rainforests. While there is less diversity, there is a larger quantity of life forms in the temperate rain forests.
Soil on the forest floor of the temperate rain forests is dark and moist. The reason why this soil has greater richness than tropical rainforests stems partly from the types of trees found there. The trees in tropical rainforests tend to create large mats of roots that can effectively spread out and collect all of the nutrients that accumulate on the forest floor, rapidly leaching the nutrients away. Temperate rainforests have less biodiversity and thus have not developed plants that engage in this behavior. But temperate rain forest trees do try to place their roots over the roots of their competitors, often effectively starving them of nutrients.
Timber operations and slash-and-burn farmers destroy temperate rainforest ecosystems by stripping away essential plants. These plants prevent soil erosion both by blocking wind and by holding the soil in place with their roots. Soil erosion causes the loss of many nutrients, which disrupts and gradually destroys ecosystems, as plants can no longer grow and animals can no longer find food.
"Nurse" logs on the forest floor act as soil for many new plants. These plants grow in the nurse logs, which provide the plants with a source of nutrients. These nurse logs keep the plants away from the forest floor, which has many foraging animals and greater competition among plants. Gradually, trees sprout out of the decaying nurse logs.