Despite these problems, however, there are now enough studies to allow a clearer picture to be formed. Until recentlly, it was believed that nearly all the mineral nutrients in tropical rainforests are held in the biomass above-ground. This is certainly the case for the soluble cations of Potassium , Calcium , and Magnesium in the Brazilian forest, but not entirely so elsewhere. What does seem to be true is that the positioning of the roots, which varies in different soils, is such that the nutrients are captured by them before they are washed out of the soil. The main flows of nutrients are shown in this diagram, using the example of a lower montane rainforest in New Guinea.
Coarse litter can differ a great deal according to where and when it is collected.
There is often much more coarse litter than fine litter. After the litter has decomposed, the nutrients from it pass into the mineral soil and may be taken up by the roots or washed out into streams. Nutrients may also get into the soil from the breakdown of soil minerals. Most of the plant roots are in the top 0.1 to 0.3 metres of the soil . This layer of roots is important for taking in nutrients which enter the soil surface.