Environmental Engineering Reference
In-Depth Information
2 Decomposers like termites and ants flourish within the continually
maintained organic debris of the forest; they quickly decompose litter on
and in the soil.
3 Micro-organisms (fungi and bacteria) thrive in the hot and humid
conditions at the soil surface, and are capable of completely removing
nutrients from the soil surface.
4 Trees have a high capacity for the uptake of nutrients through their
symbiotic relationships with a root fungus. This relationship gives
mycorrhizae (particularly the type VAM, vesicular arbuscular
mycorrhizae), and is an association of a fungus with the root of a higher
plant. They are present in most latitudes, but are particularly ubiquitous in
the tropical zone. VAM are fungi which penetrate the root in order to feed
on the cell contents. The benefit to the tree is that it is able to absorb
nutrients from the fungi, which in turn are able to extract ions from dilute
solutions such as soil water. The fungus thus acts as a nutrient pump for
the tree, and is especially important to tropical trees because they are on
old ferralitic soils (i.e. heavily leached soils with a low cation exchange
capacity). Indeed, so integrated and refined is this mycorrhizal relationship
that the fungi are often in direct contact with organic litter and can transfer
nutrients from it direct to the roots.
5 The physiology of tropical trees, especially their root systems, is such
that they have the ability to pump large volumes of water from the soil,
'filtering' it for nutrients as they do so.
