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Forest
Myth-
conceptions? | | |
 SOIL
 Rainforests are
lush, therefore
their soils are
fertile?
Unfortunately, no.
Many tropical forests can grow on infertile sands,
using the soil to support the trees and quickly recycle the nutrients.
All the fertility is in the vegetation, and once removed,
the soil can be quickly degraded from excessive sun and rain.
This is why much agriculture on such soil lasts only as long
as the fertiliser made from decaying or burnt vegetation is available
– usually only a few years.
Tropical forest
soils are infertile?
Although many soils under rain forests are infertile,
once the vegetation cover is removed, there are many soils
– as in temperate lands –
that are fertile, and ideal for conversion to agriculture –
provided they are cultivated properly.
Greater care must be taken in the tropics,
because of the higher rainfall and temperature,
which can quickly destroy fertility.
Removing the tree
canopy causes
erosion?
That depends –
shrubs, grasses and leaf litter
are the most important components for protecting the soil.
They allow rain time to percolate into the soil,
and when there is too much rain, they bind the soil together
and allow water to run off without erosion.
Provided such ground vegetation is there,
or can be quickly established when trees are removed,
erosion will minimal.
Deforestation
spoils the soil?
If the soil under a forest is suitable for cultivation,
then deforestation will not spoil it,
provided removal of the vegetation is done carefully.
Care means not destroying the structure of the soil,
and allowing as much organic matter to remain and decay on the site,
so that the soil is protected from sun and rain, and subsequently enriched.
Deforestation using caterpillar tractors and similar machinery
will compact the soil and require years for recovery.
Tree planting
stops erosion?
Many mature trees have deep root systems
that help bind the lower soil.
But it is the ground vegetation
that is the most important for stopping surface erosion.
Some trees can make erosion worse.
In teak plantations,
the shade and large fallen leaves keep the soil exposed.
When the trees are mature,
their tree crowns may even form
bigger and more erosive water drops when they reach the ground,
making erosion much worse.
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