The influence of vegetation on soil Vegetation also influences soil in a number of ways:
Plant litter • Vegetation provides the plant litter to make humus. Brown earth soils formed under deciduous forests are rich in humus and fertile. Podzol soils formed under coniferous forests are infertile.
Soil erosion • Vegetation binds the soil and protects it from soil erosion and mass movement. When this cover is lost, the soil is vulnerable and erosion occurs.
Leaching • Vegetation acts as an umbrella and reduces the impact of heavy rain on the soil. This reduces the effects of leaching. Where leaching does occur, in areas such as the tropical rainforests, some trees have very shallow roots to access the minerals in the A horizon before they are leached down through the soil.
( Figure 16.16 Soil erosion due to lack of vegetation cover
) Figure 16.17 Vegetation being used to prevent erosion or a landslide on a steep bank
(i) Explain the term ‘natural vegetation’. (ii) How do farmers deal with soil that is too acidic? (iii) Explain how vegetation cover reduces the rate of leaching and soil erosion.
/ I understand how soil and vegetation influence each other. 294
