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Termites

  • Termites interfere with many soil-forming processes that take place in tropical regions through
    1. nest-building

       
      Fig.1 Termite mound Nigeria
      ( Source: Prof. Horst Fölster, Göttingen.)

    2. enhancing soil horizon formation by mixing or sorting soil constituents, i.e. relocation of material: clay migration and formation of a textural gradient, and
    3. decomposition of SOM
  • Termites have no carapace (panzer) and are prone to desiccation (construct tunnels) and therefore build tunnels. They collect fresh and old plant materials, often as far as 50 m away from their nest. They can collect up to 3800 kg per hectare (~ 25 % of the total leaf fall) (Fölster, personal communication).

     
    Fig.2 Termite mounds and tunnels
    ( Source: Prof. Horst Fölster, Göttingen.)

  • Termites bring fine soil material (0.5 bis 2 mm) to the surface together with moisture leading to the formation of a textural gradient. The diameter of the particles that termites transport is limited by the maximum size they can carry in their mandibles. Generally, no gravel size grain can be transported.

     
    Fig.3
    ( Source: Prof. Horst Fölster, Göttingen.)

  • Termites dig into subsoil horizons and constantly bring new materials to the surface. The amount of fine soil material (0.5 bis 2 mm) displaced from the sub-soil to the surface can be as high as 300 to 1000 kg/ha/year (corresponding to 0.02 to 0.1 mm/year; Nye, 1955). At the surface the impact of raindrops disrupts the aggregates and detaches clay from them. Clay is removed as a suspension by runoff water to the valleys leaving behind the coarse sand particles.
  • Nye (1955) calculated that the mounds of Macrotemes bellicosus on soils derived from gneiss near Ibadan, Nigeria could account for the accumulation of a 30 cm surface mantle above the stone-line. The time required for the accumulation was estimated at 12.000 years.
  • A close correlation of the mineralogy of the sand fraction in the surface soil and underneath in the stone line would acknowledge this theory.