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Trente ans de lutte contre l’onchocercose en Afrique de l’Ouest. Traitements larvicides et protection de l’environnement

 | 
Laurent Yaméogo
, 
Christian Levêque
, 
Jean-Marc Hougard

Environmental Impact Assessment of Settlement and Development in the Upper Léraba Basin

Annex 2. Summary of the Regulative Functions of Riverine Forests

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Arboreous component

1The sheer size of the trees and the compactness of the forest canopy reduce the direct impact of solar radiation onto the surface of the river and the river bank, which has four beneficial effects:

  • helps to maintain river water at the temperature which is optimal for the aquatic fauna and flora,
  • contributes towards the maintenance of an appropriate level of dissolved oxygen in the water,
  • reduces the evaporation rate of the river water,
  • assists in maintaining optimal temperatures and relative humidifies in the understory part of the forest, thus creating ideal habitats and refugia for many animal species; both invertebrates (including important insect predators and parasites) and small vertebrates (especially birds, small mammals and reptiles).

2Fall-out of organic debris (leaves, bark, flowers and fruits) and other biological material (terrestrial invertebrates, especially insects), provides organic nutrients, upon which fish and aquatic invertebrates are directly or indirectly dependent.

Subterranean component

3The concentrated mesh of root Systems has two main functions:

  • it provides physical stability to the river bank, which prevents bank erosion and protects the adjacent floodplain,
  • it filters ground water that seeps from the savanna into the river, and by so doing, retains nitrates, other inorganic compounds and some organic agrochemicals.

© IRD Éditions, 2003

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