The beaver cuts down the trees across the banks for feeding on their bark and in summer, their leaves and buds. 60% of   its fellings occur within 5ms from water.

 

 Without the beaver,  the trees grow up to their climax and close again in the aquatic surroundings   where their corona rises above all others. By doing this, they reduce the quantity of light that leads to the aquatic environment. The beaver while cutting down the trees, maintains the balance between the forest and the river. In fact, it thins out the valley deeps,  the light gets in again the aquatic surroundings in favour of the successive developments of planktons, on which fishes and batrachians both feed, then kingfishes feed on fishes and, finally herons and storks for fishes as well as batrachians.

 

Without the beaver, the trees close again in the aquatic surroundings until swept along by their heaviness, fall into water, uprooting all the river bank. Each year, hundreds of trees fall into rivers of Wallonia. The beaver by its felling labour, replace the trees stratum with high stems (more often inclined towards water) by a shrub stratum (it is formed by shrubs, bushes which represent a small weight in comparison with their mass of roots). This shrub stratum as shown clearly several times, protect properly the banks against erosion.   The pruning of softwoods' trunks and branches  at the bottom of river bank allow maintaining  fine and supple stems to the touch of  the strongest hydroelectric powers.  The rapidity of uprooting is thus largely reduced as well as its force. Thereby, materials carried hanging up in water (clays, muds and sands) settle on the bed of the stream .So, this phenomenon reinforces the soils' stability so that these semi-aquatic plants "helophytes" and new roots of willows may develop in optimal conditions.

 

The "ripisylve" or "la forêt rivulaire" (the  forest of river bank maintained by the beavers) protects the soils, in particular, the agricultural soils against erosion by washing (precipitations). Without the beaver, some trees of "ripisylve", when it exists, topple over in water and create erosion points of banks and soils.

 

The liquid manures washed by rain, are purified by root transit of the "ripisylve" maintained by the beaver before getting in the river. The "ripisylve" is the purification station for farmers.