The beaver – a landscape designer has returned
During a walk in the Bruchriede area in Rethen, visitors cannot fail to notice them:
Gnaw marks, felled trees, waterlogged areas and dams holding back the water.
Who is responsible for this?
The beaver. It is an active creator of its own habitat.
Why did it settle here?
There are several reasons for this:
· The Bruchriede and the flood basin have plenty of water. If there is too little water in summer, the beaver builds dams. This regulates the water level of the stream.
· In addition to the water, there is a sufficient amount of food, including herbaceous plants and softwoods whose bark the beaver feeds on during the winter months.
· The territory was unoccupied. If another beaver was already living here, a territorial fight decided who would occupy it.
Why do beavers build dams?
Certainly not out of boredom
The beaver needs a water depth of at least 60 cm. Then it can swim well and the entrance to its lodge will be under water. If these conditions are met, the beaver refrains from putting its energy into building dams.
Sometimes, however, the beaver also builds dams for the sake of ‘convenience’.These "feeding dams" allow it to reach corn or beet fields by swimming and then transport its harvested supplies by water.
What are the positive consequences of a beaver dam?
Beaver dams are very stable structures.They hold back the water and change the river dynamics. This can help mitigate flooding. The water flows away more slowly and flood peaks are reduced.
Beaver dams raise the groundwater level.The water is held back, it seeps away more slowly on larger water surfaces and groundwater forms. This is very valuable in periods of drought.
Overflowing of the stream leads to waterlogging in the neighbouring areas.This results in the creation of wetlands and sometimes even a beaver pond.
What are the benefits of wetlands and beaver ponds?
These areas create different habitats for a variety of plant and animal species.
They are important breeding grounds for birds. Habitats for amphibians, insects, dragonflies and fish species, as well as food sources for many types of animals.
The ponds and wetlands created by beavers act as natural filters that remove sediment and nutrients from the water.
This improves water quality and promotes the growth and colonisation of plants that live entirely or partially in the water.
Biodiversity increases dramatically in and around beaver ponds and wetlands.
Why do beavers fell trees?
Out of hunger and because they cannot climb.
When a beaver can no longer find herbs and other plants in the cold season, it eats the nutritious bark of a tree and its branches. It uses the gnawed branches and thinner trunks to build dams or to make its lodge winterproof.
Why is there no danger to the tree population?
The beaver lives in its territory for the rest of its life. Therefore, it only fells as many trees in winter as it needs for food. Most of the trees it fells are willows with a diameter of less than 5 cm. These grow back within a year.
What benefit do the felled trees have for nature?
Felled and debarked tree trunks die and become deadwood over time. This provides new habitats and food for small mammals, rare bird species, amphibians, dragonflies, insects, fungi and mosses.
Trees lying in water swirl the water, enriching it with oxygen.
The branches of the tree lying in the water and the algae that adhere to them over time provide fish with breeding grounds, food and hiding places.
The felling of trees creates clearings. More sunlight reaches the ground. This promotes the growth of young trees and shrubs. New plants can colonise and biodiversity increases.
Why is the beaver described as a keystone species?
The beaver is labelled as such because it creates new habitats for many animal and plant species through its construction activities and the associated changes to the landscape.
Many endangered species that depend on wetlands benefit from the newly created habitats. This contributes to the recovery and reintroduction of such species, thereby increasing biodiversity.
Why can conflicts arise in beaver territories?
Dam construction activities can lead to waterlogging and flooding of agricultural land. Agricultural machinery can no longer drive over these areas. Seeds, arable crops and meadows can be surrounded by or under water, and waterlogging can lead to crop failures.
Beavers can block drainage ditches and canals. This makes it difficult to cultivate land and can jeopardise infrastructure.
Beavers are unable to distinguish between crops, such as maize, beetroot and apple trees, and wild plants. This may result in damage to crops and valuable trees.
Flooding can occur near settlements. Gardens and other private plots of land can become waterlogged. As a result, some residents rightly worry about their cellars not remaining dry.
The beaver's digging activities can undermine farmland, riverbanks and infrastructure. Paths can sink and machinery can break down.
As a result of dams and ditches, nearby roads, paths and railway networks can be undermined or flooded.
The felling of trees can pose a danger to passers-by if they are close to footpaths or cycle paths.
What can be done to resolve these conflicts?
In the event of a conflict, please contact the ÖSML (Ökologische Station Mittlere Leine) in Laatzen-Grasdorf. They will advise you and inform you about potential solutions. The Untere Naturschutzbehörde der Region Hannover (Nature Conservation Authority of the Hannover Region) will decide whether conflict resolution measures are necessary.
What should you not do?
Take action yourself.
Beavers are strictly protected under the German Federal Nature Conservation Act.
It is forbidden to stalk, catch, disturb, injure or kill them. It is also forbidden to damage or destroy their lodges and dams.
Anyone who violates this law is committing a criminal offence and will be fined. The amount of the fine varies depending on the federal state. In Lower Saxony, fines of up to €50,000 can be imposed.
https://www.bussgeldkatalog.org/tierschutz-biber/