Non-lethal options to prevent damage caused by European beaver (Castor fiber) on managed forests

0520572 - ÚBO 2020 LT eng A - Abstract
Mikulka, O. - Homolka, Miloslav - Kamler, J. - Drimaj, J. - Plhal, R. - Skoták, V.
Non-lethal options to prevent damage caused by European beaver (Castor fiber) on managed forests.
34th IUGB Congress: Wildlife: Coexistence or Opposite? Book of Extended Abstracts. Kaunas: Institute of Forestry LAMMC, 2019. s. 157-158.
[IUGB Congress /34./. 26.08.2019-30.08.2019, Kaunas]
Institutional support: RVO:68081766
Keywords : beaver * damage * measures * oak * managed forests * management
OECD category: Ecology

The European beaver returned to the Czech Republic about thirty years ago. During this time, about two-thirds of the country's territory was settled. As population increases, the number of conflicts increases too. One of them is the damage caused by the browsing of economically valuable forests. The beaver in the Czech Republic is protected by legislation. According to the management plan the state was divided into three areas. Hunting management is permissible on one fifth of the state area. In the rest, hunting may only be allowed if there is conflict between beavers and human settlements
This study summarizes the potential for reducing forest losses in areas where hunting is forbidden. Beaver causes damage especially to oak and ash monocultures in lowland forests. These species also dominate here in diet (oak 24%, ash 17%). Within a few years, large forestless areas have been created. These areas must be re-planted, although this situation will be repeated a few years later. It is economically unprofitable in the long run.
However, beaver generally prefers willow or poplar. We focused on testing the provision of alternative tree species as food for beavers. One method would be to increase the proportion of preferred softwoods in stands that provide enough digestible and valuable biomass, which is easily grown, not economically significant, and can rejuvenate after browsing.
In order to find out the selection of tree species in the winter food centres, we made an inventory of the trees available and the tree species consumed. We did this in different stands with the same area size. It has been found that damage to economically valuable trees decreases with increasing amounts of low value softwoods. When oak dominated and there was 18% of willow within the stands, oak damage was 4 times lower than in with 6% of willow booth. The results further show that it is advisable to grow softwoods, especially willows of smaller diameters and dense stands and near the shore, for the most effective method of protection. Another effective option is to feed the branches after harvesting the trees. The fresh branches were put into localities of beaver presence. The experiment was performed in the autumn, i.e. in the time when beavers are foraging actively and making their food cache or dams. Consumption of branches of willow, poplar and ash negatively correlated with damage of surrounding forest stands. In case of branches exhaustion, the damage to the oak stands was increased.
Targeted softwood increases are more expensive and can be more difficult to grow because beaver or other game can consume trees in the early years. On the other hand, it is undemanding tree species that rejuvenate and provide permanent protection. Branches are cheap, less demanding and can be put on the currently affected areas. The disadvantages are short-term measures, and the fact that branches we have to put down annually. The success of branching attempts can be explained by the fact that beavers do not have to spend energy to fall large trees and have sufficient biomass at a safe distance from the shore. Both options seem promising and can also be a good complement to the areas where hunting management is performed.
Permanent Link: http://hdl.handle.net/11104/0305237