“Protecting the climate and protecting biodiversity mustn’t be played off against each other”
The energy transition and the effects it is having on biodiversity are often the subject of controversial and emotional discussions. But this need not be so, says Prof. Sascha Buchholz. He heads the Animal Ecology research group at the Institute of Landscape Ecology at the University of Münster, and one of the things he is researching into is spatial and temporal changes to biodiversity. In his work, he looks at a broad spectrum of different species of fauna and flora. Taking bats as an example, Kathrin Kottke spoke to him about the ways in which the challenges of protecting nature and protecting species can be reconciled with the expansion of renewable energies.
Why are wind turbines dangerous for bats?
Bats often fly at altitudes at which the blades of wind turbines rotate. This is why there is a danger of bats colliding with these rotor blades and being injured or killed. Moreover, bats react very sensitively to changes in pressure. The rapid rotation of the blades produces negative pressure, which can damage a bat’s lungs. Building wind turbines destroys or adversely affects bats’ habitats and, as a result, the areas in which they hunt and reproduce may be disturbed.
The prerequisite for giving up fossil energy sources is having the space for alternative sources, for example for the increased use of wind, solar and bioenergy – for which very large areas are needed on land or on the water. This often has a negative impact on flora and fauna, as well as on so-called ecosystem services.
Can you give a specific example?
Bats make a decisive contribution to the balance in many ecosystems: they are, for example, effective insectivores and help to control the insect population; this is ecological pest control. Whenever a large wind farm is built, these ecosystem services vanish and, along with them, so does biological diversity.
… so, in a nutshell, it’s either wind turbines or bats?
Of course we need an energy transition which is in harmony with nature, but this cannot be allowed to lead to any dismantling of ecological standards of protection. On the other hand, protection for one single species cannot always be in opposition to important climate protection measures. Protecting the climate and protecting biodiversity mustn’t be played off against each other.
A real dilemma. What’s the solution?
Current planning regulations are very rigid in the way they are applied. Above certain wind speeds, wind turbines have to be switched off in order to avoid any collisions with bats. Instead of shutting down the whole wind farm, intelligent switch-off algorithms could support the wind farm in such a way that only those turbines would be switched off which are actually a danger for the animals – for example because they are right in the bats’ flight corridors or hunting areas. These technologies are being tested and assessed in a new research project.
How far is your working group involved in that?
At a wind farm in Lower Saxony we are collecting bats killed by turbines. For three months, students are going out in the early hours – before foxes or crows eat the dead animals – to record how high the mortality rate actually is. Also, bat activity at the turbines is being automatically recorded over the entire period so that we will subsequently know where the animals are to be found particularly frequently at the wind farm, and to what extent an intelligent switch-off algorithm can reconcile the requirements of species protection and energy generation even better. There is hardly any data on the subject.
Communicating the results is certainly a key factor in successfully reducing tensions between wind energy and species protection …
Transferring evidence into the public realm is very important – both for concrete planning steps and for defusing heated debates and, instead, having discussions based on facts. A few years ago, for example, we investigated whether monocultures were suitable sites for wind turbines because, it was assumed, they were less diverse and less ecologically valuable than natural deciduous or mixed woodland. We have not been able to confirm this for bat fauna.
Why not?
We have carried out some long-term monitoring of bat activity in a variety of woodland areas in Germany, comparing these areas with respect to biodiversity, bat activity and species composition. The conclusion we came to was that species composition does not depend on the type of woodland, and that forest plantations deemed to be ecologically worthless, such as pine forests, exhibit a high level of diversity of bat species. From an ecological viewpoint, monocultures cannot therefore be justified per se for the expansion of wind energy. We need to have a re-think here.