Europe is the second-most densely populated area in the world, surpassed only by Asia. This fact has created a great demand for land, both to house the population and to be used for agriculture to support the nutritional needs of those living there. On top of that comes the need for land to support industry, which is also not insignificant.
This leaves very little space for untouched nature, which is completely wild and without any human influences. Landscapes, particularly in the past, were often changed without regard for how that influenced the ecosystem as a whole. Species that were considered unwanted were driven out and sometimes even driven to extinction in some areas. A prime example of this is wolves.
However, now many governments are realising that some of these changes were too far-reaching. Many rivers that were straightened or otherwise changed are being returned to a more natural flow, allowing different species of fish and insects to thrive. In other places, otters and beavers are being released into areas where they were previously driven out, to help re-establish a more natural ecosystem. This kind of process is called rewilding. Quite often, changing even a little thing can create huge differences in the whole system because it acts as the catalyst for a whole chain of effects down the line.
One such example where the effects have been studied extensively is the rewilding efforts undertaken in Yellowstone, a well-known national park in the United States.
Here wolves were reintroduced to the park, which is an unusual move and one that would be impossible in many places due to population density and the risk to livestock. But with the size of Yellowstone, this was a place where the reintroduction of the top predator was possible. And because of the presence of the wolves, the ecosystem began to change; larger mammals such as deer and elk began being more cautious as they now had a natural enemy and indeed they began to dwindle in numbers, leaving more food for smaller animals such as beavers, foxes, and badgers which began to return. It was also good for willow trees that had previously been suffering from the large amounts of deer and elk feeding on them but flourished after the wolves returned. The same was true for other trees and vegetation, which in turn stabilized the riverbanks because there was less erosion now that there were more plants. Because of the return of smaller prey, foxes and birds of prey also began to be more prolific and in general, the biodiversity rose dramatically over a relatively short amount of time; some changes came almost immediately while others took about twenty years to manifest.
Because of this, it has been theorized that top predators are one of the major factors in determining the health of an Ecosystem because their presence or lack thereof has such a huge impact on several other species that themselves impact other parts of the system. It is therefore theorized that we need to begin at the top of the food chain, not the bottom, to see changes, though this is contested as well, and needs further research.
What is certain is that rewilding is a topic that interests many governments the world over and that it is something we will likely see more of in years to come.
Read more:
https://www.worldatlas.com/articles/european-countries-by-population-density.html
https://www.theguardian.com/environment/2020/jan/25/yellowstone-wolf-project-25th-anniversary