In simple terms, the author puts forward his case for the 'rewilding' of large tracts of Britain. Most of upland Britain is, in his words, 'sheep wrecked' - over grazed. This results in a barren landscape where the naturally occurring plants are reduced to a mere handful of species. The survivors are the few that are unpalatable to sheep, with only the very steepest slopes safe ground for vegetation to take any hold. Needless to say, such a habitat breakdown has a knock-on effect across all wildlife, affecting species numbers and composition.
I have witnessed the destruction caused by sheep and deer at Ben Lawers in Scotland. By the visitor centre there is a burn that comes down from the hillside, meandering through a shallow depression. This has been fenced off to allow the vegetation to regenerate. You are allowed to wander through this area and the species diversity and lushness is so much grander than the impoverished grazed area outside of the fencing.
Monbiot argues that the eradication of the top predators (the keystone species) is what ultimately brings down the environmental deck of cards. The loss of the wolf, for example has lead to a surge in deer numbers, which now overgraze the woods and, with no predators, wander far away from their natural woodland habitats, unchecked. Mammals such as wolves, boars and beavers carried out essential functions within the natural world which allowed diversity and healthy habitats to flourish. They kept the population levels of their prey down, they opened up undergrowth, they kept river water clean and running properly.
His depiction of what we have lost (mainly in northern Europe but also across the world) is mind-blowing, particularly his account of the teeming sea life that was once found around our coasts. I had no idea that the death-knell had started to be sounded so long ago - it is not just a recent phenomenon. The demise of the megafauna may have been helped along by climate, but man had more than a helping hand in the process.
This is a thought provoking book. Reserves are, he claims, maintained in a fashion that try to keep alive a man-made 'ideal'. Most of our reserves are, in fact, guarding non-natural habitats. We strive to maintain (or get back to) population levels that were present at the beginning of the 20th century. The error in our ways is that these levels were already greatly suppressed. The author is not just spouting out his vision of an ideal world - he tackles the financial costs, the cultural effects and the realistic hopes of what might be achieved. Some of our European neighbours are already giving rewilding a go, and it is working. The biggest problem for such projects to get off of the ground here is getting the public to be at ease with creatures such as the wolf and lynx making a return.