You might think that a book about a farm in West Sussex could not be capable of exploring ideas of truly global importance. Equally, you might think that a book that does advance such lofty ideas could not be sufficiently anchored in hard-won experience. On both counts, you'd be wrong. Wilding: The return of nature to a British farm does both with detail, authority and passion.
The author, Isabella Tree, is married to Charlie Burrell whose family have owned the 3,500 acre Knepp Estate north of Worthing for over two centuries. The estate was farmed intensively since the Second World War, in parallel with so much of Britain's farmland, but it rarely made a profit. The decision to defy convention and re-wild the estate has had a transformative effect - on the land, on its biodiversity and on our understanding of ecosystem recovery.
Local opposition was initially severe. The land started to look unkempt and this drew criticism from many quarters. But gradually - with patience, courage and tenacity - this has fallen away as appreciation of what is actually happening has become better understood.
Isabella Tree's wonderful book describes this process with great honesty - and this makes for an inspiring read. She guides the reader through the gradual recovery of the estate as objectively measured by an endless procession of subject specialists, each making a kind of pilgrimage to see the changes gradually happen. Oaks began to flourish once cropping and cutting stopped. Ponies, pigs and longhorn cattle were introduced. The owners held back, documenting everything. Purple emperors, scarce and elusive, moved in, feeding on nectar not flowers. Eighty-four were counted in five hours one July. Nightingales and turtle doves are now regular summer residents, the latter back from near extinction.
The author logs these recoveries in detail, emphasising the role each plays in the broader interplay of ecosystems. What seems to be happening at Knepp is that the whole is greater than the sum of these individual parts. It is as if by seeing that unexpected recoveries can be enabled by stepping back we uncover proof that collateral damage originally occurs when we intervene (by, for example, using neonicotinoids and organophosphates) in the first place.
These re-wildings were accompanied by something even more startling: that the diminishing soil fertility caused by constant ploughing can be stopped and then reversed by selling the plough, by refusing to use chemicals and by leaving nature to repair itself. The debasement of soil into dirt and the collapsing of the nutritional value of fruit and vegetables can be reversed. Stepping back and letting dung beetles, worms and the invisible processes of the soil go to work returned goodness to the soil and re-enabled the carbon sequestration process. One team of soil scientists has espoused the view that "if the content of organic matter in the world’s farmed soils was increased by as little as 1.6%, the problem of climate change would be solved". Not many ideas are as grand - or as pressing - as that.
I was shaken awake by Edward O. Wilson's observation, when I first encountered it, that "in a pinch of garden soil, about a gram in weight, live millions of bacteria, representing several thousand species. Most of them are unknown to science." Isabella Tree has added to that by saying that a single handful of soil contains "more organisms than the total number of human beings who have ever lived on earth". In acting local, as the saying has it, Knepp should be helping us to think global.