For a while I’ve had a persistent noodle in my brain about nature conservation and the question of what we’re trying to conserve “back to”. Reading Isabella Tree’s book Wilding has turned this noodle on its head somewhat and made me even more unsure.
The general scientific consensus for decades has been that post the last ice age, Europe was covered in what they call “closed-canopy forest”, which means the canopy of the trees forms a ceiling and sunlight doesn’t penetrate to the forest floor, and only the highest mountains were without tree cover.
When humans came along, we started clearing trees for settlements, grazing animals and cutting wood (e.g. coppicing) and therefore the theory has been that without any human intervention, nature would take land in Europe back to being forest. In the areas where humans intervened, at least initially, we actually increased the biodiversity because it allowed species that need more light to flourish, such as in meadows or heathland. Various conversation organisations, such as Surrey Wildlife Trust, have grazing herds of cattle in these areas to stop trees from encroaching (called vegetation succession in academic terms) and so maintain those ecosystems and the species that need this habitat. But if pre-humans this land was all forest, then stopping the trees from encroaching isn’t natural. Hence the question of what to conserve back to – if we aim for closed-canopy forests, then we would reduce the biodiversity compared to today in some habitats. But if we aim for healthy, biodiverse ecosystems that aren’t covered all with trees then it’s not “natural”.
However, there’s another view, pioneered by Frans Vera that Isabella Tree references and that the rewilding projects at the Knepp Wildland in West Sussex and Oostvaardersplassen in the Netherlands take as their philosophy. This view thinks of Europe having a landscape like Africa but colder and with different animals. So it would have had predators such as bears, wolves, lynx and herds of herbivores, species now extinct that are like horses, cows and deer. These herds of herbivores would have created an opposing force to the encroachment of trees, resulting in a landscape that is more like grassland than forest and which supports a much broader range of biodiversity.
This theory of closed forest overlooks another force of nature altogether, one that works in opposition to vegetation succession: animal disturbanceFrans Vera
There’s evidence in the fossil and pollen records that support this view – that herbivores were present in Europe longer ago than trees were and that oaks and hazel, which are light loving, have been present in Europe for thousands of years.
There are now 2 sides of this argument – some that are supportive of Vera’s view and others that are vehemently against it and see this as a way of legitimising ongoing grazing on what should be untouched land.
So now I’m less sure about where the we started from, what “natural” means for Europe and consequently what we should be trying to get “back to”. But maybe that doesn’t matter. The landscape has been forever altered by human intervention and we don’t have a time machine to go back and change that. The important thing for me is how we improve biodiversity at the same time as feeding the growing population and that’s the problem we need to solve.