Don’t meddle: let nature restore itself on its own. Old forest will spread over nearby farmland. It’s cheap, and often best.

LONDON, 22 June, 2021 − British scientists have just confirmed something that might have seemed obvious: to regenerate the natural world, the best way is often to let nature restore itself on its own.

That is: left to its own devices, and with help only from wild birds and mammals, bare agricultural land turned into dense native woodland in little more than half a human lifetime.

Nobody needed to plant trees and shield them with plastic tubing; nobody had to patrol the protected zone or fence it against rabbits and deer, or attempt to choose the ideal species for the terrain. It all happened anyway, with the help of the wind, the wild things and a species of crow called a jay.

The research offers lessons for governments that have committed to restoring natural forest as part of the arsenal against global heating and climate change: it need not cost much.

Fast work

“Biodiversity-rich woodland that is resilient to drought and reduces disease risk can be created without any input from us,” said Richard Broughton, of the UK’s Centre for Ecology and Hydrology.

“Our study provides essential evidence that passive rewilding has the potential to expand native woodland habitat at no cost and within relatively short timescales.”

He and his colleagues tell the story in the Public Library of Science journal PLOS One. They simply monitored the progress of two farmland fields over two periods of 24 and 59 years respectively: one had been abandoned in 1996, the other in 1961. Significantly, both fields − of 2.1 hectares and 3.9 hectares, and labelled New Wilderness and Old Wilderness − were close by a patch of ancient woodland.

This was the Monks Wood national nature reserve in Cambridgeshire, a tract of wildwood in eastern England that has been studied in fine detail for many decades and documented since 1279 AD.

“Passive rewilding has the potential to expand native woodland habitat at no cost and within relatively short timescales”

Of the two abandoned neighbouring fields, one had been grazing land, the other laid down to barley. Brambles and thornbushes colonised the neglected fields, to provide cover for seeds, nuts and acorns spread by wild mammals and birds.

After 23 years, 86% of the grassland had turned into shrub and sapling that had reached an average height of 2.9 metres, with a density of 132 trees per hectare: 57% of these were the oak Quercus robur. The Old Wilderness, after 53 years, had 100% cover averaging 13.1 metres in height, with a density of 390 trees per hectare, 52% of them oak.

Climate scientists have been urging the protection and restoration of natural ecosystems for four decades. Conservation scientists, alarmed at the potential rapid rise in rates of species extinction along with the damage to natural habitats, have been urging the same thing for even longer.

Both have made a case for restoring the wilderness: the debate has been about the best ways to make this happen. More trees should mean more carbon absorbed from the atmosphere. But more climate change might make such restoration, through for instance deliberate plantation, increasingly problematic.

Reheating the Arctic

So the next question is: could Nature restore itself? Rewilding is still at the experimental stage: a process backed by in some cases deliberate re-introductions, for instance of beavers and other wild species in Europe. There is even an argument that in the fastest-warming zone of the planet, the Arctic, the reintroduction of large herbivores could help slow climate change and contain global heating driven by ever-higher ratios of atmospheric greenhouse gases.

The clear message of the latest study is that − at least if natural forest rich in wild birds and mammals is close by − then nature can be left to do what nature does best. There were no costs of planting, there was no risk of disease introduction from nursery-grown saplings, and no need for plastic tubes to protect the tender young tree trunks from predators.

Blackthorn and hawthorn helped screen the young trees from hares, rabbits and deer. Seeds were dispersed by helpful wild agents, among them squirrels and wood mice and a bird commonly regarded as a pest, the jay, Garrulus glandarius.

“The huge benefits that jays provide in natural colonisation by dispersing tree seeds, especially acorns, help create more woodland habitat for all wildlife and far outweigh any impact of predation,” Dr Broughton said. − Climate News Network