Source: The Conversation – UK
Wildfires that have swept across Britain’s upland moors and lowland heaths in unprecedented tinder-dry conditions have left behind expanses of smoking, blackened vegetation.
Once the smoke has cleared, what is recovery going to look like? How long before the first green shoots of recovery will emerge?
Remarkably, the answer to the latter question may be “days” rather than weeks, months or decades. That’s because both heaths and moors contain several distinct habitats, each of which responds differently to fire.
Dry lowland heaths are dominated by heather, a dwarf shrub that produces much fine woody tissue – excellent fuel for fires. Fire can readily consume these plants, but the heat can also stimulate germination of seeds buried just below the surface, protected from the worst of the flames. Seedlings may then emerge within months, while younger heather plants that survive the fire tend to branch vigorously afterwards. A recognisable heather canopy can therefore re-establish within a few years.
Wet heath behaves differently. Hare’s-tail cotton grass and purple moor grass form dense fire-resistant tussocks from which new shoots will emerge within days, while common cotton grass can also regenerate rapidly from its protected root systems.
This means a landscape can look dead almost immediately after a fire but begin producing fresh green growth surprisingly quickly. Yet, that isn’t the same as a true ecological recovery.
Some important plants in wet heath and peatland are far more vulnerable. Cross-leaved heath, for example, is a more delicate form of heather, and its recovery depends partly on whether its roots remain protected by waterlogging as the fire passes above. Sphagnum, or bog moss, can survive surprisingly intense heat because its waterlogged tissues beneath the surface remain protected. Even if its surface layer is scorched or burnt away, the living parts beneath can survive and produce fresh growing tips, albeit slowly.
Where fire penetrates deeply into dry peat, however, the consequences are much more severe. Peat can smoulder for days or even weeks, killing the deep roots of plants and the underground seed store. The result can be a hostile expanse of bare peat that even heather and cotton grasses may struggle to recolonise for a decade or more.
How Britain’s moors became flammable
Traditionally, dry sandy expanses of heathland were maintained in their open heather-rich form through intensive grazing by cattle and sheep and, since early medieval times, by rabbits. In even earlier times, large beasts such as bison would have helped create patches of open heath within natural woodland. Meanwhile, beavers would have helped maintain wetland areas, creating effective barriers to fire.
Upland moorlands are more complex, partly because of their past and present management. In their truly natural state, these landscapes would have contained much more wet bog and moss-rich temperate rainforest. The landscape would have slowed the movement of water to reduce flooding downstream, and would have been naturally resistant, though not immune, to wildfire.
Much of this natural mosaic has been lost. Over the past 250 years or so, wet upland bogs have been converted into drier, heather-rich heaths and moors through repeated drainage and managed burning. The result is an abundance of flammable dry biomass that can help wildfires spread.
As with lowland heaths, the plants that dominate these altered landscapes – heather, cotton grass and purple moor grass – can recover rapidly from fire, either from seed or from dense fire-proof clumps known as tussocks. Familiar vegetation may therefore return within five to ten years.
But many of the plants that make a healthy peat bog function as a diverse ecosystem are much more sensitive to fire and can take far longer to return. Their recovery depends on restoring the conditions that allowed them to thrive in the first place.
This is why peatland restoration matters. Natural recovery from severe degradation can take many decades, but active restoration can short-circuit the process. Blocking drains and restoring Sphagnum can return peatlands to wetter bog habitat, helping to re-establish within a decade the plants that will eventually form peat.
Restoration of temperate rainforest on the drier slopes will take longer, but is already happening with government support. Within a lifetime, the face of Britain’s uplands may start to be visibly transformed into a more climate-resilient mosaic of wetland and woodland.
Richard Lindsay is Senior Research Advisor to the IUCN UK Peatland Programme and Head of Environmental & Conservation Research in the Sustainability Research Institute, University of East London. In the latter role he has been Co-Investigator on projects funded by UKRI, and receives funding on a consultancy basis from the IUCN UK Peatland Programme. He is a member of the Green Party, Plantlife, RSPB and Greenpeace.