George Monbiot’s recent work on ‘rewilding’ has brought attention back to the degraded state of many of Britain’s uplands. Low productivity sheep pastures reduce biodiversity and increase the rate of storm runoff into rivers. Take sheep away and most uplands would quickly revert to woodland, supporting the large carnivores that he so fervently wants back in the UK. Although the UK is slowly gaining forests, it is still probably the least wooded country in Europe. Monbiot’s rewilding would also approximately double the UK’s capacity to produce wood for energy use. Today’s woodlands can produce enough fuel for about 1 million homes and rebuilding forests on upland pasture might increase this to over 2 million households. It would also increase employment in some of the least wealthy parts of the UK and make energy supply slightly more resilient. It would also reduce carbon emissions.

Two weeks ago, an attentive audience listened to talks on the bright future for British wood fuels. In a Surrey hotel that was once home to John Evelyn, a man with some claim to be Britain’s first professional forester, speakers examined how the country’s woods could be brought back into productive use. Actually, the location was doubly appropriate; Surrey is the most wooded county in England. The timing was also right. The Renewable Heat Incentive (RHI) for domestic homes, a government scheme that has taken almost as long as an oak to come to maturity, will produce a profitable market for wood pellets next year and this has stirred woodland owners and biomass stove installers into long-overdue action.

Today, over 50% of Britain’s woodlands are completely unmanaged. Despite what some environmentalists might say, this is not good for local ecologies. Unmanaged woodland becomes overcrowded, reducing the light on the floor of the forest and reducing the number of plants, birds and animals able to prosper. Careful silviculture will give us abundant wood energy and improve biodiversity as well as reducing the risk of flooding.

Matthew Woodcock from the Forestry Commission looked at the amount of wood that the south east of England would feasibly produce for energy needs. (Suspicious readers may think I have made up the lecturer’s name: a woodcock is a bird that spends much of its time in forests and its numbers have been falling as British unmanaged woods have become more overcrowded.) Matthew looked at the current level of forest cover in the south east, and offered an estimate of how much spare and low value wood could be annually harvested for energy in the region. He came up with a figure of about 1 million cubic metres, approximately enough to make the wood pellets necessary to heat 100,000 homes, slightly more than one per cent of homes in the area.

Extrapolated across the UK, the amount of woodland not currently managed for fuel or other forest products is about ten times the amount in the south east. The total amount of extra energy that is potentially available is probably about 15 terawatt hours, or approximately enough to heat one million of the 26 million homes in the UK. So, as is often said, locally produced wood cannot be a central part of the UK’s decarbonisation plans. However, its impact on local economies can be substantial. One relatively small wood products plant in Kent, Torry Hill Chestnut Products, supports 30 jobs processing 800 hectares of sweet chestnut, a rate that at least matches conventional arable farming.

Today, we were told, the UK is a net exporter of wood pellets for domestic boilers. (The conversion of Drax power station partly to wood means that the UK is nevertheless a substantial net importer of fuel from forests). The RHI will soon offer a subsidy about 12p a kilowatt hour for households to switch to pellet stoves. Given that pellets are currently selling for about 5p a kilowatt hour, the finances of switching from oil or LPG to wood are almost ridiculously favourable once the RHI comes into force in the middle of next year.

Mark Lebus of LC Energy followed up the Forestry Commission talk, looking at the scope for industrial and commercial users to switch to wood-derived heat. LC Energy supplies Heathrow, Center Parcs and Waitrose with its wood. He was equally confident about the future of wood chips and pellets in the south east, showing how his firm could source enough material within 30 miles of any of its customers.

Nevertheless, the resources of timber are necessarily limited, given the relatively small extent of mature woodlands in the UK. And this is where Monbiot’s point comes in. Uplands used for sheep grazing are by far the easiest way of substantially extending our forest cover. We shouldn’t be looking to replicate the old Forestry Commission’s vast plantations of single species. But we can let nature back onto the uplands, gradually coaxing life back into the hills that were once almost entirely forested. Of course the farming community will complain – you might have been surprised at the vehemence of some of the newspaper comments about George’s conclusions about rewilding in mid-Wales newspapers this summer – but the future of the 2 million or so hectares of upland that is currently grazed by sheep is not growing meat. There are more jobs, more tourism, more nature in properly managed, diverse forests than there can be in livestock farming.

After a generation, when upland woods will be growing fastest, the net amount of carbon extracted from the air will be equivalent to about 1 percent of UK greenhouse gas emissions. Not a huge percentage, but in combination with the other advantages that Monbiot has so persuasively identified, a worthwhile improvement to Britain’s environment.