Non-native species must be part of the mix if the UK is to meet its tree-planting targets, says outgoing Forestry Commission head Sir Harry Studholme

Non-native conifer plantations have long been a scourge of conservationists – blamed for wiping out woodland species and disfiguring landscapes. But exotic conifers will be better at tackling the climate emergency than much-cherished broadleaved woodlands, according to the outgoing chairman of the Forestry Commission.

Sir Harry Studholme, who has headed England’s forestry agency for the last seven years, warned that there must not be a repeat of past mistakes in the rush to plant trees to meet the government’s target of net zero carbon emissions by 2050.

New plantations are already causing an outcry with the Woodland Trust last week pledging to remove saplings planted on a wildflower meadow full of orchids in Cumbria.

The placing of sitka spruce plantations on Scottish highlands and across the peat bogs of the Flow Country in the 1970s and 1980s was a “tragedy”, Studholme admitted.

But he said a new generation of woods, increasing Britain’s forest cover to its highest levels since pre-Roman times, must include non-native conifers and other exotic species well suited to a rapidly warming climate.

The Committee on Climate Change has called for a 1.5bn new trees by 2050 – requiring planting on 30,000 hectares of land a year, increasing Britain’s forest cover from 13% to 19%. Charities including Friends of the Earth and the Woodland Trust are campaigning for even more new trees – particularly broadleaved native woodland.

In 2018-19, just 13,400 hectares of new trees were planted – the highest for a decade, and mostly in Scotland.

The government’s target of 30,000 hectares each year by 2025 is “tough but achievable,” according to Studholme “It’s all hands to the pump to deal with climate change.”

It’s not as clear cut as open moorland good, conifer plantation bad Harry Studholme

He predicted it would be “much harder” to reach 1970s levels of more than 40,000 hectares per year. The 1970s tree-planting boom was fuelled by generous tax breaks and by using the cheapest land – which happened to be beautiful upland scenery and ecologically precious peat bogs, which are also a crucial carbon sink.

He said: “We’ve got to be very careful in the rush to plant trees that we think about what we’re planting. A tree is for life, not just the moment you’re planting it. It repays the thinking at the beginning.”

Facebook Twitter Pinterest Pine trees near Braemar in the Highlands. Photograph: Westend61 GmbH/Alamy Stock Photo

While increasing urban tree cover is popular and uncontroversial, Studholme said the main barrier to wider afforestation is high agricultural land prices. Planting on cheap, low-quality agricultural land is contentious because this is usually in upland landscapes valued for wildlife and open moorland. But planting on more expensive, more fertile areas will take land out of food production.

The key to reaching 30,000 hectares a year will be forestry funds via the new system of financial support for farmers after Brexit. This is still being devised by the Department for Environment, Food & Rural Affairs but could fund farmers to shift to some forestry.

Scotland has increased its tree planting largely through private investment but Studholme said that in England the Forestry Commission – if boosted by government funds – could play a key role in planting a new generation of accessible woodlands that provide public recreation, health and biodiversity.

But he warned that conservationists’ hostility towards non-native conifers was “terribly problematic in climate change terms”, with fast-growing conifers able to sequester more carbon than native deciduous trees.

The denser timber of native oak sequesters more carbon per cubic metre. But there are many more cubic metres of timber in a Douglas fir plantation because the trees can grow much closer together, and the firs grow more quickly.

According to Studholme, while new woodlands should not be planted on peat soils – already a valuable carbon sink – non-native plantations could enhance some open moorland. On Dartmoor, for instance, conifer plantations support birds including goshawks, siskins and crossbills that are not found in open landscapes.

“It’s not as clear cut as open moorland good, conifer plantation bad,” he said. “Are you better having bracken or sitka spruce? In terms of employing people, carbon absorption or biodiversity, sitka spruce is not as bad as it seems.”

He said there was not one “magic” single species but that we needed resilient mixed species plantations in an era of rapidly changing climate and new tree diseases.

“Our experience in the Forestry Commission over 100 years is that if you have a prescriptive answer it’s just wrong,” he said. “Land changes, the soil changes, the climate changes. We need to do what’s right for each different bit of land. To narrow your palette to only native species in forestry is a really restrictive idea.”

After seven years as chairman, Studholme is retiring to spend more time managing his forest in Devon. He has plantations of oak, Douglas fir, western red cedar and larch, and is experimenting with disease-resistant elm cultivars as well as trialling walnut species, which could provide a new crop as Britain’s climate warms.

He said both deer and grey squirrels would need to be controlled if we want healthy new trees.

“It’s an uncomfortable thing to say, it’s complicated, but we’re living in a managed landscape and it has been for centuries,” he said.

If the public want to stop using polluting single-use plastic tree guards, “the answer to not having guards is very, very good deer control”, he said.