New tree planting UK
New tree planting in the UK (geograph.org.uk)

The unveiling in January of a government scheme to turn swathes of farmland across Britain into sustainable habitat for wildlife was greeted with cheers among campaigners. The justification for part of the scheme – the planting of trees – is backed by growing evidence of the cooling effects of afforestation. Research conducted at ETH Zurich, reported in November last year, found that areas of some European cities with high tree cover were as much as 12 degrees cooler than those without.

The government’s Local Nature Recovery scheme sounds like a win-win: habitats are restored, land surfaces cool, and farmers are financially rewarded for their efforts. But not all are in agreement. The National Farmers Union in Wales has responded to the scheme with alarm. Already, farms in Wales are being sold to private equity firms who, taking advantage of forestry grants, have bought up land in order to plant trees. Farmers there have warned that any afforestation might do more harm than good if it’s not properly thought through, especially if conifers – known to be damaging to soil fertility – are planted en masse by companies with little understanding of local ecology.

The government has sought to allay another concern. The various projects involved in the scheme won’t go ahead, it has said, unless there is certainty that food production won’t be affected. Any change in the use of agricultural land inevitably risks affecting the productivity of that land. This concern has global echoes. Oxfam warned last year that if too much afforestation or reforestation takes place over the coming three decades, resultant food price rises will worsen hunger. Globally, the organisation estimated, 350 million hectares of land could be forested without causing any significant disruption to food prices. This was the target set in the so-called Bonn Challenge in 2011. But if tree planting were to be the only strategy used for reaching net zero, five times that surface area, equivalent to all the farmland on the planet, would be required.

The risks don’t stop there. If tree planting schemes essentially replicate monoculture practices, the UK’s already alarming rates of biodiversity loss – it now ranks among the least biodiverse countries in the world – could quicken. In 2020 it was reported that 80 percent of commitments made in the Bonn Challenge, which some 40 countries have so far signed up to, were for either monoculture plantations or a limited variety of trees.

Promises to ramp up tree-planting were made by several parties in the last UK elections, indicating that this low-cost – and potentially highly effective – strategy for reaching net zero had broad support. In the US, even Donald Trump backed the Trillion Trees Campaign while in office. But although it might appear an attractive route to tackling the climate crisis, it’s clear there are justifiable fears. In more than a figurative sense then, let’s not miss the wood for the trees.

This piece is a preview from the Witness section of New Humanist spring 2022. Subscribe here.