A child hoisted a Tunisian flag up a pole beside a palm tree in the concrete courtyard of her school in Tunis. The national anthem blared and gardening gloves were handed out to the watching crowd of environmentalists, local politicians and call-centre employees, who were on a corporate responsibility outing and wearing matching T-shirts printed for the occasion. The Eid el Shajra (‘tree festival’) has taken place annually on the second Sunday in November since 1958. Tunisia’s first president, Habib Bourguiba, said he wanted to ‘awaken in the nation a lively interest for trees, an appreciation for their aesthetic and economic value’.

Under Zine El Abidine Ben Ali, however, the festival would fall around the 7 November anniversary of the coup that brought the dictator to power, and the trees were dedicated to cleaning his image rather than the air. ‘There would be TV interviews and a big gathering of people around the president as he plants just one tree,’ Essia Guezzi, a 32-year-old environmentalist, told me.

As the climate crisis accelerates, tree-planting campaigns with targets in the billions have proliferated around the globe, backed by states, corporations and environmentally conscious citizens. The Labour Party announced today that it would plant two billion trees in the UK by 2040, in addition to its proposed windfall tax on oil and gas companies.

Shaul Cohen is the author of Planting Nature: Trees and the Manipulation of Environmental Stewardship in America. ‘Trees are mostly inherently good,’ he says, ‘but there is an idea that whoever plants the most trees is the best steward and this is used by the timber business and government to generate confidence that their environmental practices are sound when that is not the case … They might not be the right kind [of tree, or] in the right place at the right time.’

The Arbor Day tradition in the United States was started in Nebraska in 1872 by the journalist Julius Sterling Morton, who was worried that the arid, treeless landscape would not be attractive to European settlers. The League for Reforestation was set up in Algeria in 1882. Most of its members were French farmers and property owners, who promoted environmentalism as a way to exert control over the land. A commission had been established in the 1860s to look into the problem of forest fires; its members were businessmen with concessions to exploit Algeria’s cork forests. ‘The Arab,’ they wrote, ‘is the personal enemy of trees.’

In Planted Flags, Irus Braverman cites a study showing that, of the 418 Palestinian villages depopulated during the 1948 war with Israel, almost half are now situated in nature sites, of which 86 are state forests. ‘It is sometimes hard to say where nature stops and politics begins,’ Braverman says. ‘These are national imaginaries and there is a struggle over them through the landscape. There is an assumption that trees are always good, and that is what I try to challenge when I demonstrate the devastating ecological and human impacts they can have.’

In July, when the Ethiopian government claimed to have broken a world record by planting more than 350 million trees in one day, critics of the prime minister, Abiy Ahmed, said it was a stunt to divert attention from political tensions.

Trees can also work as internal, and ultimately depoliticising, propaganda. We feel powerless in the face of the climate crisis, and planting a tree – or paying someone else to plant a tree – can make us feel like we’re doing something. But planting trees doesn’t offset the urgent need to reduce fossil fuel consumption.

The Canadian prime minister, Justin Trudeau, pledged in September to plant two billion trees over the next ten years. But he also approved the Trans Mountain crude oil pipeline, in spite of opposition from indigenous and environmental groups. And Canadian mining firms continue to operate in Brazil, where more than 9700 square kilometres of rainforest (close to a billion trees) were cleared in the year to July, an increase of 30 per cent on the previous year and the highest since 2007-8.