Proponents are arguing for natural regeneration to be taken more seriously in national and international efforts to mitigate the climate and biodiversity crises. In a new publication, the Kew scientists say that, where new trees are needed, the focus should be on letting forests grow naturally, as long as the conditions at the site like soil quality and proximity to existing forests were suitable. ( Read more about why planting trees doesn't always help climate change.) Instead, the trees took over heathlands and grasslands, and lowered the water table, the experts at Kew noted. For example, South Africa spends millions of dollars to clear Australian acacias that became invasive after being introduced to stabilise sand dunes during the 19th and 20th centuries. The wrong trees in the wrong place can cause considerably more damage than benefits, and fail to help people, nature or capture carbon. In January, scientists at Royal Botanic Gardens Kew in the UK warned that tree planting was often being presented as an easy answer to the climate crisis, and a way out for businesses to mitigate their carbon emissions. "Another view is that forest restoration is fundamentally natural, and that humans can assist it, but ultimately it should be governed by natural processes." "There's a perspective that humans did this damage and it's our job to fix it, and that we should govern the process, and just let nature help when it can," she says. But this has largely taken place unintentionally, as people have abandoned farmland to move to more productive areas, or in search of jobs in cities.Ĭhazdon, who has studied natural regeneration for more than 30 years, questions the commonly held assumption that trees need to be actively planted to tackle climate change and biodiversity loss. This is known as assisted natural regeneration.įar from being a new way for tree cover to increase in landscapes around the world, natural forest regeneration has taken place in countries as diverse as Norway, Brazil, Costa Rica, Nepal and Ukraine, according to research published last year by Robin Chazdon, professor emerita in the ecology and evolutionary biology department at the University of Connecticut. Some intervention, such as removing competing plants or grazing animals, may be needed to give natural processes a kickstart. It does not necessarily involve sitting back and letting nature take its course. For this reason, the greatest potential for natural regeneration is in areas next to existing forest, according to the UN's Food and Agricultural Organization. Trees grow from seeds blown in by the wind, carried there by animals or birds, or from plant parts such as stems, leaves or roots. Distinct from active tree-planting, trees are allowed to grow back spontaneously, or with limited human intervention, on land where the original forest cover had been cleared for uses such as agriculture or destroyed by fire. The method described by Tree is known as natural forest regeneration. The pre-Incan technology revived by Peru.The trees' growth was aided by thorny scrub that had also been allowed to grow at the farm, which acts as "nature's barbed wire", protecting the saplings from nibbling deer and the estate's free-roaming cattle and ponies. "Not a single tree was planted, no saplings were bought from commercial nurseries, no tanalised wooden stakes, no polypropylene tubes and plastic ties, no direct financial or carbon costs – no effort," says Isabella Tree, co-owner of Knepp Castle Estate. Birds such as jays can disperse as many as 7,500 acorns in four weeks. Instead, the trees at Knepp Castle Estate in southern England were allowed to spread naturally. But they might be surprised to learn of the secret to this farm's success – none of these trees were "planted" here at all. The transformation is the kind of story that many countries are aiming for with large-scale tree planting programmes, from India to the US to Ethiopia. Twenty years ago, these trees weren't here at all. Alder, hornbeam, ash and birch trees are also thriving. At a former intensive dairy farm in Sussex, England, oak trees now tower up to 20 feet tall (6 metres), sucking in carbon from the atmosphere, providing habitat for birds, mammals and insects, purifying air and water, and protecting land from flooding.