Over the last three decades, our planet has lost about a billion acres of forest. The response among policymakers has been sluggish at best, often amounting to little more than lip service, but a growing recognition of the ramifications of forest loss on this scale has led to tentative signs of more substantive action over recent years. At 2021’s COP26 climate summit, more than 100 world leaders pledged to end deforestation by 2030, and ambitious tree-planting programs have been set in motion around the globe. Among politicians of all stripes, it seems, trees have never been so popular.
Done carefully, tree-planting is an important line of defense against climate change. But there’s another that could be just as valuable, if not more so – especially in the short term: simply leaving our existing forests alone to function as nature intended.
Evidence suggests that allowing forests to regenerate of their own accord – a process known as “proforestation” – is a more effective, and perhaps more importantly, more immediate way of sequestering carbon from the atmosphere than planting new forests. Coined by scientists William Moomaw and Susan Masino, the term basically means, in Moomaw’s words, “allow[ing] trees that are already planted, that are already growing, to continue growing to reach their full ecological potential, to store carbon, and develop a forest that has its full complement of environmental services.”
Older trees sequester significantly more carbon than young ones (according to one study, around half of all carbon stored in older natural forests is stored in the largest 1% of trees). Harvesting young trees – the fate that awaits many of the saplings being planted today in commercial plantations – means those trees will never have the chance to develop into older trees (yep – not rocket science), and therefore that they will never reach their full carbon sequestration potential. And those young trees that are allowed to develop will only begin to capture significant amounts of carbon many years down the line.
One study of forestland in the northeastern U.S. found that older, natural forests retain more than double the amount captured in regularly-harvested ones. Other research has concluded that replacing natural woodland with young forests in fact creates a net increase in carbon emissions. It’s “no management” scenarios that bring the greatest carbon storage capability.
But what does it mean to say we should encourage proforestation, if not just by ending deforestation? Obviously, the destruction of old growth forests has to stop (a good place to start is with the forest products industry – recent moves by Proctor & Gamble, for example, have shown that shareholder advocacy can have a real impact). Restoration programs should focus on restoring degraded land to natural forests and making sure those forests are protected. Likewise – again, not rocket science – protections are needed to ensure that existing older and “middle-aged” forests remain intact, allowing the latter to reach their full potential and the former to keep up the good work they’re already doing.
Aside from investing in nature-based climate strategies in general (right now, less than 3% of climate funding goes to nature-based solutions), getting the most out of natural forest regeneration efforts requires us to know where to focus those efforts. Biden’s Earth Day 2022 executive order, instructing the Department of the Interior and Department of Agriculture to inventory mature and old-growth forests so as to draw up appropriate policies for managing and preserving them, is a step forward in this regard. Large-scale mapping projects on an international level have similarly sought to identify the forest areas with the greatest potential to combat climate change if simply left alone. Investment in these kinds of studies, and their use as a basis for appropriate shifts in land use policy, will be crucial.
In short, we need to get our priorities right – and this applies as much to support for international efforts as it does to domestic ones, firstly since research indicates that the places where forests are most effective in terms of carbon capture are in tropical and subtropical regions of the world, and secondly because of the questionable efficacy of many existing reforestation commitments. Currently, around two thirds of all such commitments under the Bonn Challenge and other forest-related climate mitigation schemes involve either agroforestry or planting monoculture plantations as for-profit enterprises – both of which, at best, lag way behind natural forest regeneration in terms of carbon capture potential and the other benefits natural forests bring (increased biodiversity and so on), and at worst, can create more problems than they solve.
Critics of tree-planting as a means of carbon capture often tend to implicitly portray the question of reforestation vs. natural regeneration as an either-or scenario. It isn’t. Tree-planting is one thing we can do. It has its positives and negatives. Allowing forests to regenerate on their own is another – and doing so can effectively complement properly thought-out tree-planting programs and other forest-based solutions. “It’s not that we shouldn’t do afforestation [planting new trees] and we shouldn’t do reforestation,” said William Moomaw in a 2019 e360 interview on the subject. “We should. But recognize that their contribution will be farther in the future, which is important. But in order to meet our climate goals, we have to have greater sequestration by natural systems now.”