Tea time. Used under Creative Commons License. Flickr/Kate Russell

The more one hears about the essential role of trees in the weather (atmospheric rivers!), in soils (the wood wide web!), and in biodiversity (tropical rainforests!), let alone carbon sequestration, the more one understands the importance of forests comprised of mixes of different species of trees of different ages.

Large, single crop plantations of one or two tree species are inherently fragile: just look at the massive dieback of plantation conifers underway in North America and Europe. Whether they finally perish through drought, infestation or wildfire, their carbon goes back to the atmosphere and their soils erode rapidly, exacerbating destructive floods.

By contrast, natural forests have hundreds of different species of trees ranging in age from saplings to millenarian giants, and literally millions of other species making a living in the whole biome, from deep in the soil to the air above the canopy. With such complexity, pests don’t stand a chance to do real damage, fire struggles to kill it all off, and many species will survive the increasingly extreme weather the climate crisis is throwing at forests.

What that means is that very often, the easiest, cheapest and fastest way of getting a thriving forest is rewilding – a fancy word for sipping a nice cup of tea and relaxing in an easy chair while letting nature do its job.

The speed with which degraded forestlands can regenerate is astounding. Almost unnoticed, an immense amount of forest rewilding is already underway on all five continents. Europe has more trees on it today that it has had in many centuries, and much of that is natural forest invading abandoned agricultural lands. In an age when we tend to focus all too much about the deforestation of iconic places like the Amazon, that is heart-warming news.

And even there, the news is not all bad: recent research suggests that over 70 percent of the Amazon’s deforestation happens on land that had already been deforested before, in an industrial sort of pasture fallowing — cut the forest, grow grass, graze cattle, abandon land after two years as the soil is exhausted, let forest regenerate, come back a few years later, and repeat. Some patches are now being deforested for the fifth time.

But if our forests need to move away from plantations towards mixed stands, ideally regenerating on their own, the foresters amongst you may well ask: where is all the timber and fiber the world needs going to come from? And there, too, the answer is unorthodox: from farmlands, through agroforestry.

In Europe alone, we find that we can add tens of billions of trees to farming landscapes. Those trees provide ecosystem services such as additional fertility and water cycle buffering to the crops they share the field with, boost the income of their farmers, and add resilience to droughts, storms and pests. Indeed, it is often because of these resilience services that farmers first switch to agroforestry. As the climate becomes increasingly extreme, that is an increasingly convincing reason to plant them. Just ask the smallholders of the Sahel, in Niger, Mali or Senegal, where millions of hectares of new agroforestry parklands have grown in the past decades.

But if rewilding and agroforestry are the way to go, how do we get there? Often, forest protection and rewilding is only possible “under very specific conditions,” as a report from Madagascar makes clear. “The local community must be able to trust that the government won’t let some commercial interest or a political heavyweight slip through loopholes to exploit a forest that its everyday neighbors can’t touch. And local people must be able to meet their own needs too, including the spiritual ones.”

That suggests that governance is capital.

And the same applies to agroforestry. In the Sahel, the trees came back once the farmers were assured to have the tenure of them (no official could fine them for cutting off a few twigs for the kitchen fire). In Europe, by contrast, agroforestry struggles to become established: farmers are afraid of planting trees because they might lose their agricultural subsidies.

We would be hard put to imagine places as different from each other through climate, wealth and culture as Europe, Niger and Madagascar. Yet in all three places, it is laws, regulations, rules and practices –governance — that dictates if the trees will come back — or not.

The challenge of the age, the way to get a trillion trees back into the landscape, is thus largely not a challenge of planting. It’s a challenge for lawyers and governments, for communities and cooperatives, to craft the governance models that will encourage people to welcome trees back into their lives.