Farmers in Niger regrew 200 million trees, and nobody planted them

The standard way to talk about restoring a degraded landscape is to count seedlings. Pledges are announced in trees planted: a million, a billion. Photographs are taken of people with spades.

What happened in southern Niger involved almost none of that.

Farmers stopped clearing the stumps that were already in their fields, protected the shoots that came up from them, and pruned the results. Over roughly thirty-five years, that produced an estimated 200 million trees across at least 12 million acres, according to National Geographic's account of the research — and the researchers regard 200 million as a low estimate, with the area possibly nearer 15 million acres.

Nobody planted them. They were already there, underground.

Why the roots were still alive

This is the part that makes the whole thing work.

When land in the Sahel was cleared for farming, the visible trees went — but the root systems below did not die. They stayed alive, sending up shoots that were then cleared again each season as weeds, year after year.

The technique now called farmer-managed natural regeneration consists mostly of stopping. Choose the shoots worth keeping, protect them from grazing and from the next clearing, prune them so they grow into trees rather than bushes, and keep farming around them.

It costs a fraction of planting. And the survival rate is not comparable — a seedling from a nursery is a small plant with a shallow root system dropped into hostile ground, while a shoot from an established root system already has a decade of infrastructure beneath it.

How it was discovered

Not by the organisation that funded it, because there wasn't really one at the centre.

Gray Tappan, a geographer with the US Geological Survey, and Chris Reij, a Dutch forest scientist, began documenting it in 2004. They compared aerial photographs from 1957 and 1975 against satellite imagery and went to look on the ground.

The comparison showed something nobody had announced: across Maradi, Tahoua, Zinder and the area around Dan Saga, the tree cover in farmland had increased, substantially, over decades — in the middle of a region that global coverage describes almost exclusively in terms of desertification.

The change had been under way since the early 1980s. It took two decades for anyone outside to notice, because a landscape slowly regaining trees does not generate news.

What the trees did

200m

trees regrown across southern Niger, treated by researchers as a low estimate

500,000t

extra cereal a year produced in tree-rich regions of southern Niger

2.5m

additional people that extra cereal could feed

Trees in a field are not decoration. They break the wind that strips topsoil and sandblasts seedlings, drop leaf litter that feeds the soil, and in the case of nitrogen-fixing species such as Faidherbia albida, fertilise the crop directly. One farmer told National Geographic his millet harvest went up fivefold.

There is a second effect that rarely makes the summary. Firewood came back within walking distance, and the hours women had spent collecting it were freed — in the accounts collected, going into producing medicines, oils and soap for income.

The honest limits

This is not a formula that can be pasted onto any degraded landscape, and the research says so.

A study in Scientific Reports in September 2020, led by Madelon Lohbeck, examined 316 plots in agroforestry parklands in Ghana and Burkina Faso and found what constrains regeneration. Grazing pressure and farming intensity suppress it. Crucially, there must be trees of the desired species nearby — regeneration cannot produce what has no seed source or surviving root stock. Where those preconditions fail, the paper concludes, natural regeneration has to be supplemented with actual planting.

That same paper puts Niger's revegetated area at more than 3 million hectares since the 1980s — a lower figure than the 12 million acres cited above, from a different method and a different year. We give both rather than picking the more impressive one.