Ravaged by farming and logging, Brazil’s Atlantic Forest stands at only 25 percent of its original extent — once a quarter of the size of the Amazon .

Over the past two decades, however, the forest has slowly started to return — with nearly 3 million hectares (7.4 million acres) of its area restored .

How did Brazil accomplish this — and how could other countries follow suit?

The answer may surprise you, explained Conservation International restoration expert Nikola Alexandre in a recent article for news outlet Al Jazeera : Brazil didn’t spend billions to plant trees or employ cutting-edge technologies.

Instead, they left the forest alone.

The process of allowing trees to grow without disturbance by human activity is known as “assisted natural regeneration.” As Alexandre pointed out in the article, it’s one of the most cost-effective — and just plain effective — ways to restore forests to the planet’s degraded lands and “help nature run its course.”

“The premise of assisted natural regeneration is that…