It’s easy to understand why people want to plant trees.

Ambitious reforestation efforts — now aimed at planting or conserving a trillion trees — have captured public attention, and with good reason: Earth’s forests are absolutely vital to staving off a climate crisis and protecting nature.

But what about grasslands?

Stretching across 40 percent of the planet, grasslands hold more than a third of the world’s land-based carbon in their vast underground root and soil systems. They are bastions of biodiversity and contribute to the livelihoods of 1 billion people worldwide. In some cases, grasslands are disappearing faster than forests — yet they are overlooked and undervalued .

“Ironically, some grasslands are being threatened by inappropriate climate actions, like planting trees where they don't belong,” said Conservation International scientist Heidi-Jayne Hawkins. “That’s a problem for all grassy ecosystems — whether it’s Brazil’s Cerrado, or India’s grasslands or South Africa’s savannas.…