YouTubers are on a mission to plant 20 million trees. Hundreds of YouTubers are calling on their audiences today to donate money to the nonprofit Arbor Day Foundation, with every dollar raised turning into a tree seedling in the ground. “We want to show that YouTube isn’t just a drama fest, that we actually have real influence and can make real change,” Jimmy Donaldson, who goes by MrBeast on YouTube and started the campaign dubbed #TeamTrees, said in a private video seen by The Verge.

For any big tree-planting scheme, whether those seedlings can live to change the world is a little more complicated. Planting trees can have huge benefits for the ecosystem and the planet, reviving downed forests and helping to fight climate change by capturing the carbon we release when we burn fossil fuels. But to do so, large-scale tree-planting projects need to avoid potential pitfalls.

Nearly half of the world’s trees have been destroyed since the start of human civilization, one study in the journal Nature found. Between 1990 and 2016 alone, humans took down an area of forest larger than the country of South Africa, according to the World Bank. So there’s a lot of work to be done to not only protect remaining forests, but to bring them back to their former glory.

MrBeast set out to plant 20 million trees to commemorate his channel reaching 20 million subscribers. Tree planting projects can be attractive because of how easy it is to quantify how much good you’re doing by simply counting the number of trees you stick in the ground, and one of #TeamTrees’ aims, according to an FAQ for participants, is to take action on climate change. But if that’s the impact it’s going after, the more important tally might be how many of those trees actually live into old age.

“It turns out that many of these seedlings, if you don’t do this well or if people do it who don’t really care about those trees, then they all just die quickly“ says, Eike Lüdeling, department head of horticultural sciences at the University of Bonn. “Sometimes it’s probably a better idea to plant fewer trees and really take care of them.”