The United Nations designated 2021 to 2030 the Decade on Ecosystem Restoration to prevent, halt and reverse the degradation of ecosystems on every continent and in every ocean. To that end, the European Union and 26 nations, along with donor support, recently pledged $16 billion to protect, restore and sustainably manage forests. A significant portion of the monies will be spent on reforestation.

Many reforestation projects focus on the number of trees planted, with less attention to how well they survive, how diverse the resulting forests are or how much carbon they store. A study of data from 176 reforestation sites found that on average only 44 percent of newly planted trees last more than five years, with some sites reporting a sapling survival rate of less than 20 percent. 

Several studies have explored ways to improve survival rates. Promising measures include planting near mature trees, fencing out cattle, improving soil conditions, planting native species first to pave the way for other tree species and involving local people to support reforestation efforts.