We’ve long known that diverse stands of trees tend to be more productive than monocultures. What we haven’t known is why. In a paper published today in the scientific journal Nature Ecology & Evolution, researchers from the University of Minnesota and Université du Québec à Montréal show the talent behind the trait: Thanks to their natural different growth forms and ability to modify their shape to fit the available space, multiple species are able to fill in vertical gaps with branches and leaves. This maximizes their combined ability to soak up the sun falling on a particular plot of land and turn it into tree — absorbing planet-warming carbon dioxide and producing wood in the process.