Trees communicate via a “wood wide web” of roots and microbes in ways that enhance their growth and can reduce carbon dioxide in the atmosphere, mitigating climate change. But no one knows why so many tropical trees team up with bacteria to capture nitrogen from the air when they already grow in nitrogen-rich soils. A super-sized experiment at the Smithsonian Tropical Research Institute (STRI) to address this paradox showed that each species has its own unique nutrient-capture strategies, underscoring the importance of biodiversity for successful reforestation projects.