My research focuses on understanding and stewarding nature—as that is among our most important collective challenges in the 21st century. How rapidly and where will climate change wreak havoc with our natural and managed ecosystems? How many tree species will go extinct in the next 50 years and why does it matter? Will ecosystems continue to sequester additional carbon and thus help to slow climate change? Can traits simplify the complexity of ecology enough that we can make predictable sense of it? Raising such questions is easier than answering them. To help address them I engage in small-group to large-team studies at scales from leaf to globe and on topics from biodiversity to biogeochemistry to climate change-social justice interactions. This work ranges from ecosystem-scale field experiments with factors such as CO2, temperature, rainfall, fire and biodiversity; to cross-continental observations and earth system modeling. Our work focuses on forests and grasslands of the temperate and boreal biomes, but also includes research in many other ecosystem types and regions.