I am interested in ecosystem biogeochemistry, soil-plant-atmosphere interactions, and global change ecology. My research focuses on the impacts of climate change and human activities on ecosystem processes and functions, and the feedback to the climate and Earth system. I use observational, experimental, and modeling approaches to understand and simulate carbon, nitrogen, and water cycles within ecosystems and between the Earth surface and the atmosphere across various scales. My research improves our understanding of ecosystem services and informs sound environmental and climate policies. I study ecosystems that range from semiarid forests and savanna grassland in the Sierra Nevada of California, northern forests and prairie grassland in the Midwestern U.S., temperate forests and coastal wetlands in New England, and tundra ecosystems in the Arctic. Currently, I focus on three major topics under a unified theme of ecosystem ecology and biogeochemistry.