I use a combination of measurements and process-based models to understand processes across spatial and temporal scales, testing ecological theory, and disentangling complex ecological interactions. Ecosystem models are especially important for understanding the impacts of changes, such as climate, air pollution, and management decisions, which helps to identify possible outcomes of climate change projections and to devise potential mitigation options. Observations are necessary to understand the mechanisms driving ecosystem processes and their responses to change. Integrating these techniques affords a powerful approach to document, understand, and predict ecosystem changes across spatial and temporal scales.