Human activities are altering a range of environmental conditions, including atmospheric CO2 concentration, temperature, precipitation and nutrient availability. Quantifying and predicting the combined effect of these changes on biogeochemical fluxes is challenging because carbon, nutrient, and water cycles are intricately linked in terrestrial ecosystems. Descriptions of ecophysiological, biogeochemical, and hydrological processes in terrestrial ecosystem models are continually being improved, providing new insights to the feedbacks between land and atmospheric fluxes and thereby to our climate projections. However, experimental observations are required to test these new models. These data originate from observational studies as well as ecosystem manipulation studies in which environmental conditions are altered, e.g. Free-Air Carbon Dioxide Enrichment (FACE), nutrient addition, and warming experiments. This session focuses on efforts to improve our understanding of how ecosystem processes respond to changes in CO2 concentration, temperature, and nutrient availability. Contributions include both experimental and observational studies, as well as modelling exercises spanning a range of scales and conditions: soil microbial activity, plant ecophysiology, nutrient cycling, and ecosystem level dynamics.