Climate change is altering the elevation range limits of many organisms, often driving upward range shifts. In this context, reduced air pressure poses a potentially novel environmental problem for upwards migrating organisms to solve if they are to persist at high elevation as climate change continues. The goal of the project is threefold: 1) to understand how upwards migrating soil microorganisms and plant species react to lower air pressure; 2) to assess how upwards migrating soil microorganisms and plants perform with resident plants and soil microorganisms that have persisted in place under lower pressure; 3) to evaluate the effect of lower air pressure on the ecosystem water balance. The project integrates a unique extreme environment simulator (terraXcube) to simulate different alpine climate conditions, pot and mesocosm (lysimeter) experiments to disentangle the effects, and field observations from the LTSER site in Matsch/Mazia to validate the reliability of the obtained results.