Most works on land system changes take either a quantitative approach on land cover and use or a qualitative approach on land function. The aim of this research is to study urban green in European medium-sized urban areas (MSUA) with an interdisciplinary approach using mixed methods. In the course of this research, the case studies are gradually being reduced: from a study of land cover and land use changes related to urban green in 214 European MSUA to an analysis of urban green functions in 4 shrinking cities: Salamanca, Metz, Magdeburg and Szczecin. This innovative approach based on various types of data (CLC, LUCAS, strategic planning documents and interviews) leads to several conclusions on the way urban green is changing in European MSUA along the three components of the land system: cover, use and function. Additionally, it gives a reflection on methodological problems when considering land system changes with a comparative approach at the European regional scale.