The Integrated European Long-Term Ecosystem, critical zone and socio-ecological system Research Infrastructure (eLTER RI) is a distributed RI to facilitate high impact research and catalyse new insights about the compounded impacts of climate change, biodiversity loss, soil degradation, pollution, and unsustainable resource use on a range of European socio-ecological systems. eLTER RI aspires to develop the scientific capacity to improve the understanding of terrestrial, freshwater, and transitional water ecosystems. Combined with socio-ecological approach to studying integrated human-nature systems and commitment to integrating stakeholder knowledge, it provides a solid foundation to inform policy-maker systems to find evidencebased sustainable solutions for addressing current and emerging challenges.

eLTER has evolved via several flagship networks and projects – e.g. ALTER-Net, EnvEurope, ExpeER and eLTER H2020. Cited as emerging project in 2016, it was successfully selected and included in the ESFRI Roadmap 2018. eLTER is currently in the Preparation Phase on the way to become a fully-fledged RI that will comprise National Research Infrastructures (NRIs), and European level Central Services (CS), such as data access, training and harmonized methods and parameters. Countries supporting eLTER RI will provide facilities in the form of eLTER Sites (focal points for long-term ecosystem observation and research) and eLTSER Platforms (large areas facilitating socioecological research and exemplary stakeholder engagement). These national building blocks shape the in situ backbone of eLTER RI.