How OZCAR, TERENO and eLTER Shape the Future of Environmental Observation

The 3^rd OZCAR TERENO conference was the third edition of a conference cycle organised every two years in France and Germany by the French Critical Zone Observatory network (OZCAR) and the German TERENO network (Terrestrial Environmental Observatories). Held in Paris, France, on 29 Sept – 2 October 2025, the event brought together around 270 participants who enjoyed an intensive scientific program. Highlights included a field trip, keynote presentations, and scientific sessions that provided novel insights into Critical Zone research. About 40% of the participants were Early Career Researchers, reflecting a strong potential for renewal and a fresh, future-oriented approach in the field. 

By bringing together a variety of disciplines, including hydrology, geophysics, soil sciences, geochemistry, ecology, and socio-ecology, the conference highlighted interdisciplinary research that addressed the functioning of the Critical Zone in the Anthropocene. The meeting also demonstrated how the use of multidisciplinary Critical Zone observatories, highly instrumented field sites where these disciplines interact and produce data and models, provide new insight for an integrated understanding of the the outermost layer of the planet where all human activities concentrate.

Both OZCAR and TERENO are foundational networks of the emerging eLTER Research Infrastructure and contribute to shaping the eLTER RI. eLTER’s co-coordinator Jaana Bäck (University of Helsinki) therefore gave a keynote showcasing eLTER’s progress towards the operational RI, including a presentation of eLTER’s emerging Topic Centres and Site Categories.

In addition, a session on ‘Long-term environmental observation for understanding the Earth system in the Anthropocene’ organised by Steffen Zacharias (UFZ, Leipzig), Thomas Pütz (FZ Jülich), and Jérôme Gaillardet (IPGP, Paris) discussed long-term observations across geo-, hydro-, atmospheric and socio-ecological spheres, comparing approaches for integrative ecosystem monitoring and addressing the challenge of upscaling local insights to continental scales.

Thomas Ohnemus (UFZ, Leipzig) with his presentation on ‘The Potential of Colocation to mitigate Sampling Bias in Research Infrastructures’, during ‘Long-term environmental observation for understanding the Earth system in the Anthropocene’ session

Meetings like the biannual OZCAR TERENO conference provide an essential forum for scientists to exchange knowledge, align methodologies, and explore synergies across disciplines and networks. These dialogues not only strengthen collaboration between existing observatory communities, but also accelerate the development of eLTER RI as a truly integrative European Research Infrastructure. 

For national research infrastructures such as OZCAR and TERENO, participation in eLTER offers the added value of shared standards, interoperable methods, and a stronger collective voice, elevating their impact while preserving their unique strengths. By drawing on the best methods and insights from its partner research communities, eLTER is positioning itself to deliver cutting-edge capacities for long-term ecosystem and socio-ecological observation in the Anthropocene.