Evolution of scientific questions over 50 years in the Kervidy-Naizin catchment: from catchment hydrology to integrated studies of biogeochemical cycles and agroecosystems in a rural landscape

Catchment studies on water quality started in the 1960s, when scientists identified long-term environmental impacts and realized the complexity involved in environmental degradation and recovery. Since scientists need to understand biogeochemical and hydrological processes in detail, long-term observatories have been established over time, particularly in the field of catchment hydrology and biochemistry. The AgrHyS (for “AgroHydroSystem”) observatory comprises two small catchments in Brittany (France) and this article unfolds the evolution over 50 years of the scientific questions and related observations and studies in one of them, the Kervidy-Naizin catchment. While a well-defined set of variables was monitored since the beginning (the “basic observatory basket”), the research topics and additional monitored variables were much broader. The first 25 years focused on hydrological and biogeochemical processes, while the next 25 years focused on more integrated issues related to soil ecology and landscape biogeochemical cycles. The AgrHyS observatory has succeeded in fostering interdisciplinary research. The current challenge is the engagement of the observatory in international networks to enable inter-comparison of hydro-systems response to gradients of different land use and environmental conditions.