The need to develop and provide integrated observation systems to better understand and manage global and regional environmental change is one of the major challenges facing Earth system science today. In 2008, the German Helmholtz Association took up this challenge and launched the German research infrastructure TERrestrial ENvironmental Observatories (TERENO). The aim of TERENO is the establishment and maintenance of a network of observatories as a basis for an interdisciplinary and long-term research programme to investigate the effects of global environmental change on terrestrial ecosystems and their socio-economic consequences. State-of-the-art methods from the field of environmental monitoring, geophysics, remote sensing, and modelling are used to record and analyze states and fluxes in different environmental disciplines from groundwater through the vadose zone, surface water, and biosphere, up to the lower atmosphere. Over the past 15 years we have collectively gained experience in operating a long-term observing network, thereby overcoming unexpected operational and institutional challenges, exceeding expectations, and facilitating new research. Today, the TERENO network is a key pillar for environmental modelling and forecasting in Germany, an information hub for practitioners and policy stakeholders in agriculture, forestry, and water management at regional to national levels, a nucleus for international collaboration, academic training and scientific outreach, an important anchor for large-scale experiments, and a trigger for methodological innovation and technological progress. This article describes TERENO’s key services and functions, presents the main lessons learned from this 15-year effort, and emphasises the need to continue long-term integrated environmental monitoring programmes in the future.

Climatic warming is predicted to affect high-latitude habitats, such as boreal peatlands, at a larger magnitude than the global average. The controls on the breakdown of organic matter in peatlands are complex; it’s unclear how climatic warming will affect the stability of the large carbon pool that’s currently stored in peatlands. To investigate this, we collected soil cores from three boreal habitats along a hydrological transect (Bog, Intermediate, and Upland Forest) in Finland, and incubated ex-situ for 140 days. Each soil horizon was incubated in three temperatures (0°C, 4°C, 20°C). Here, we found the Intermediate site had the largest CO2 production considering the entirety of the soil column (per gram dry weight). Statistical analysis found that sample C content was the most indicative independent variable to predict sample CO2 production. Each soil horizon displayed a different magnitude of response to the temperature incubations (Q10s ranged from 0.60-2.33), and through microbial relative abundance analysis we found that the microbial community structure had significant differences between both habitat and depth of sample origin. Coupling these methods, and the fine scale of the both vertical (soil column horizons) and horizontal (along a hydrological gradient through distinct habitats) transects gives us a novel perspective on the controls of microbial respiration rates. Our results stress that large scale modeling efforts of carbon dynamics should prioritize both soil carbon quantity and quality.