C-InterMont

High-mountains are the “water towers” of the world, supplying a substantial part of water demands for downstream ecosystems and society. Climate Change is hitting them more severely than the world on average leading to most dramatic hydrological alterations.

The expectable higher frequency of extreme climatic events will lead to a higher hydrological intermittency, in the sense of a change to a regime characterized by an alternance of extreme situations (droughts-floods). Yet biogeochemistry and ecosystem science have failed to appreciate the role of their headwaters as regulators of carbon transfers from land to the atmosphere and sea. This limitation hinders a deep understanding of how they function and thus our ability to anticipate how a more intermittent future will modify their roles in the broader C cycle.

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This project's primary goal is to develop a new framework (integrating terrestrial and aquatic as well as gradual and intermittent transitions) for understanding C transport dynamics in high-mountain headwaters and, in doing so, generate new insights on their significance to the broader landscape and regional C cycle. To achieve this, we will set-up a next-generation network of monitoring stations equipped with multiple-parametric sensors to simultaneously gather land and stream hydrologic and biogeochemical data in five plots with contrasted features in the Aigüestortes i Estany de Sant Maurici National Park. Obtained data will be used to estimate patterns of the land to stream C pool composition, flux, and metabolism over an entire seasonal cycle (and the diversity of intermittent transitions. Applying cutting-edge wavelet technics on the obtained land-stream time series, we will additionally assess the functional dependency and reliance of stream C metabolism on terrestrial ecosystem processes. Finally, the project will also use the “C spiraling” framework to answer whether or not high-mountain headwaters are “active” or “passive” landscape actors (or reactors) with respect to the C cycle. Altogether, we will be in a unique position to identify how the efficiency of C processing is influenced by different degrees of intermittency. Establishing this link is fundamental to pinpoint the future role of high-mountain headwaters in the global carbon cycle.