Tourbières observatory

Tourbières observatory

Scientific context

The Tourbières observatory is a network of 4 instrumented peatlands located along a topographic (from 100 to 1,400 m) and anthropization gradient: La Guette and Landemarais in the plains with oceanic climate, Frasne at medium altitude in Jura and Bernadouze in the Pyrénées chain.

These peatlands are wetlands characterized by a particular moss, the sphagnum moss. It thrives at high rainfall, often low temperatures, and acidic and nutrient-poor water. Sphagnum mosses are ingenious species: by their morphological and chemical characteristics, they are able to promote the favorable conditions for their own development. These conditions limit biological decomposition so efficiently that organic matter accumulates and forms peat. These original and critical ecosystems are home to a unique biodiversity and play a crucial role in the carbon cycle. Despite a cover of 3% of the land surface, peatlands contain between 25% and 30% of the world’s soil carbon stock.

Summary

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Starting year: 2008 at la Guette and Frasne, 2012 at Bernadouze, 2014 at Landemarais

Locations: Brittany, Drugeon valley, Vicdessos valley, Sologne

Keywords: wetlands, carbon footprint, climate change, greenhouse gases

Database:
https://data-snot.cnrs.fr/data-access/

Web site:
https://www.sno-tourbieres.cnrs.fr/

PIs: Sébastien Gogo
La Guette: Sébastien Gogo
Frasne: Guillaume Bertrand
Bernadouze: Laure Gandois

Station de mesure eddy covariance à la tourbière de Frasne pour le suivi sur le long terme des flux de gaz à effet de serre.
eddy covariance station at the Frasne peat bog for the long-term monitoring of greenhouse gas fluxes.
© Adrien Jacotot

Scientific questions

The scientific questions of the Tourbières observatory are:

  • What is the current carbon and hydrological balance of peatlands?
  • What is the response of peatlands to climate change in terms of both processes and greenhouse gas fluxes?

The peatlands of the network provide strong constraints to feed global climate change space-for-time substitution models. One of the 4 sites, La Guette, has been accredited since 2019 as an associated site in the European research infrastructure for observing greenhouse gas flows: ICOS-Ecosystem (Integrated Carbon Observation System).

Sites and measured variables

The sites of the Tourbières are the following ones: la Guette peatland in Sologne (145 m, 26 ha, 11 °C average annual temperature, 880 mm/year rainfall, Sologne sands), the Landemarais peatland north of Fougères (154 m, 23 ha, 11 °C, 870, Cadomian granites), the peatland of Frasne near Pontarlier (830 m, 98 ha, 7.5 °C, 1,400 mm/year rainfall, Jurassic limestones and moraines), and the peatland of Bernadouze in Ariège (1,400 m, 3.8 ha, 6 °C, 1,700 mm/year rainfall, Hercynian granites and moraines).

The Tourbières instruments (ground meteorological stations, closed chambers and eddy covariance station, piezometers, multiparameter hydrological station) collect measurements common to the 4 sites, at different frequencies, from several times per second to once every 30 minutes. This instrumentation ensemble makes it possible to quantify evapotranspiration and heat fluxes (sensible and latent) and organic carbon concentrations at the outlet. The hydrological variables (flow rates, piezometric levels, meteorological data) and environmental data enables the establishment of ecosystem-scale carbon and hydrological balances. Greenhouse measurements were implemented according to the recommendations of the ICOS RI (Integrated Carbon Observation System).

The Tourbières observatory also hosts in situ experimental devices for simulating climate and anthropogenic forcing. The Tourbières sites also host national and European ecological restoration projects (regional projects, LIFE and INTERREG programs).

Station de mesure du rayonnement global (A) et expérimentation d’augmentation de la température de l’air avec des « open top chambers » (OTC) à la tourbière de Frasne.
Global radiation measurement station (A) and experimentation of air temperature increase with “open top chambers” (OTC) at the Frasne peat bog. © Adrien Jacotot in 2019
Fluorimètre installé dans le cours d’eau à l’ éxutoire de la tourbière de la Guette pour l’estimation des concentrations en carbone organique dissous.
Fluorometer installed in the stream at the outlet of the Guette Bog for the estimation of dissolved organic carbon concentrations. © Jannin in 2016
Station eddy covariance de la tourbière de la Guette avec de droite à gauche : anémomètre à ultrasons 3D, analyseurs CO2 et CH4.
Eddy covariance station at La Guette peat bog with from right to left: 3D ultrasonic anemometer, CO2 and CH4 analyzers. © Baptiste Paroissien in 2018

Partners and further information

Tourbières is an observation service labelled by the INSU-CNRS. It is led by the Observatoire des Sciences de l’Univers en région Centre (OSUC) and the Institut des Sciences de la Terre d’Orléans (ISTO) in collaboration with the Observatoire des Sciences de l’Univers Terre-Homme Environnement-Temps-Astronomie (OSU THETA), the Laboratoire Chrono-Environnement (Besançon), the Observatoire des Sciences de l’Univers de Rennes (OSUR), l’unité ECOBIO (Rennes), the Observatoire Homme-Milieu Pyrénées (OHM Haut-Vicdessos), the Laboratoire GÉODE and the Laboratoire ECOLAB (Toulouse). All the sites are integrated in a Zone Atelier (ZA) of the INEE (IR Réseau des Zones Ateliers): Frasne in ZA Arc Jurassien, Landemarais in ZA Armorique, la Guette ZA Loire and Bernadouze in ZA PyGar.

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