Context
• Management: Association of Aquatic Zones of the Upper-Doubs.
• Description of the site: bog of 26 ha, occupied by an ac- tive raised bog (7110*), a transition mire (7140) and bog woodland with mountain pine and spruce (91DO).
• Heritage value: bog included in a natural regional reserve approved because of its wealth of flora and wildlife. Worth mentioning is the presence of: Drosera rotundifolia, Scheuchzeria palustris, Carex limosa, Andromeda polifolia, Aeshna subarctica, Colias palaeno, etc.
Verdict
A drainage network that modifies the surface flows across the bog takes the water to a karstic sink instead of the active bog (7110*). This drainage network gener- ates the topographical sinking of the peat which has reinforced this channeling of the flow of the surface water towards the sink. So, it has lost 8 ha of watershed slope going towards the active raised bog that fed it.
127
07 PROGRAM LIFE+ “BOGS OF THE JURA”: 60 BOGS TO RESTORE IN SIX YEARS
Objectives
Reestablish the surface circulation of the waters and limit the drying of the bog by neutralizing the drainage network and re-establishing a topography that allows the waters to once again be returned to the active bog.
Problems pending solution
• Progressive desiccation of the bog with advance of mountain pine and spruce towards the centre;
• Lowering and greater fluctuation of the phreatic level.
Cost
€ 212,125 taxes not included, + € 28,000 taxes not included, for the felling of the trees and financial compensation. Assembly and moni- toring of the project not included.
Monitoring-evaluation • Piezometry.
• Hydrometry and hydrochemistry at the exit of the bog.
• Vegetation: 10 plots for monitoring (before and after the works). As the site has a significant depth
of peat, it was possible to construct enough obstacles, via dams of wooden boards and wooden panels anchored to the peat substrate, in the drainage network. In the zones where the gradi- ent was over 1.5 %, the channel was neutralized completely by filling it with peat, and blocking it with wooden pan- els. When the substrate was mineral (clay, marl, moraine), the material used for the work should not go through, or into, this hermetic layer as it can create underlying leaks. Similarly, in a sector where this layer was very fine, the choice was to preferably install a metallic stockade. The work was organ- ized as below:
• Total filling of 570 m of drainage channels with peat extracted in situ, with the addition of 10 wooden
panels and 4 dams made of wooden boards.
• Partial neutralization of 250 m of channel by creating 11 dams of wooden boards covered with peat extracted in situ.
• Construction of a metal dam 90 m covered with peat, with the aim of neutralizing the topographical sinking of the peat.
• Creation of pools to collect the peat used to fill the drain and to cover the works.
• Reopening (felling of woody plants) so as to allow access to the works and compensation paid to the owners of the trees for the loss of income. Work carried out between July and September 2015 and from May to June 2016.
INVENTORY, VALUE AND RESTORATION OF PEATLANDS AND MIRES: RECENT CONTRIBUTIONS
129
07 PROGRAM LIFE+ “BOGS OF THE JURA”: 60 BOGS TO RESTORE IN SIX YEARS
First results
Although the works are still recent, it seems that the metal dam installed in 2015 is carrying out its role and is waterlogging the system up to the desired level. The Sphagnum mosses are developing in the group of areas worked in 2015, with very favourable rainfall in spring of 2016. However, it is necessary to wait for a dry period to see how effective the works are.
Here you can see a short video explaining the works:
http://www.life-tourbieres-jura.fr/images-travaux-page.html Figure 20. Aerial view of the dams. Figure 22. Dam with peat cover. Figure 21. Dam. Figure 23. Blocking dam using a metal wall.
INVENTORY, VALUE AND RESTORATION OF PEATLANDS AND MIRES: RECENT CONTRIBUTIONS
130
Conclusion
Over several years the managers of the bogs in the Jura Franco-Comté massif have become aware of their role in the region for the preservation of bogs at national scale. In this respect, several European programs have been linked together and numerous restoration actions have been undertaken, often with technical and sci- entific support from Swiss collaborators. The LIFE+ Bogs of the Jura reflects the materialization of these dynamics. Taking advantage of the experience acquired by the whole set of agencies involved, the hydraulic functioning in the restoration has been emphasised and its fundamental importance in these zones has gradually been recognized.
At times, the Jura bogs have undergone significant modifications during their re- habilitation. However, the objective of the program was to recover the functioning of the ecosystem at the limit of the technical and ecological possibilities that each site offered. Hence, different techniques were implemented according to each habitat and the problems encountered. Some had been used successfully for several years in the Franco-Comté sites (eg: wooden dams covered with peat), and others were used for the first time in France thanks to this program: metallic dams, jointing of wooden panels. Naturally, the impact of these works will be analyzed over the period of the program thanks to a certain amount of monitoring: piezometry, water quality, fauna, flora, etc. However, in spite of the relatively long duration of the program, the evolution of the later works in the habitats and their state of conservation will be limited at the end of a six year period. There will be a wait of several years, even decades before the “definitive” results of the works in the program can be observed, especially regarding the restart of the peat making processes.
All the knowledge acquired, techniques used and the results have been com- piled and analyzed in a record of experiences up to the end of the program. This compilation will allow the transfer of good practices and increase, after a period of time, the efficiency of the management in other zones with bogs that have the same problems, at regional, national and even European level.
Lastly, awareness and communication actions have been developed over the six years of the implementation, since the involvement of the public and local agencies is essential for the long-term preservation of the bogs. In this respect, a 24 minute video has been filmed, completed with seven extra themes, and in addition there is an exhibition, made up of 11 panels, several reports about the project and numer- ous animations.
Further information at the Internet website: www.life-tourbieres-jura.fr
INVENTORY, VALUE AND RESTORATION OF PEATLANDS AND MIRES: RECENT CONTRIBUTIONS