Restoring High Mountain Sphagnum Communities in Central Pyrenees

A handful of Sphagnum species and their ecosystems have in the Pyrenees their south-ernmost occurrence. These small, relict units are endangered through anthropic activities and by climatic change. A number of hydropower reservoirs had covered by water, or let ashore, former mire systems. These infrastructures will eventually become useless and abandoned, and the possibility of restoring mires is realistic –while no experiences in this field are known in the Pyrenees. The removal of the dam of a small reservoir at the Central Pyrenees in 2012 uncovered bare ground appropriate to test the restoration of mires. In 2017, we started the restoration of two Habitats of Community Interest (HCI), i.e., the transition mire of Carex rostrata and Sphagnum (HCI 7140) and the Sphagnum bogs (HCI 7110*). To restore HCI 7140, we set a C. rostrata population by planting cuttings, and then small tufts of two Sphagnum species within the sedge sward. In parallel, we set small clumps of other two Sphagnum species intended to grow into hummocks (HCI 7110*). After seven growing seasons, HCI 7140 reached a good evolution level, with a prosperous C. rostrata sward and progressive expansion of the Sphagnum populations. HCI 7110* turfs performed variously, exhibiting moderate survivorship and positive expansion of the remaining turfs. The varying performance of the species restored gives evaluation of the possibilities of restoring mire communities in suboptimal environments. Interestingly, such restoration actions are appropriate to enhance populations of species under threat, as is Sphagnum divinum.