Format: ORAL

Aaron Prez-Haase, Eullia Pladevall-Izard, Josep M. Ninot, Jos M. Blanco-Moreno, Vctor Lecegui-Carnero, Nil Escol-Lamora, Empar Carrillo

University of Barcelona, Barcelona, Spain

Pyrenean mountain wetlands are unique ecosystems that face several threats (overgrazing, dam regulation, drainage, tree encroachment, etc.), which keep them away from a favourable conservation status. To help tackling the main management challenges, since 2014 we have assessed (and monitored) the condition and primary threats of Pyrenean wetlands through extensive field sampling. Our findings revealed overgrazing as the predominant disturbance, affecting 24% of these wetlands. Dry spells and water table drawdown were also of primary importance and affected habitats differentially. Dam regulation and pine encroachment had intermediate importance, whereas other threats were less relevant. Consequently, we initiated pilot restoration experiments involving plant transplantations or removals to address these challenges. To mitigate overgrazing, we set up 14 exclusion fences -both permanent and temporary-, where, through passive restoration, we observed a significant recovery of plant cover, particularly on pugged soils. Plant community composition showed a slow trend from pioneer to late-successional wetland specialists. Fostering this natural process, we undertook active restoration on four wetlands by the transplantation of selected specialist species (Carex nigra, Valeriana dioica, etc.). To counteract the effects hydroelectric regulation, we performed the initiation of two wetland habitats on the shores of a decommissioned reservoir by transplanting sedges (Carex rostrata) and peat mosses (four species, including vulnerable Sphagnum magellanicum). Although restoration was successful for both habitats, dry spells affected severely sphagnum hummocks, whereas wet sphagnum carpets endured unaltered. As for encroachment, we set up a pine clearcutting action, which will expectedly lead to a rise of the water table by a reduction of tree transpiration, and to the removal of negative shadowing on wetland-specialists. The knowledge gained from the successes -and failures- of our pilot restoration experiments can be used to guide management decisions for improving the conservation status of mountain wetlands.