A new, isolated and endangered relict population of dwarf pine (Pinus mugo Turra) in the northwestern Alps.

Dwarf pines were discovered in 2004 during a paleoecological survey in the Mont Cenis massif (Savoy, France). These dwarf pines are the sole natural and spontaneous population in the NW French Alps of Pinus mugo Turra, ssp. mughus (Scop.) O. Schwarz. The population, fragile in light of the individual numbers, is currently isolated, but likely results from populations that would have covered larger areas during the Lateglacial or the early-Holocene, from the SW Alps (France) toward the Mont Cenis, throughout the Susa valley (Italy). With a fragmented distribution area of dwarf pine, the future of the Mont Cenis population seems altered due to important necroses observed on the topmost part of pine crowns, except for individuals that do not grow in the local ski station area. We stress the need for a conservation program to preserve this natural population, the sole known in the NW French Alps.