CONICET | Buscador de Institutos y Recursos Humanos

To succeed in habitats where ectomycorrhizal (ECM) fungi are absent, pines need to co-invade with their fungalpartners. In mountains from central Argentina there are no native ECM hosts, thus we cannot currently predict if climateand/or lack of compatible fungal symbionts constrain pine expansion from plantations toward distances and altitudes inwhich there are absent. We combined DNA meta-barcoding of soils and field experiments along an altitudinal gradientthat is subjected to an incipient spread of exotic Pinus elliottii to assess a) whether fungal partners are present in soilsat different altitudes and b) if pines can survive and form ectomycorrhizas at elevations outside of their current range.Three plots were selected at four sites along the altitudinal gradient (900, 1,600, 2,200, and 2,700 masl). They were establishedat approximately 110, 3,000, 6,000, and 9,000 m from the closest pine plantation, respectively. Eight seedlingswere transplanted to each plot soil at each altitude. Plants were harvested in two stages (before and after winter). Forsoil analyses, a pine plantation close to the lowest site was also selected. Among the 31 ectomycorrhizal OTUs foundin the pine plantation, 11 were found at other altitudes, indicating the presence of suitable fungal symbionts in the soilspore bank even at considerable distances from plantations. After five months (before winter), pine seedlings survivedat all altitudes. At least one individual from 900, 1,600, and 2,200 was colonized by Suillus granulatus. Two individuals at1,500 m asl were also colonized by Rhizopogon sp. and Thelephora terrestris. After 11 months, individuals also survivedat all altitudes but only one individual at 1,500 masl showed colonization by Suillus granulatus. Our results show thatpines can survive, find suitable fungal symbionts and form ectomycorrhizas at long distances from plantations and at elevationswhere they currently do not occur