What happens to the mycorrhizal communities of native and exotic seedlings when Pseudotsuga menziesii invades Nothofagaceae forests in Patagonia, Argentina?

SALGADO SALOMÓN, MARÍA EUGENIA; BARROETAVEÑA, CAROLINA; PILDAIN, MARÍA BELÉN; WILLIAMS, EMILIO ADOLFO; RAJCHENBERG, MARIO

ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY

GAUTHIER-VILLARS/EDITIONS ELSEVIER

Año: 2018 vol. 91 p. 108 - 119

1146-609X

Pseudotsuga menziesii is one of the most widely planted conifers in the Patagonian Andes of Argentina, havinginvading characteristics that are broadly reported. We studied the mycorrhizal status of seedlings along sixNothofagaceae + P. menziesii invasion matrices to investigate their role in the invasive process, according tothese hypothesis: a) The abundance and richness of EM will be higher in seedlings grown in their own soil; b) Inthe presence of native EM inoculum, the invasive plant will be associated with generalist mycorrhizae (EM and/or AM), c) AM associations will be more abundant in P. menziesii seedlings grown in Interface or native forestsoils, d) Mycorrhizal community differences between treatments will alter host fitness (growth and nutritionalparameters). Seedlings from Nothofagus dombeyi, N. antarctica, Lophozonia alpina, L. obliqua and Pseudotsugamenziesii were set up in a soil-bioassay that included soils from non-invaded Nothofagaceae forests, pure P.menziesii plantations, and the interface between both. Pseudotsuga menziesii seedlings showed a decreasing, although never null, ectomycorrhizal (EM) colonization pattern from plantations to non-invaded forests, mainlywith exotic EM species. Hebeloma mesophaeum and Wilcoxina sp. 1, two EM species with cosmopolitan distribution, were found to be shared by both tree species. Hebeloma hiemale and Wilcoxina sp. 1, common mycorrhizal partners of P. menziesii in Patagonia although not registered from Nothofagaceae forest, were found tobe associated with N. antarctica, being the first report for both fungal species. Pseudotsuga menziesii seedlingsshowed the ability to form different arbuscular mycorrhiza (AM) colonization types (Paris-, Arum-, Both- andIntermediate-types) depending on the treatments, with significantly higher presence of Intermediate-type in theInterface treatment, where colonization was low. The shared EM species and the presence of different AM colonization types imply enhanced possibilities for invasive P. menziesii seedlings establishment and development.Seedling features and EM colonization rates evidenced that P. menziesii invasion could produce maladaptation(defined as a relative decline in host fitness due to altered mycorrhizal communities from native settings) ofmycorrhizal communities, seriously injuring native ecosystem.