Variable retention harvesting influences belowground plant-fungal interactions of Nothofagus pumilio seedlings in forests of southern Patagonia

HEWITT, REBECCA E.; TAYLOR, DONALD LEE; HOLLINGSWORTH, TERESA N.; ANDERSON, CHRISTOPHER B.; MARTÍNEZ PASTUR, GUILLERMO

PeerJ

Creativr Commons

Lugar: New York; Año: 2018 vol. 6 p. 1 - 16

Background. The post-harvest recovery and sustained productivity of Nothofaguspumilio forests in Tierra del Fuego may be affected by the abundance and compositionof ectomycorrhizal fungi (EMF). Timber harvesting alters EMF community structurein many managed forests, but the impacts of harvesting can vary with the managementstrategy. The implementation of variable retention (VR) management can maintain,increase, or decrease the diversity of many species, but the effects of VR on EMF in theforests of southern Patagonia have not been studied, nor has the role of EMF in theregeneration process of these forests.Methods. We evaluated the effects of VR management on the EMF communityassociated with N. pumilio seedlings. We quantified the abundance, composition, anddiversity of EMF across aggregate (AR) and dispersed (DR) retention sites within VRmanaged areas, and compared them to primary forest (PF) unmanaged stands. EMFassemblage and taxonomic identities were determined by ITS-rDNA sequencing ofindividual root tips sampled from 280 seedlings across three landscape replicates. Tobetter understand seedling performance, we tested the relationships between EMFcolonization, EMF taxonomic composition, seedling biomass, and VR treatment.Results. The majority of EMF taxa were Basidiomycota belonging to the familiesCortinariaceae (n D 29), Inocybaceae (n D 16), and Thelephoraceae (n D 8), whichwas in agreement with other studies of EMF diversity in Nothofagus forests. EMFrichness and colonization was reduced in DR compared to AR and PF. Furthermore,EMF community composition was similar between AR and PF, but differed fromthe composition in DR. EMF community composition was correlated with seedlingbiomass and soil moisture. The presence of Peziza depressa was associated withhigher seedling biomass and greater soil moisture, while Inocybe fibrillosibrunnea andCortinarius amoenus were associated with reduced seedling biomass and lower soil moisture. Seedling biomass was more strongly related to retention type than EMFcolonization, richness, or composition.Discussion. Our results demonstrate reduced EMF attributes and altered compositionin VR treatments relative to PF stands, with stronger impacts in DR compared toAR. This suggests that VR has the potential to improve the conservation status ofmanaged stands by supporting native EMF in AR. Our results also demonstrate thecomplex linkages between retention treatments, fungal community composition, andtree growth at individual and stand scales.