Suchergebnisse

Soil microclimate is a potentially important regulator of the composition of plant‐associated fungal communities in climates with significant drought periods. Here, we investigated the spatio‐temporal dynamics of soil fungal communities in a Mediterranean Pinus pinaster forest in relation to soil moisture and temperature. Fungal communities in 336 soil samples collected monthly over 1 year from 28 long‐term experimental plots were assessed by PacBio sequencing of ITS2 amplicons. Total fungal biomass was estimated by analysing ergosterol. Community changes were analysed in the context of functional traits. Soil fungal biomass was lowest during summer and late winter and highest during autumn, concurrent with a greater relative abundance of mycorrhizal species. Intra‐annual spatio‐temporal changes in community composition correlated significantly with soil moisture and temperature. Mycorrhizal fungi were less affected by summer drought than free‐living fungi. In particular, mycorrhizal species of the short‐distance exploration type increased in relative abundance under dry conditions, whereas species of the long‐distance exploration type were more abundant under wetter conditions. Our observations demonstrate a potential for compositional and functional shifts in fungal communities in response to changing climatic conditions. Free‐living fungi and mycorrhizal species with extensive mycelia may be negatively affected by increasing drought periods in Mediterranean forest ecosystems. ; This work was supported by the Spanish Ministry of Economy and Competitivity (MINECO) (grant number AGL2015‐66001‐C3). C.C. received support from the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya through the program of Doctorats Industrials, funded by the European Union and the European Social Fund. J.G.A. was supported by Juan de la Cierva (Grant number IJCI‐2014‐21393) and Ramon y Cajal fellowships (RYC‐2016‐20528) and J.A.B. benefits from the Serra‐Hunter Fellowship.

Predicted changes in global climate might negatively affect the soil microbiome and associated ecosystem processes in Mediterranean forests. Forest treatments, such as forest thinning, have been suggested to mitigate climate change impacts on vegetation by reducing competition between trees, thus increasing water availability. Studies addressing the combined effects of climate and forest thinning on belowground fungal communities are still scarce, being fundamental to elaborate adaptive strategies to global warming. The aim of this study was to evaluate the tree density reduction effects on soil fungal communities and their response to inter-annual changes in weather conditions. The temporal dynamics of soil fungal communities in relation to these two drivers (i.e., forest management and weather conditions) were studied from 2009 until 2014 in a set of 12 pairs of thinned and un-thinned plots dominated by Pinus pinaster Ait. Thinning (from 30% up to 70% reduction in stand basal area) was conducted in 2009 and soil fungal community composition was studied during 4 years. Here, we used autumn precipitation and temperature to describe the impact of inter-annual weather changes. We used Pacific Biosciences sequencing of fungal ITS2 amplicons to study fungal communities in soil samples. Forest thinning did not significantly affect fungal community composition nor fungal species richness and diversity, indicating that the soil fungal community is resistant to forest thinning regardless of its intensity. However, fungal species composition changed progressively across years, both at the species level and with regards to functional guilds. These changes in community composition were partly driven by inter-annual variation in precipitation and temperature, with free-living fungi increasing in abundance under wetter conditions, and symbiotic fungi being more prominent under drier and colder conditions. The results indicate that mycorrhizal communities in Mediterranean forest ecosystems can resist forest thinning, if enough trees and functional roots from thinned trees are retained. ; This work was supported by the Spanish Ministry of Economy and Competitivity (MINECO) [grant number AGL2015-66001-C3] and by the Collaborative European project ERANET-INFORMED (PCIN-2014-050). Carles Castaño received the support of the Doctorats Industrials program, funded by the European Union and the European Social Fund. Sergio de-Miguel was supported by the European Union's Horizon 2020 MultiFUNGtionality Marie Skłodowska-Curie [Grant number IF-EF No-655815]. Josu G. Alday was supported by Ramon y Cajal fellowship [Grant number RYC-2016-20528] and José Antonio Bonet benefited from a Serra-Húnter Fellowship provided by the Generalitat of Catalunya. The authors are very grateful to the PNIN of Poblet for its considerable help with the process of installing and maintaining the experimental plots. We thank Liu Bing, Daniel Oliach, Francesc Bolaño, Jordi Margalef, Josep Miró and Jewel Yurkewich for their assistance with sampling the plots and processing the samples. The constructive comments and suggestions of two anonymous reviewers were improved substantially this manuscript.