Differential hypogeous sporocarp production from Nothofagus dombeyi and N. pumilio forests in southern Argentina

Abstract

Mycorrhizal fungi that form hypogeous sporocarps are an important component of the temperate forest soil community. In many regions, such as the Nothofagus forest in the Patagonian Andes, this group of fungi has been poorly studied. Here we examined the spring and autumn community composition of "sequestrate fungi", based on sporocarp production in pure forests of Nothofagus dombeyi (evergreen) and N. pumilio (deciduous). We investigated the possible relationships between these communities and environmental factors over 2 y. The rarefaction curves and the minimal richness estimates converged at nearly the same level for each forest type, and the asymptotes suggested that the sampling effort was sufficient to capture most of the hypogeous sporocarp richness in these forest stands. In total 27 species were recovered. Basidiomycota, Ascomycota and Glomeromycota respectively accounted for nine, two and one genera. Species richness of hypogeous sporocarps varied in relation to forest type but not to season (fall and spring), whereas sporocarp biomass varied according to an interaction between season and forest type. Species richness and sporocarp biomass were positively correlated with rainfall and negatively correlated with altitude. In addition sporocarp species richness was positively related to number of trees per transect. We found that two different forest stands, each dominated by different species of Nothofagus, exhibited different hypogeous sporocarp communities.

Ectomycorrhizal fungal communities in Nothofagus nervosa ( Raulí ): A comparison between domesticated and naturally established specimens in a native forest of Patagonia, Argentina

“…A total of 25 fungal species were identified, most (88%) belonging to the Basidiomycota. This result is in agreement with previous studies in Nothofagus (Tedersoo et al, 2009;Nouhra et al, 2013) and other important forestry species. The Cortinariaceae and Tricholomataceae were the only families represented by more than two species (Table 1).…”

“…These taxa were described as abundant in Nothofagus roots (Tedersoo et al, 2009;Nouhra et al, 2013). Our results were in accordance with Nouhra et al (2013), who stated that there is a high level of similarity in the EcMF communities associated with different Nothofagus species.…”

“…The sequences obtained were compared with those available in the NCBI GenBank database (http://www.ncbi.nlm.nih.gov) using the BLASTn algorithm. Sequences were assigned to species based on !97% ITS sequence similarity threshold (Nouhra et al, 2013). The PubMed database (http://www.ncbi.nlm.nih.gov/ Taxonomy/Browser/wwwtax.cgi) was used for nomenclature and classification of the species.…”

“…The main limitation of this type of soil is high P retention (Mazzarino and Gobbi, 2005). The fact that Nothofagus roots are extensively colonized by EcM (Tedersoo et al, 2009;Nouhra et al, 2013) with rates usually higher than 70% (Diehl et al, 2008;Longo et al, 2011;Fern andez et al, 2013), and that these tree species are not proficient at P uptake, suggest a strong dependence on this symbiosis, and that EcM constitute an effective adaptation mechanism to soils with low P availability (Mazzarino and Gobbi, 2005;Diehl et al, 2008).…”

“…Therefore, the mycorrhizas associated with N. nervosa are one of the factors that should be considered during domestication programs. However, there is little information concerning the composition or community dynamics of the ectomycorrhizal fungi (EcMF) colonizing Nothofagus roots in South American natural environments (Nouhra et al, 2013), and the influence of age, seasonality and/ or domestication practices on mycorrhizal fungal communities is not known. The main objective of this study was to compare the abundance and diversity of EcM associated with domesticated N. nervosa specimens outplanted in a native forest with naturally established trees, and to analyse the influence of various factors (age, seasonality, domestication practices) on this symbiosis.…”