Environmental drivers shaping the macrofungal sporocarp community in Mediterranean Quercus ilex stands

Abstract

Holm oak is one of the most abundant tree-forming species in the Mediterranean area, hosting a great number of fungal species that are fundamental for the functioning of these forest ecosystems. However, the information about the fungal communities growing in Quercus ilex stands and the environmental drivers shaping their fruiting patterns is still scarce. This study aimed to characterize the productivity, diversity, and community composition of macrofungal sporocarps growing in Mediterranean Quercus ilex stands as shaped by key environmental drivers including meteorological and soil variables. We analysed a data set obtained from the autumn weekly sampling of all macrofungal sporocarps from 8 permanent plots over 13 consecutive years, and related weather and soil variables. We built up several linear mixed-effects models to describe productivity and richness changes over time, in addition to multivariate analyses aiming to describe the community composition variations. We identified 241 macrofungal species that were predominantly ectomycorrhizal, with Russulaceae and Cortinariaceae being the most abundant families. Agaricaceae and Tricholomataceae were the most abundant families of saprotrophic fungi. In addition, soil properties such as pH, organic matter and sand content played a significant role in sporocarp community composition. Our results highlight different drivers shaping different fungal fruiting processes, i.e., weather variables drive sporocarp productivity and sporocarp richness while soil characteristics may have a stronger influence on the aboveground fungal community composition. This study illustrates the high stochasticity of sporocarp occurrence and productivity, with species exhibiting higher values whenever the meteorological conditions were suitable for fungal fruiting.