The critical role of tree species and human disturbance in determining the macrofungal diversity in Europe

Aim: Knowledge concerning species distribution is important for biodiversity conservation and environmental management. Fungi form a large and diverse group of species and play a key role in nutrient cycling and carbon storage. However, our understanding of fungal diversity and distribution remains limited, particularly at large spatial scales. Here, we predicted the diversity and distribution of ectomycorrhizal and saprotrophic macrofungi at relatively fine spatial resolution at a continental scale and examined the importance of variables that affect the distribution of these two functional groups. Location: Europe. Time period: 1990–2018. Major taxa studied: Macrofungi. Methods: From observations of 1,845 macrofungal species, we predicted the diversity and distribution of two functional groups of macrofungi at a resolution of 5 km across eight European countries based on 25 environmental variables using the MaxEnt model. We determined the importance of variables that affect the distribution of these two functional groups of macrofungi using the built-in jackknife test in the model. Results: Analysis of the modelling results showed that eastern Denmark and southern Sweden are biodiversity hotspots for both functional groups of macrofungal species. Tree species and human disturbance (i.e., the human footprint index) were found to be the two most important predictor variables explaining the distribution of ectomycorrhizal and saprotrophic macrofungi. Main conclusions: Overall, our study demonstrates that tree species and human disturbance have played a more important role than climatic factors in determining the diversity and distribution of macrofungi at the continental scale. Our study suggests that fungal diversity and distribution might change considerably if the strongest predictors (i.e., tree species) were to be affected by climate change and/or human activity. Changes in fungal diversity might, in turn, influence other processes, because fungi are important in driving ecosystem processes, such as nutrient and carbon cycling.