Northward shifting in the distribution of optimal niches for Tuber aestivum, Tuber melanosporum, and their ectomycorrhizal tree partners in Europe

Truffles are valuable edible fungi, which form an ectomycorrhizal symbiosis with trees, thus their distribution depends on the presence of appropriate tree partners. Global warming threatens truffles and trees in the Mediterranean Basin, hence the future of truffle cultivation in this region.

We aimed to predict the potential distribution of Tuber melanosporum, T. aestivum, and their tree partners in Europe under changing climate. We compared the results obtained among widespread (Quercus robur, Corylus avellana), common in the Mediterranean region (Q.ilex, Castanea sativa), and non-native tree used in truffle orchards in the United States (Carya illinoinensis). We used distribution data from GBIF and literature. Using MaxEnt models, we prepared species distribution models related to climate change between 2020 and 2080 based on 19 bioclimatic variables, distribution data of trees, and climate change scenarios A1b, A2a, and B2b.

We predicted a northward shift in the future distribution of niches for truffles and trees, a major decrease in the area of niches for truffles in southern Europe, and a substantial increase in central and northern Europe. The general trend was common for tested species and climatic scenarios. The distribution of ectomycorrhizal trees was the predictor of highest importance for truffles. Among climatic variables, precipitation of coldest quarter, temperature seasonality, and annual mean temperature contributed the highest importance.

Because the consequences of global warming seriously threaten truffles and their tree partners in southern Europe but generate novel climatic niches for these species in regions situated further north, we suggest that cultivation of truffles should be moved northward along with patterns of climate change.