Fungal fruit body assemblages are tougher in harsh microclimates

Forest species are affected by macroclimate, however, the microclimatic variability can be more extreme and change through climate change. Fungal fruiting community composition was affected by microclimatic differences. Here we ask whether differences in the fruiting community can be explained by morphological traits of the fruit body, which may help endure harsh conditions. We used a dead wood experiment and macrofungal fruit body size, color, and toughness. We exposed logs of two host tree species under closed and experimentally opened forest canopies in a random-block design for four years and identified all visible fruit bodies of two fungal lineages (Basidio- and Ascomycota). We found a consistently higher proportion of tough-fleshed species in harsher microclimates under open canopies. Although significant, responses of community fruit body size and color lightness were inconsistent across lineages. We suggest the toughness-protection hypothesis, stating that tough-fleshed fruit bodies protect from microclimatic extremes by reducing dehydration. Our study suggests that the predicted increase of microclimatic harshness with climate change will likely decrease the presence of soft-fleshed fruit bodies. Whether harsh microclimates also affect the mycelium of macrofungi with different fruit body morphology would complement our findings and increase predictability under climate change.

Automated summary

Forest species can be affected by both macroclimate and microclimatic variability. In this study, we found that the fruiting community of fungi was influenced by microclimatic differences. We also discovered that tough-fleshed species were more common in harsher microclimates under open canopies. However, the responses of fruit body size and color were inconsistent across different fungal lineages. Our findings suggest that tough-fleshed fruit bodies may provide protection against microclimatic extremes by reducing dehydration. As climate change leads to increased microclimatic harshness, the presence of soft-fleshed fruit bodies is likely to decrease.