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.