Sporecasting Biogeography Across Scales: Continental Patterns and Local Constraints on Macrofungal Dispersal

Area of Science:

• Ecology
• Mycology
• Biogeography

Background:

• Understanding aerial fungal diversity is crucial for linking local reproduction to continental biogeography.
• Macrofungal sporocarps (fruiting bodies) are key indicators of fungal communities.

Purpose of the Study:

• To investigate how site, habitat, and fire history influence aerial macrofungal communities across North America.
• To quantify the factors shaping aerial fungal diversity and community composition.

Main Methods:

• Combined passive spore trap metabarcoding with macrofungal sporocarp records from 31 plots in eight North American sites.
• Analyzed 823 samples to identify 7572 operational taxonomic units (OTUs), with nearly half belonging to macrofungi.

Main Results:

• Macrofungal aerial DNA abundance and OTU richness increased with temperature and precipitation.
• Forest habitats showed higher aerial DNA abundance than grasslands, and conifer forests had higher OTU richness.
• Geographic distance was the primary driver of community similarity (16%), while fire history had limited impact.

Conclusions:

• Aerial macrofungal assemblages exhibit continental structure but remain locally heterogeneous.
• Environmental filtering, functional guild associations, and limited dispersal are key shaping factors.
• Integration with sporocarp records suggests a ~3 km effective spore trap input range, indicating dispersal limitation.